Donor-Specific Antibodies Are Produced Locally in Ectopic Lymphoid Structures in Cardiac Allografts

Cardiac allograft vasculopathy (CAV) is a transplant pathology, limiting graft survival after heart transplantation. CAV arteries are surrounded by ectopic lymphoid structures (ELS) containing B cells and plasma cells. The aim of this study was to characterize the antigenic targets of antibodies produced in ELS. Coronary arteries and surrounding epicardial tissue from 56 transplant recipients were collected during autopsy. Immunofluorescence was used to identify antibody-producing plasma cells. Immunoglobulin levels in tissue lysates were measured by enzyme-linked immunosorbent assay and analyzed for donor-specific HLA antibodies by Luminex assay. Cytokine and receptor expression levels were quantified using quantitative polymerase chain reaction. Plasma cells in ELS were polyclonal and produced IgG and/or IgM antibodies. In epicardial tissue, IgG (p < 0.05) and IgM levels were higher in transplant patients with larger ELS than smaller ELS. In 4 of 21 (19%) patients with ELS, donor-specific HLA type II antibodies were detected locally. Cytokine and receptor expression (CXCR3, interferon γ and TGF-β) was higher in large ELS in the epicardial tissue than in other vessel wall layers, suggesting active recruitment and proliferation of T and B lymphocytes. ELS exhibited active plasma cells producing locally manufactured antibodies that, in some cases, were directed against the donor HLA, potentially mediating rejection with major consequences for the graft.

Plasma levels of alpha-1-antichymotrypsin are elevated in patients with chronic heart failure, but are of limited prognostic value

Background

There is increasing interest in utilising novel markers of cardiovascular disease risk in patients with chronic heart failure (HF). Recently, it was shown that alpha-1-antichymotrypsin (ACT), an acute-phase protein and major inhibitor of cathpesin G, plays a role in the pathophysiology of HF and may serve as a marker for myocardial distress.

Objective

To assess whether ACT is independently associated with long-term mortality in chronic HF patients.

Methods

ACT plasma levels were categorised into quartiles. Survival times were analysed using Kaplan-Meier curves and Cox proportional hazards regression, without and with correction for clinically relevant risk factors, including sex, age, duration of HF, kidney function (MDRD), ischaemic HF aetiology and NT-proBNP.

Results

Twenty healthy individuals and 224 patients (mean age 71 years, 72 % male, median HF duration 1.6 years) with chronic HF were included. In total, 159 (71 %) patients died. The median survival time was 5.3 (95 % CI 4.5–6.1) years. ACT was significantly elevated in patients (median 433 μg/ml, IQR 279–680) in comparison with controls (median 214 μg/ml, IQR 166–271; p < 0.001). Cox regression analysis demonstrated that ACT was not independently related to long-term mortality in chronic HF patients (crude HR = 1.03, 95 % CI 0.75–1.41, p = 0.871; adjusted HR = 1.12, 95 % CI 0.78–1.60, p = 0.552), which was confirmed by Kaplan-Meier curves.

Conclusion

ACT levels are elevated in chronic HF patients, but no independent association with long-term mortality can be established.

Current technologies for HER2 testing in breast cancer

BACKGROUND

Molecular techniques play an increasingly important role in breast cancer detection and help in the prediction of prognosis and treatment response. HER-2/neu predicts the sensitivity of breast tumors to trastuzumab and lapatinib. Presently there are several ways to assess HER2 status at the protein level (e.g. ELISA), at the RNA level (RT-PCR, microarray) and at the DNA level (fluorescence in situ hybridization, chromogenic in situ hybridization (ISH), silver in situ hybridization or multiplex ligation-dependent probe amplification).

DESIGN

This paper provides an overview of new developments in HER2 testing.

RESULTS

Although these techniques correlate well in comparative studies, discrepancies remain. Each technique has its own (dis)advantages and thus there is no real gold standard. Not surprisingly, there is no consensus at present on which of the protein- or gene-based techniques is superior, on the use of mono- or duo-probe ISH systems, nor on the use of manual or fully-automated staining- and scoring systems.

CONCLUSION

Until large clinical trials clearly point out one strategy as the best predictive one for trastuzumab response, the choice for a testing strategy will probably be based on local preferences which consider both practical and economic issues. Standardization, proper internal and external quality control assessment, laboratory accreditation and automation of tissue processing (autostainers) and interpretation methods (image analysis) will play an increasingly important role in HER2 testing.

Preemptive alloimmune intervention in high-risk pediatric acute lymphoblastic leukemia patients guided by minimal residual disease level before stem cell transplantation

Relapse of pediatric acute lymphoblastic leukemia (ALL) remains the main cause of treatment failure after allogeneic stem cell transplantation (alloSCT). A high level of minimal residual disease (MRD) before alloSCT has been shown to predict these relapses. Patients at risk might benefit from a preemptive alloimmune intervention. In this first prospective, MRD-guided intervention study, 48 patients were stratified according to pre-SCT MRD level. Eighteen children with MRD level >or=1 x 10(-4) were eligible for intervention, consisting of early cyclosporine A tapering followed by consecutive, incremental donor lymphocyte infusions (n=1-4). The intervention was associated with graft versus host disease >or=grade II in only 23% of patients. Event-free survival in the intervention group was 19%. However, in contrast with the usual early recurrence of leukemia, relapses were delayed up to 3 years after SCT. In addition, several relapses presented at unusual extramedullary sites suggesting that the immune intervention may have altered the pattern of leukemia recurrence. In 8 out of 11 evaluable patients, relapse was preceded by MRD recurrence (median 9 weeks, range 0-30). We conclude that in children with high-risk ALL, immunotherapy-based regimens after SCT are feasible and may need to be further intensified to achieve total eradication of residual leukemic cells.

T cells in cardiac allograft vasculopathy are skewed to memory Th-1 cells in the presence of a distinct Th-2 population

Cardiac allograft vasculopathy (CAV) in heart transplantation (HTx) patients remains the major complication for long-term survival, due to concentric neointima hyperplasia induced by infiltrating mononuclear cells (MNC). Previously, we showed that activated memory T-helper-1 (Th-1) cells are the major component of infiltrating MNC in coronary arteries with CAV. In this study, a more detailed characterization of the MNC in human coronary arteries with CAV (n = 5) was performed and compared to coronary arteries without CAV (n = 5), by investigating MNC markers (CD1a, DRC-1, CD3, CD20, CD27, CD28, CD56, CD68, CD69, FOXP3 and HLA-DR), cytokines (IL-1A, 2, 4, 10, 12B, IFN-gamma, and TGF-beta1), and chemokine receptors (CCR3, CCR4, CCR5, CCR7, CCR8, CXCR3 and CX3CR1) by immunohistochemical double-labeling and quantitative PCR on mRNA isolated from laser microdissected layers of coronary arteries. T cells in the neointima and adventitia of CAV were skewed toward an activated memory Th-1 phenotype, but in the presence of a distinct Th-2 population. FOXP3 positive T cells were not detected and production of most cytokines was low or absent, except for IFN-gamma, and TGF-beta. This typical composition of T-helper cells and especially production of IFN-gamma and TGF-beta may play an important role in the proliferative CAV reaction.

Chimerism analysis within 6 months of allogeneic stem cell transplantation predicts relapse in acute myeloid leukemia

The role of chimerism analysis as a prognostic indicator of relapse after hematopoietic stem cell transplantation (SCT) is controversial. We monitored chimerism status by short tandem repeat-based polymerase chain reaction (PCR) in T- and non-T-cell subsets and retrospectively evaluated clinical outcome in 96 patients with acute myeloid leukemia after myeloablative (MA) or reduced-intensity conditioning SCT. Fifty-six percent of 80 patients in the MA group demonstrated complete donor chimerism (CC) at all time points, whereas 6% had decreasing mixed chimerism (MC), 8% stable MC, 25% increasing MC and 3% increasing and decreasing MC. In 16 RIC patients, these percentages were 12, 50, 6, 6 and 19, respectively, together with 6% nonengraftment. Forty-three out of 96 patients experienced relapse. The last chimerism evaluation before relapse revealed increasing MC in only eight patients. In samples taken between 1 and 6 months post SCT, CC/decreasing MC was significantly related with a lower risk of relapse (31 versus 83%, P<0.000) and mortality (38 versus 83%, P<0.000) than with MC/increasing MC. However, the development of relapse was very rapid. Only very frequent monitoring of chimerism status by highly sensitive methods might identify impending relapse and allow early immunological intervention.

Apoptotic death of infiltrating cells in human cardiac allografts is regulated by IL-2, FASL, and FLIP

INTRODUCTION

In vitro studies have shown that apoptotic cell death is triggered by a IL-2-dependent activation of the Fas-FasL pathway and that this pathway can be inhibited by FLIP.

METHODS

To define whether FLIP regulates apoptotic death of graft infiltrating T-cells during IL-2-mediated rejection, we analyzed endomyocardial biopsies (EMB) from cardiac allograft recipients for CD3, DNA strand breaks (TUNEL assay), FLIP (mRNA and protein), and FasL mRNA expression.

RESULTS

Apoptosis was present in CD3+ T-cell infiltrates. The number of TUNEL-stained mononuclear cells was inversely correlated with FLIP mRNA expression levels (P=.09). FLIP protein was present in 5% to 10% of the infiltrating cells and was constitutively produced by cardiomyocytes irrespective of the rejection grade. Rejection biopsies had elevated IL-2 and FasL mRNA expression levels compared to the expression levels before and after acute rejection (P=.03 and P=.11), while FLIP mRNA expression levels were significantly decreased during rejection (P=.05).

CONCLUSION

Our results indicate that during the IL-2-induced rejection process, infiltrated T cells become more sensitive to apoptosis.

High level of chromosome 15 aneuploidy in head and neck squamous cell carcinoma lesions identified by FISH analysis: limited value of beta2-microglobulin LOH analysis

In cancer research, loss of heterozygosity (LOH), defined by microsatellite markers, is frequently used in the identification of gene loss. Especially, genomic alterations in the human leukocyte antigen (HLA) genes and the beta2-microglobulin (beta2m) gene on chromosome 15 are of interest regarding their function in the immune system. Because LOH analysis detects any allelic imbalance and not just allelic loss, we evaluated the LOH analysis in 11 head and neck squamous cell carcinoma (HNSCC) lesions using fluorescence in situ hybridization (FISH). The 11 tumors were selected out of 53 HNSCC lesions based upon beta2m LOH analysis and beta2m expression. Centromere 1 and 15 FISH were developed to determine the chromosome 15 copy number. Sequence-based mutation analysis of beta2m was conducted on tumors without beta2m expression; no mutations in the coding sequences were found. For five HNSCC lesions with LOH and beta2m expression, centromere 15 FISH indicated gain rather than loss. In the majority of the 11 HNSCC lesions, FISH showed centromere 1 and 15 heterogeneity throughout the tumor. Moreover, FISH indicated a more complex chromosome 1 and 15 distribution than could be concluded from microsatellite LOH analysis. Our results show that microsatellite LOH analysis does not represent the beta2m gene copy number and support the results obtained from comparative genomic hybridization (CGH) studies. Conclusions on genomic alterations in tumors cannot be based on LOH data only but depend on the results of immunohistochemical staining, FISH, and CGH.

Nonlethal transfusion associated graft-versus-host disease in a severe combined immunodeficient patient

An X-linked severe combined immunodeficient (SCID) patient received a nonirradiated erythrocyte transfusion and developed transfusion-associated graft-versus-host disease (TAGVHD), which was controllable with high-dose corticosteroids. Haplo-identical SCT was performed, after a myeloablative conditioning regimen. At day +26, he developed GVHD. Chimerism studies revealed DNA of the erythrocyte transfusion donor (ETD) and recipient only. Because of early nonengraftment and the presence of alloreactive T cells of ETD origin, the patient was treated with an immunosuppressive conditioning regimen followed by a second SCT from the same donor. While tapering immunosuppression, he again developed mild GVHD, and DNA of ETD and bone marrow donor origin were both present. On cyclosporin, the ETD-DNA signal finally disappeared. High-resolution HLA typing revealed haplo-identity between BMD, ETD and the patient, which might have contributed to the relative mild course of the TAGVHD.

Evidence for heterogeneity of T cell expansion in polymyositis and inclusion body myositis

Vbeta usage of muscle-infiltrating T lymphocytes in polymyositis (PM) and sporadic inclusion body myositis (s-IBM) was correlated with clinical and histopathological features. Immunohistochemical analysis was combined with complementarity-determining region 3 (CDR3) length analysis in nine muscle biopsies of eight PM patients and six biopsies of five s-IBM patients. Vbeta usage was heterogeneous in seven patients. Four of these patients had definite PM with endomysial located T cell infiltrates, but T cells specifically surrounding and invading individual non-necrotic fibers were not found. In two s-IBM patients, Vbeta 2 usage was increased. In one of them, a repeat biopsy showed a heterogeneous Vbeta usage. We conclude that clonal expansion of muscle-infiltrating T cells could only be detected in part of the patients. Explanations may be that clonal expansion does not take place in all disease phases and that PM is a heterogeneous disease with respect to pathogenesis.

Prognostic factors in localised prostate cancer with emphasis on the application of molecular techniques

Prostate cancer is the most prevalent malignancy in males in the Western world and the second leading cause of male cancer death. Prostate specific antigen (PSA) based screening and case finding leads to identification of early stage prostate cancer. It is often difficult to discriminate between patients that need curative treatment and those that can be managed conservatively. Prognostic factors are used to make this clinical decision. Based on the classification proposed by the American College of Pathologists and the World Health Organisation, selected prognostic factors in prostate cancer are described. Clinical applicable factors are stage, grade and serum PSA. Prognostic factors that are not routinely used (for various reasons) are ploidy, histological type and cancer volume in needle biopsies. All other factors (including circulating tumour cells, angiogenesis, growth factors, proliferation rate, apoptosis, nuclear morphometry, neuroendocrine differentiation, loss of chromosomal regions, tumour suppresser genes and adhesion molecules) are promising as prognostic factor although currently their use in clinical decisions is not recommended. The role of these factors in prostate cancer growth and their predictive value are discussed. The rapid developments in molecular techniques allow assessment of structure or function of thousands of genes in a prostate biopsy sample. We expect that molecular characterisation of tumour material will become a clinically important tool to predict prognosis in patients with localised prostate cancer.

Identification of human ccn2 (connective tissue growth factor) promoter polymorphisms

BACKGROUND

Connective tissue growth factor (CCN2; CTGF) is a newly identified growth factor, which is involved in the regulation of wound repair and fibrosis. Because there is variation among individuals with respect to tissue response to injury, genetic factors might be involved in the final outcome of tissue repair or scarring. For example, polymorphisms in the promoter region of genes, such as those encoding transforming growth factor beta1 (TGF-beta1), interleukin 10 (IL-10), and tumour necrosis factor alpha (TNF-alpha), influence transcriptional responses and are thought to contribute to the dysregulation of these genes in pathological conditions.

AIM

To investigate whether the promoter region of the ccn2 (ctgf) gene contains polymorphic sequences that might account for differential expression.

MATERIALS/METHODS

Seventy seven human DNA samples were sequenced-45 were from healthy controls and 32 were from patients with ischaemic heart disease (IHD)-using M13 tailed sequence specific ccn2 (ctgf) primers for amplification of a 600 bp fragment upstream of the transcription start site. Amplicons were bidirectionally sequenced with a dye primer M13 forward and reverse sequencing kit.

RESULTS

A C to G substitution was identified at position -132 in one of the patients with IHD. Moreover, in five of the 32 patients with IHD and in six of the 45 healthy controls, a G to C polymorphism was found at position -447. These substitutions at -132 and -447 are thought to lie within predicted binding domains for the transcription factors Pbx-1 and MZF1, respectively. In addition, insertions at position -43 (G), -47 (C), -71 (G) and a C to T substitution at position -198 were found in all DNA samples compared with the published ccn2 (ctgf) promoter sequence. These corrections do not involve sequences predicted to function as transcription factor binding sites.

CONCLUSION

Sequence analysis of the ccn2 (ctgf) promoter of 77 human DNA samples has revealed corrections and polymorphic sites. The latter lie within putative regulatory elements.

No association between IL-10 promoter gene polymorphism and heart failure or rejection following cardiac transplantation

Expression of interleukin (IL)-10 influences the frequency of rejection events after organ transplantation. Therefore, 70 heart transplant patients were genotyped for three single nucleotide polymorphisms and a microsatellite polymorphism in the promotor region of the IL-10 gene. The promoter region was amplified by polymerase chain reaction and genotyped by a colorometric oligo ligation assay and gene scan analysis, respectively. Patient groups consisted of patients suffering from dilated cardiomyopathy or ischaemic heart disease. Cardiac donors served as control group. No correlation was found between genotypes and heart failure or rejection after heart transplantation. This may indicate that in heart transplantation, the total balance of cytokine production is more important for post-transplant rejection activities than the levels of IL-10 as such.

Monitoring of residual disease and guided donor leucocyte infusion after allogeneic bone marrow transplantation by chimaerism analysis with short tandem repeats

In this study, we analysed the chimaeric status of peripheral blood leucocytes (PBLs) in recipients of allogeneic bone marrow transplantation (BMT) with the use of short tandem repeat (STR) microsatellite markers for monitoring the efficacy of BMT and donor leucocyte infusions (DLIs). A set of four STR markers was used with a highly discrimative capacity between individuals. STRs were detected by polymerase chain reaction (PCR) and were analysed by gene scanning (STR-GS). Between June 1990 and December 1998, 52 patients treated with BMT for chronic myeloid leukaemia (CML) were analysed. Seventeen patients relapsed after BMT and two patients never achieved remission after BMT. Fourteen of the 17 patients achieved a complete donor chimaerism after BMT, as detected by the presence of only donor STR-GS fragments, and in three cases a weak recipient STR-GS signal remained persistently detectable after BMT. A reappearance or increase of recipient STR-GS signals was indicative of relapse, which was mostly detected by STR-GS several months before relapse was diagnosed clinically. Nineteen patients were treated with DLI for reappearance of CML after BMT which resulted in complete remission in 17 patients, concordant with the disappearance of recipient STR-GS signals. More importantly, DLI treatment could be guided based upon the STR-GS data, which prevented unnecessary extra DLI courses that could cause toxicity. This study indicates that STR-GS is an effective and reliable method for monitoring BMT recipients.

Sentinel node biopsies in melanoma patients: a protocol for accurate, efficient, and cost-effective analysis by preselection for immunohistochemistry on the basis of Tyr-PCR

BACKGROUND

Immunohistochemistry (IHC) of serial sectioning is considered the gold standard for detection of melanoma activity in sentinel node (SN) biopsies. However, this is cost and labor intensive. In contrast, tyrosinase reverse transcription-polymerase chain reaction (RT-PCR) is simple and quick, but it is hampered by its extreme sensitivity. This study was performed to test whether a strategy that combines the two methods, using tyrosinase RT-PCR to preselect nodes for IHC, could be accurate and cost effective.

METHODS

In 36 patients, SNs were identified by scintigraphy and patent blue uptake. Of each SN, one cross section was analyzed first by hematoxylin and eosin staining. Next, all nodes were examined by serial sectioning and IHC of one-half and tyrosinase RT-PCR of the other. Before comparison, all results were documented in a blinded manner. Material costs and workload estimates were noted per SN.

RESULTS

Fifty-five SNs were retrieved from the 36 patients. Hematoxylin and eosin staining of the first cross section revealed tumor positivity in 3 patients (6 SN). Tyrosinase RT-PCR was positive in 11 of the remaining 33 patients (19 of 49 SN). Of these same 11 patients, only 5 were shown to have tumor-positive SNs by using IHC on serial sections (7 SN). All these nodes had been positive for tyrosinase on PCR. For IHC, an average of 40 sections were prepared and examined per SN at a cost of $200(U.S.)/SN. In contrast, routine tyrosinase RT-PCR costs $37(U.S.)/SN, and takes 5% of the time necessary for IHC. A strategy including hematoxylin and eosin staining on the first cross section, followed by tyrosinase RT-PCR on half of each negative (half) node, could preselect nodes to be taken through serial sectioning. In these series, such a strategy would have prevented serial sectioning and IHC of 30 SN from 22 patients. Apart from a considerable gain in efficiency, this would have reduced material costs by a minimum of $6000 (U.S.). This discrepancy would be even higher if work intensity of analysts and pathologists were considered.

CONCLUSIONS

In routine analysis of SN biopsies in melanoma patients, tyrosinase RT-PCR can be used effectively to preselect nodes for further IHC of serial sections. This method seems both time and cost effective.

Sequencing analysis of RNA and DNA of exons 1 through 11 shows p53 gene alterations to be present in almost 100% of head and neck squamous cell cancers

Data on p53 alterations in human cancers are mainly based on studies restricted to the core domain (exons 5-9), because mutations outside this region are assumed to be rare. To test this assumption, we studied 25 consecutive patients with primary, untreated head and neck squamous cell carcinoma (HNSCC) with a p53 mutation analysis strategy that consists of sequencing all 11 p53 exons and the complete p53 mRNA. With this method, we encountered p53 mutations in 91% of patients; 33% of these were located outside the core domain. Overexpression of the p53 protein was assessed with staining with antibody Bp 53-12-1. Protein overexpression was found in 64%. In one case, p53 overexpression occurred without p53 gene mutations. Analysis of tumor tissue from two autopsied patients with multiple lesions in the head and neck and at distant sites allowed analysis of the clonal relationship of the different tumor foci. In one patient, the head and neck lesion had a mutation different from the one observed at the distant sites, suggesting two different primary tumors, one of them leading to widespread metastastic disease. In all lesions from the second patient, the same mutation was found, suggesting one primary that had metastatized. It appears that sequencing of all exons of the p53 gene is vital for assessment of the real incidence of p53 mutations in HNSCC, because 33% of all mutations are located outside the core domain, leading to a mutation frequency of almost 100% in HNSCC. In 96% of cases, either presence or absence of p53 protein expression could be explained by the type of p53 gene mutation. When only analyzing the p53 core domain, the incidence of p53 mutations in HNSCC is underestimated.

Donor leukocyte infusions for recurrent hematologic malignancies after allogeneic bone marrow transplantation: impact of infused and residual donor T cells

We evaluated the efficacy and toxicity of different doses of donor T cells given with donor leukocyte infusions (DLI) as treatment for relapse of various hematologic malignancies after allogeneic bone marrow transplantation (BMT). We also studied whether DLI treatment was more effective if circulating T cells were exclusively of donor origin (complete donor T cell chimeras) as compared with T cells originating from both donor and recipient (mixed T cell chimeras). Twenty-eight patients were studied of whom 24 had a complete donor T cell chimerism. The malignancies were as follows: chronic myeloid leukemia (CML) in chronic phase (CP) (n = 9); more advanced CML (n = 5); multiple myeloma (MM) (n = 5); acute leukemia (AL) (n = 9). T cell doses varied from 0.1 x 10(7) to 33 x 10(7) T cells/kg. Eight patients received two to four DLI courses because they failed to respond to one course. Thirteen of 14 patients with CML, including four patients with more advanced CML, achieved complete remission (CR). All five patients with MM responded, including three CRs. Six patients (three with CML, three with MM) responded only after two to four DLI courses. Patients with CML-CP were likely to respond to as few as 1 x 10(7) T cells/kg whereas patients with MM generally responded when they received > or = 10 x 10(7) T cells/kg. However, despite the infusion of high T cell doses (up to 32 x 10(7) T cells/kg), practically all patients with AL failed to respond. The likelihood of response was strongly related to the occurrence of graft-versus-host disease (GVHD) in patients with CML and MM (P = 0.0002), although GVHD was not helpful for patients with AL. Higher T cell doses (> or = 10 x 10(7)/kg) induced serious GVHD (n = 17) and marrow aplasia (n = 5), and GVHD was directly or indirectly the cause of death for six patients. Finally, there were no obvious differences in responses between complete donor T cell chimeras and mixed T cell chimeras.

Adhesion molecule expression on skin endothelia in atopic dermatitis: effects of TNF-alpha and IL-4

BACKGROUND

Atopic dermatitis (AD) is characterized by skin infiltrates of leukocytes, such as lymphocytes and eosinophils.

OBJECTIVE

To describe the mechanisms determining this inflammatory process, we have analyzed expression of adhesion molecules and their regulation on skin endothelial cells (ECs).

METHODS

Expression of adhesion molecules on ECs was analyzed by immunohistochemistry by using Ulex europaeus agglutin 1 as a pan-endothelial marker.

RESULTS

Vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin were not found in skin of nonatopic individuals, whereas expression of these surface molecules was observed in nonlesional skin of patients with AD and was even more pronounced in lesional skin or after epicutaneous application of aeroallergen. Induction of adhesion molecule expression was examined on both macrovascular ECs from human umbilical cord vein (HUVECs) and human microvascular ECs (HMEC-1) from skin. TNF-alpha very potently upregulated adhesion molecule expression in vitro on both EC cell types. To verify the in vivo relevance of TNF-alpha, we performed TNF-alpha staining in the skin. TNF-alpha was observed in the dermis of nonatopic skin, both in chymase-containing mast cells and CD68+ macrophages. The increase in the number of TNF-alpha-containing cells was concomitant with the increase in adhesion molecule expression in the skin of patients with AD. IL-4 is supposed to be important in atopic diseases because of its IgE- and VCAM-1-inducing properties. However, IL-4 addition failed to induce VCAM-1 expression on HMEC-1, although in the same set of experiments, a clear induction of VCAM-1 expression by IL-4 on HUVECs was demonstrated. Flow cytometry revealed the absence of 11-4 receptor alpha-chains on HMEC-1 and their presence on HUVECs. Immunohistochemistry examination on skin sections showed no binding of the IL-4R alpha-chain antibodies to ECs.

CONCLUSION

We conclude that adhesion molecule expression is increased in the skin of patients with AD. Most probably, this increased expression is not a (direct) effect of IL-4 on skin endothelium, but other cytokines, such as TNF-alpha, might be responsible for this increased adhesion molecule expression. Continuous adhesion molecule expression may facilitate T-cell extravasation in a nonantigen-specific manner, thus explaining the presence of increased T-cell numbers in nonlesional skin of patients with AD.

Long-lived Th2 clones specific for seasonal and perennial allergens can be detected in blood and skin by their TCR-hypervariable regions

We investigated the longevity of allergen-specific Th cells derived from patients suffering from either allergic rhinitis or atopic dermatitis. T cell clones (TCC) specific for seasonal and perennial allergens were raised. To determine whether these TCC were long-lived in vivo, PBMC and allergen-specific polyclonal T cell lines, collected and established inside a period of up to 4 years, were screened for the TCC of interest. For this purpose, a T cell tracing protocol was established in which oligonucleotides specific for the TCR beta-chain hypervariable junctional region were used as tools to identify each particular TCC. Seven pollen-specific TCC and two house dust mite-specific TCC, with a Th2-like cytokine production pattern in vitro, were demonstrated to be long-lived memory T cells in vivo. Specificity of the tracing protocol was ascertained by TCR sequence analysis. We conclude that allergen-specific TCC can persist for years, evidence for which can be monitored in blood, but also in the target organ of the allergic disorder. The data indicate that in vitro-characterized, allergen-specific, long-lived TCC may well reflect a repertoire of T lymphocytes of pathogenetic importance in vivo.

Release of cytokines and soluble cell surface molecules by PBMC after activation with the bispecific antibody CD3 x CD19

Bispecific antibodies (BsAb) consist of two different heavy and light chains and may bind to two different antigens present on different cell types. With their dual specificity BsAb may recognize effector cells (e.g. T cells) on one hand and tumour cells (e.g. malignant B cells) on the other hand. The authors analysed whether T cell activation and subsequent killing of malignant B cells mediated by the bispecific antibody CD3 x CD19 was reflected by the release of cytokines. In addition, the authors investigated whether the in vitro cytokine release was similar to that observed in vivo in the patients treated with BsAb. The in vitro release of cytokines into the supernatant of cell cultures of peripheral blood mononuclear cells (PBMC) and malignant B cells was measured after incubation with either the bispecific antibody CD3 x CD19 or the monospecific anti-CD3 (aCD3) antibody in the presence or absence of interleukin (IL)-2. Release of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-6, IL-8, IL-10, soluble (s) CD4, sCD8 and sCD25 by PBMC was equal under both conditions and could be used as an indicator for T cell activation. However, the cytokine pattern and level did not correlate with the cytotoxic capacity, which was 4 logs higher with BsAb + IL-2 compared to aCD3 + IL-2. The in vitro pattern of cytokine release was similar to that observed in vivo in the serum of patients treated with BsAb and IL-2, indicating the possibility of predicting cytokine release in future patients with other therapeutic regimens.

B7-1 (CD80) as target for immunotoxin therapy for Hodgkin's disease

In this preclinical study, the potential applicability of an anti-B7-1 immunotoxin (IT) for the treatment of Hodgkin's disease (HD) was investigated. Immunohistochemical analysis demonstrated strong expression of B7-1 on Hodgkin and Reed-Sternberg (R-S) cells and clear expression on dendritic cells, macrophages and some B-cells in tissues, but not on other tissue cells. Flow cytometric analysis demonstrated that B7-1 was expressed on a few monocytes, but not on CD34+ cells from bone marrow, resting T- or B-cells from peripheral blood or epithelial and endothelial cell lines. An anti-B7-1 immunotoxin containing the anti-B7-1 monoclonal antibody (MAb) B7-24 and saporin as toxin moiety was constructed and showed an affinity similar to that shown by the native MAb. It exhibited strong cytotoxicity against the B7-1+ B-cell line Raji (IC50 10(-11) M), R-S cell lines HDLM2, KM/H2 and L428 and also against a B7-1-transfected epithelial cell line, A431, whose parental line lacks expression of B7-1. In clonogenic assays with Raji cells or KM/H2 cells, a 3- or 4-log kill, respectively, was observed. No cytotoxicity was found against the B7-1- epithelial and endothelial cell lines or against haematopoietic progenitor cells. In conclusion, an anti-B7-1 immunotoxin was developed that had good cytotoxicity against R-S cell lines and that may be used in the elimination of R-S cells in vivo. A concomitant elimination of activated antigen-presenting cells may avoid development of antitoxin and anti-mouse Ig responses and allow repeated administration.

Cutaneous malignant melanomas in 57 cats: identification of (amelanotic) signet-ring and balloon cell types and verification of their origin by immunohistochemistry, electron microscopy, and in situ hybridization

Cutaneous malignant melanomas in cats, both melanotic and amelanotic, were diagnosed in 57 of 1.530 skin tumors during the period 1991-1995. All melanomas occurred in domestic shorthaircats of ages 3-19 years (mean = 11.5 years). Postmortem examination was performed on 16 cats. All had metastases in the regional lymph node and several organ systems. The average time of survival after surgical removal of the tumor was 4.5 months. Histologically, five types of melanomas could be distinguished: epithelioid, spindle, mixed, signet-ring, and balloon cell. Whereas all epithelioid, spindle, and mixed epithelioid/spindle cell types showed pigmentation, signet-ring and balloon cell types were often amelanotic. Immunohistochemical examination of the melanomas revealed a positive staining for S-100, vimentin, and neuron-specific enolase. The melanomas were negative for muscle cell markers, except in some of the signet-ring cell melanomas; 13 of 21 tumors showed a weak positive staining for polyclonal desmin. Electron microscopic examination of signet-ring cell melanomas revealed an abundance of intermediate filaments, whereas in some of these tumors a few cells with melanosomes were found. Nonisotopic in situ hybridization for mRNA encoding for tyrosinase verified the melanocytic origin of the amelanotic signet-ring and balloon cell melanomas.

Immunohistochemical demonstration of cellular antigens of the cat defined by anti-human antibodies

A panel of monoclonal antibodies (mAb) and some polyclonal rabbit sera directed against human antigens were studied on cryostat tissue sections of three cats using immunohistochemistry. Reactivity of the antibodies was tested on feline tonsil, intestine, thymus, lymph node and spleen with a three-step immunoperoxidase technique and compared with reactions on human thymus, lymph node and spleen. From a total of 95 antibodies, 28 gave reactivity comparable with that in human tissues. The remaining antibodies gave none or miscellaneous results. The positive reactions in the cat included antibodies directed to adhesion molecules (VLA-2 and VLA-4), to natural killer (NK) cells (CD56, CD57 and NCAM), to complement receptor CR1, to proliferation marker Ki-67 (MIB-1), to endothelial antigens (EN-4, PAL-E and von Willebrand factor) and to structural proteins like vimentin, desmin, collagen type IV and cytokeratin. The identification of these cross-reacting antibodies extends the spectrum of immunological reagents that are now available for the cat, and will thus contribute to the study of the feline immune system.

Complete donor T cell chimerism is accomplished in patients transplanted with bone marrow grafts containing a fixed low number of T cells

T cell depletion of the bone marrow graft, the most effective method to prevent severe graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT), has resulted in approximately three times more relapses of the disease post-transplant than after non-T cell-depleted BMT. It has been hypothesized that this is caused by the development of mixed T cell chimerism, often observed after T cell depleted BMT, whereas non-T cell-depleted BMT generally results in complete donor T cell chimerism. In order to find an approach of T cell depletion which may avoid the high relapse rate but prevent severe GVHD, we gave marrow recipients a partial T cell-depleted marrow graft containing 1 x 10(5) donor T cells/kg recipient's weight. To investigate whether our approach results in complete donor T cell chimerism, we analyzed post-transplant the origin of purified T cells in 56 patients with hematologic malignancies, including 15 patients at the time they relapsed. The T cells were studied for being of host or donor origin by amplification of four loci of variable number of tandem repeats (VNTR) by PCR. From 6 months post-BMT, all 45 patients who could be analyzed in remission (five had died and six had relapsed within 6 months) had T cells that were exclusively of donor origin. Furthermore, the T cells of 15 patients who had relapsed post-BMT were also exclusively of donor origin. Severe GVHD was never observed. Thus, this approach seems to combine the favorable aspects of both T cell-depleted and non-T cell-depleted BMT.

Epidermal growth factor receptor expression in pancreatic lesions induced in the rat by azaserine

In the present study, the expression of the epidermal growth factor receptor (EGFR) was investigated in putative preneoplastic and neoplastic acinar cell lesions induced in the rat pancreas by azaserine, using Northern blotting, in situ hybridisation (ISH) and immunohistochemistry. EGFR protein levels were decreased in putative preneoplastic eosinophilic acinar cell lesions (atypical acinar cell nodules, AACN) in comparison with normal acinar cells of the pancreas. However, EGFR mRNA expression correlated positively with the volume of AACN in pancreatic homogenates and ISH showed equal or stronger EGFR mRNA expression in AACN than in the surrounding normal acinar cells. Neither EGFR protein nor EGFR mRNA was detected in more advanced lesions such as acinar adenocarcinomas (in situ). Moreover, EGFR protein expression showed an inverse relationship with the mitotic rate of the acinar cells. These findings suggest that down-regulation of EGFR at the protein level may abrogate negative constraints on cell growth, which may stimulate the development of putative preneoplastic AACN to more advanced lesions and, ultimately, acinar adenocarcinomas.

Overexpression of transforming growth factor-alpha and epidermal growth factor receptor, but not epidermal growth factor, in exocrine pancreatic tumours in hamsters

Using immunohistochemistry, Northern blotting and a semi-quantitative PCR technique, epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) expression were studied in the pancreas of N-nitrosobis(2-oxopropyl)-amine (BOP)-treated hamsters. After initiation pancreatic carcinogenesis was modulated by a high fat diet or by injections with the cholecystokinin analogue caerulein. Autopsies were performed 6 and 12 months after the last injection with BOP. Immunohistochemistry revealed a weak expression of TGF-alpha in nomal acinar cells and a stronger expression in ductular and centro-acinar cells. Over-expression of TGF-alpha was observed in advanced putative preneoplastic lesions (classified as borderline lesions) and in ductular adenocarcinomas. EGFR immunoreactivity was present only in ductular adenocarcinomas. EGF peptide expression was observed both in acinar and ductular normal and tumorous cells and the level of expression did not change significantly during carcinogenesis. Moreover, the post-initiation treatments did not cause differences in EGF, TGF-alpha or EGFR peptide or mRNA levels, except for a significantly lower expression of TGF-alpha mRNA in hamsters fed a high fat diet when compared with those fed a low fat diet. TGF-alpha mRNA levels increased, whereas EGF mRNA levels decreased significantly in total pancreatic homogenates of BOP-treated hamsters in comparison with untreated controls. Also, in ductular adenocarcinomas TGF-alpha and EGFR (but not EGF) mRNA levels were significantly higher than in normal pancreatic homogenates. In pancreatic homogenates obtained 6 months after the last BOP injection, these differences were less pronounced in comparison with those obtained after 12 months. The present results indicate that TGF-alpha (but not EGF) might act in a paracrine or autocrine manner in pancreatic tumours in BOP-treated hamsters via simultaneously expressed EGFR. However, TGF-alpha, EGF and EGFR do not seem to be involved in the modulating effects of a high fat diet or caerulein treatment on pancreatic carcinogenesis in BOP-treated hamsters.

Expression of two interleukin 4 mRNA isoforms in B lymphoid cells

Expression of an alternative spliced IL4 mRNA was found in in vitro activated T cells. In this study we show that the expression of IL4 mRNA, as well as the expression of this alternatively spliced form of IL4 mRNA, is not restricted to these cells. We analyzed different human lymphoid tissues and cell lines of different origin and found that the alternatively spliced IL4 transcripts are also expressed in human lymphoid tissues, in purified B cells, in the various B cell-derived cell lines, and even in nonlymphoid cell lines. Stimulation with the phorbol ester PMA enhanced expression of both transcripts in all cells studied. The two IL4 transcripts were cloned and sequenced from the B cell line Namalwa. In the alternatively spliced form, the same exon 2 is deleted as has been observed in in vitro activated T cells. In principle, such alternatively spliced mRNA may give rise to a truncated IL4 protein, as the deletion does not result in a frameshift. We tested supernatants of activated PBMC, cell lines, and cell extracts for the presence of IL4 protein. We found IL4 protein expression in activated PBMC, but not in any of the stimulated cell lines or in the purified B cells. Using a modified in situ hybridization method with Dig-labeled PCR products, however, these cells did express IL4 mRNA. This shows that transcription of both IL4 forms is not restricted to T cells and can be induced in other cell types as well. Using these non-T cells, no protein has been found in the supernatant, however. It is possible that transcription of the IL4 gene is not necessarily followed by translation and that translation into the IL4 protein requires an additional signal.

Transforming growth factor-alpha and epidermal growth factor expression in the exocrine pancreas of azaserine-treated rats: modulation by cholecystokinin or a low fat, high fiber (caloric restricted) diet

Expression of transforming growth factor-alpha (TGF-alpha) and epidermal growth factor (EGF) was studied in normal pancreatic tissue and in (pre)neoplastic pancreatic lesions of azaserine-treated rats. They were given either a low fat, high fiber (low caloric) diet, to inhibit carcinogenesis, or a low fat diet combined with injections of the cholecystokinin analog caerulein to enhance carcinogenesis. The control groups, maintained on a low fat diet, were injected with azaserine or were not treated at all. Autopsy was performed at 6 and 15 months after the last azaserine injection. After both 6 and 15 months immunohistochemistry revealed a weak expression of EGF and TGF-alpha peptides in the acinar cells, and a stronger expression in the ductular and centroacinar cells. TGF-alpha peptide expression was reduced in both putative preneoplastic and neoplastic acinar cell lesions, but no differences in EGF peptide expression were observed between the various stages of exocrine pancreatic carcinogenesis. After 16 months an increase in TGF-alpha mRNA due to treatment with azaserine was detected by semi-quantitative PCR in total pancreatic homogenates, whereas EGF mRNA expression had decreased. TGF-alpha mRNA levels in macroscopically isolated tumors were significantly lower, but EGF mRNA levels were significantly higher, than in total pancreatic homogenates from azaserine-treated rats. Furthermore, EGF and TGF-alpha mRNA levels in isolated tumors did not differ significantly from mRNA levels in non-carcinogen-treated rats. Neither with immunohistochemistry nor with PCR were differences in EGF or TGF-alpha expression observed due to either inhibition or stimulation of carcinogenesis. It is concluded that putative preneoplastic acinar cell lesions induced in rat pancreas by azaserine may develop into acinar adenocarcinomas independently of TGF-alpha and EGF. The results suggest involvement of these growth factors at the early stage of the carcinogenic process, during the initiation of normal acinar cells into putative preneoplastic cells. However, modulation of azaserine-induced pancreatic carcinogenesis by cholecystokinin or a low fat, high fiber (caloric restricted) diet appeared not to be regulated by EGF or TGF-alpha.

Prevention of donor-specific T-cell unresponsiveness after buffy-coat-depleted blood transfusion

The immunosuppressive effect of blood transfusions has been demonstrated in several clinical studies. The effect is probably mediated by HLA-class-II-bearing donor leucocytes, because results from laboratory tests show specific down-regulation of the recipient's T-Cell response after administration of blood from donors sharing one HLA haplotype with the recipient. In the present study we evaluated the immunosuppressive potential of buffy-coat-depleted red cell transfusions in patients waiting for renal transplantation, by measuring the frequency of cytotoxic precursor T cells before and after transfusion. The buffy coat was removed from whole blood by the Optipress system and resulted in > 97% depletion of lymphocytes and monocytes. A single transfusion of HLA-haplotype-matched buffy-coat-depleted red cells induced donor-specific down-regulation of T-cell responses in only two of 14 patients. Since HLA-class-II-bearing cells are also involved in the induction of anti-HLA antibodies, we evaluated retrospectively the incident of HLA alloimmunization after a single transfusion of buffy-coat-depleted red cells. No anti-HLA antibodies were found in 140 patients at risk for primary immunization. We conclude that the poor immunological responses found after a single transfusion of HLA-haplotype-matched buffy-coat-depleted red cells is due to the small number of residual HLA-class-II-bearing donor cells. This blood component should not be used for induction of immunosuppression.

CD8 T cell activation after intravenous administration of CD3 x CD19 bispecific antibody in patients with non-Hodgkin lymphoma

A bispecific antibody directed to T and B cells (CD3 x CD19 bsAb) was daily infused intravenously in escalating doses from 10 micrograms up to 5 mg in three patients with chemotherapy-resistant non-Hodgkin lymphoma; in this way we aimed to activate T cells to kill the malignant B cells. Only limited toxicity was observed, consisting of moderate fever preceded by chills or shivers and mild thrombocytopenia. No human anti-(mouse Ig) antibodies were found. Pharmacokinetics showed a t1/2 of 10.5 h with peak levels of 200-300 ng/ml after infusion of 2.5 mg bsAb. bsAb in serum was functionally active in vitro. After bsAb infusion a rise in serum tumour necrosis factor alpha was observed, accompanied by an increase in soluble CD8 and to some extent in soluble interleukin-2 receptor (IL-2R), but not in interferon gamma. IL-4 or soluble CD4. No evidence was found for monocyte activation (no increases in IL-6, IL-8 or IL-1 beta in serum). No gross changes in histology or number of IL-2R+, CD4+ or CD8+ cells were found in the lymph nodes after therapy, but one patient showed activated CD8+ T cells within the tumour nodules. In conclusion, after intravenously administered CD3 x CD19 bsAb only moderate toxicity was found, probably due to CD8+ T cell activation and cytokine release, without CD4+ T cell activation.

An improved, sensitive, non-radioactive in situ hybridization method for the detection of cytokine mRNAs

We established an improved non-radioactive in situ hybridization (ISH) method to detect mRNA of cytokines in cell preparations and tissues. Via this method we could demonstrate various cytokines in stimulated peripheral blood mononuclear cells (PBMC), lymphoid cell lines and human lymphoid tissues. The probes for the in situ hybridization were made by labelling cytokine-specific PCR products with digoxigenin (Dig) in a repeated PCR. This resulted in an intrinsic labelling of the probe with several Dig-UTP molecules. Incorporation of Dig-11-dUTPs was shown on ethidium bromide-stained agarose gels by a higher molecular weight of the PCR products with incorporated Dig-dUTPs when compared to control PCR products without digoxigenin. Cytospin-centrifuged cells of PHA-stimulated PBMC or lymphoid cell lines and frozen sections of various human lymphoid tissues were hybridized with the Dig-labelled cytokine probes and the hybridized probes were detected immuno-histochemically. In this way, we detected and localized cytokine mRNAs (IL-2, IL-4, IL-6, IL-8, IL-10) in PBMC, in the human T-cell line Jurkat, in the follicular lymphoma cell line DoHH2, and in human lymph nodes and tonsils. The in situ hybridization had a high sensitivity as the results correlated closely with the detection of cytokine mRNA by reverse transcriptase-PCR (RT-PCR) data from the same samples. We showed that Jurkat and DoHH2 cells produce several cytokines constitutively and that, after activation with the phorbol ester PMA, expression of several cytokine mRNAS was enhanced.

Protein tyrosine phosphatase activity as a diagnostic parameter in breast cancer

Cellular phosphotyrosine levels are regulated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). It is supposed that this balance is disturbed in tumour cells, making the increased or altered activity of PTKs and PTPs likely hallmarks of tumour tissues. Indeed it could be shown that the PTK activity was increased in breast cancer in correlation with prognosis (Hennipman et al., Cancer Res. 49, 516-522, 1989). In the present report we measured the PTP activities in breast cancer and normal breast tissues. An increase of approximately three- to four-fold was measured in the cytosolic tumour fractions compared to normal, whereas the solubilized membrane fraction PTP activity showed an increase in tumours of approximately 1.5-fold. Remarkably, the membrane PTP activity correlated with the presence of tumour positive axillary lymph nodes (p = 0.004), whereas the cytosolic PTP activity correlated with the mitotic index, a higher PTP activity occurring when the mitotic index was higher than 10 (p = 0.0004). These results indicate the membrane PTP activity may be considered as an index of metastatic potential, whereas cytosolic PTP activity may be a measure of the growth capacity of the tumour. The increase of PTP activity in breast cancers was confirmed by enzyme-histochemical studies. In frozen sections of tumours a strong to moderate activity was found in both tumour cells and interstitial cells. In the interstitium membrane activity was most pronounced, whereas in the tumour cells diffuse staining of the cytoplasm together with a clear membrane staining was demonstrated. Immunoblotting with anti-phosphotyrosine antibodies also reveals differences between the tumours and normal tissues, confirming the disturbance of the balance between protein tyrosyl phosphorylation and dephosphorylation in the tumour cells.

Reduction of donor-specific cytotoxic T lymphocyte precursors in peripheral blood of allografted heart recipients

Tolerance to allografted hearts in human recipients has been observed both in clinical situations and in in vitro experiments. To elucidate whether a quantitative change of alloreactive CTL is one of the mechanisms accounting for this graft tolerance, CTL precursor (CTLp) frequencies in the peripheral blood of 10 heart recipients were measured against spleen cells from donors and HLA nonidentical third-party persons. In this longitudinal follow-up study, we showed that the rejection reaction(s) in the grafted heart correlated with CTLp frequencies in samples taken before transplantation against the donor spleen cells, but not with the CTLp frequencies against the spleen cells from the third-party persons. The CTLp frequencies against the spleen cells from donors decreased 4-6 months after transplantation, and remained at a low level afterward. However, the CTLp frequencies against spleen cells from third-party persons in blood samples obtained 1 year after transplantation were not significantly different from those before transplantation. Therefore, we conclude that donor-reactive CTLs are important in rejecting allografted heart. The decrease in donor-specific CTLp after transplantation could explain the donor-specific tolerance. The decrease may be due to homing of the specific CTLp to the graft, or by clonal deletion of the donor-reactive CTL caused by chronic alloantigen stimulation in the presence of immunosuppressive therapies.

Lymphocytes at tumor margins in patients with head and neck cancer. Relationship with tumor size, human lymphocyte antigen molecules, and metastasis

A series of 76 patients with head and neck squamous cell carcinoma (HNSCC) was analyzed for the significance of a peritumoral lymphocytic infiltrate (PLI). The composition of PLI was immunohistochemically investigated in frozen material and correlated with other putative prognostically significant variables. PLI was shown to be correlated with the invasion pattern but not with any of the other investigated variables such as tumor size, thickness, and metastasis. However, individual components of PLI were statistically significant: human lymphocyte antigen (HLA)-class II-positive cells correlated with occurrence of metastasis, and CD22-positive cells correlated with tumor size. We conclude that studies on the significance of PLI in HNSCC patients should concentrate on analysis of its individual components.

Primary tumor cells of myeloma patients induce interleukin-6 secretion in long-term bone marrow cultures

Long-term bone marrow cultures (LTBMC) from patients with multiple myeloma (MM) and normal donors were analyzed for immunophenotype and cytokine production. Both LTBMC adherent cells from myeloma and normal donor origin expressed CD10, CD13, the adhesion molecules CD44, CD54, vascular cell adhesion molecule 1, very late antigen 2 (VLA-2), and VLA-5, and were positive for extracellular matrix components fibronectin, laminin, and collagen types 3 and 4. LTBMC from myeloma patients and normal donors spontaneously secreted interleukin-6 (IL-6). However, levels of IL-6 correlated with the stage of disease; highest levels of IL-6 were found in LTBMC from patients with active myeloma. To identify the origin of IL-6 production, LTBMC from MM patients and normal donors were cocultured with BM-derived myeloma cells and cells from myeloma cell lines. IL-6 was induced by plasma cell lines that adhered to LTBMC such as ARH-77 and RPMI-8226, but not by nonadhering cell lines U266 and FRAVEL. Myeloma cells strongly stimulated IL-6 secretion in cocultures with LTBMC adherent cells from normal donors and myeloma patients. When direct cellular contact between LTBMC and plasma cells was prevented by tissue-culture inserts, no IL-6 production was induced. This implies that intimate cell-cell contact is a prerequisite for IL-6 induction. Binding of purified myeloma cells to LTBMC adherent cells was partly inhibited by monoclonal antibodies against adhesion molecules VLA-4, CD44, and lymphocyte function-associated antigen 1 (LFA-1) present on the plasma cell. Antibodies against VLA-4, CD29, and LFA-1 also inhibited the induced IL-6 secretion in plasma cell-LTBMC cocultures. In situ hybridization studies performed before and after coculture with plasma cells indicated that LTBMC adherent cells produce the IL-6. These results suggest that the high levels of IL-6 found in LTBMC of MM patients with active disease are a reflection of their previous contact with tumor cells in vivo. These results provide a new perspective on tumor growth in MM and emphasize the importance of plasma cell-LTBMC interaction in the pathophysiology of MM.

Immunohistochemical demonstration of bcl-2 protein in human tooth germs

This study sought to detect patterns of bcl-2 protein expression that could provide more insight into the cellular dynamics of tooth development. As bcl-2 serves to prevent cell death, its occurrence in odontogenic tissues might be helpful in identifying cell populations from which odontogenic tumours may arise. The bcl-2 protein was found only in the epithelial part of the tooth germ and was present in all parts of the enamel organ except the ameloblast. This suggests that bcl-2 protein plays a part in maintaining the viability of the enamel organ. The presence of bcl-2 in the fully matured tooth germ and adjacent dental lamina might indicate that epithelial odontogenic tumours may originate from various parts of the enamel organ.

Interaction of tumour cells with cultured stromal cells from human bone marrow

Adhesion of tumour cells to cultured bone marrow stromal cells has been studied in an in vitro model system. Stromal cells were isolated from bone marrow aspirates. Immunohistochemical and electron microscopical analysis revealed a uniform cell monolayer of myofibroblastic cells, expressing fibroblast antigens and smooth muscle actin. Cell interactions with tumour cells lines showed different patterns. The K562 cells bound in low numbers to stromal cells. HEL-DR- and HL60 cells adhered to stromal cells showing an enlarged cell contact area (spreading) attenuated by distinct contact sites and they invaded the monolayer. Adhesion molecules, important for cell contacts, were detected on tumor cells. Different VLA antigens were detected on tumour cells, but on stromal cells only VLA-5 and CD29 were found. In vitro inhibition studies with mAbs against adhesion molecules indicated two major pathways for binding of tumour cells to stromal cells: VCAM-1/VLA-4 and fibronectin/VLA-5. Variation in inhibition of mAbs to VLA-4 and VCAM-1 indicated the existence of critical epitopes in the adhesion of tumour cells.

Encoded latent membrane protein 1 of Epstein-Barr virus on follicular dendritic cells in residual germinal centres in Hodgkin's disease

AIMS

To determine if there is an association between Epstein-Barr virus (EBV) infection and Hodgkin's disease.

METHODS

Fifty cases of Hodgkin's disease and 25 reactive lymph nodes were screened for the presence of EBV-RNA (EBER) using in situ hybridisation, and for the expression of EBV encoded latent membrane protein 1 (LMP-1) by immunohistochemistry.

RESULTS

In 42% of the cases of Hodgkin's disease, EBER was detected in the nuclei of the malignant cells, and in LMP-1 expression was found 36%. Both EBER and LMP-1 positivity were seen in 34% of the cases. An additional finding was the presence of LMP-1 on follicular dendritic cells in residual germinal centres in two cases of Hodgkin's disease. EBER was not detected in these germinal centres. In reactive lymph nodes only occasional EBER positive, small, lymphoid cells were found, without LMP-1 expression.

CONCLUSIONS

These results show a strong correlation between the presence of EBER and the LMP-1 expression in the Reed-Sternberg cells. They corroborate a role for EBV in at least some cases of Hodgkin's disease. LMP-1 is probably presented as an immune complex in the germinal centres, as part of an immune response against EBV.

Thoughts on the thymus and the T-lymphocyte repertoire. Relevance to the tolerance of the immune response

The thymus is a central lymphoid organ, and has one important function in the immune system. It generates immunocompetent T (= thymus-dependent) cells. 'Immunocompetence' is the single most important characteristic acquired during the differentiation process of T-cells, from progenitor cell in the bone marrow to mature cell in peripheral lymphoid organs and blood. The basis of competence is recognition, mediated by the T-cell receptor on the cell surface. Using this receptor, T-cells recognize antigens only in the form of antigenic fragments complexed with molecules of the major histocompatibility complex. Within the thymus, progenitor cells rearrange gene segments encoding the various parts of the receptor molecule. After expression of all possible receptors (the potentially available repertoire) selection processes occur, yielding only those T-cells that have a receptor by which antigens can be recognized together with molecules of the major histocompatibility complex, and that do not recognize autoantigens (the actual repertoire). This process of selection is considered as a unique function of the thymus. In this review, first some histophysiological aspects of the thymus are described. Next, the events that occur during the sojourn of the lymphocytes in the thymus are presented. Finally, these data are considered with regard to thymic abnormalities. These include acute and age-associated involution, and the generation of autoimmune reactivity due to disturbed intrathymic selection.

Expression of T-cell receptor alpha and beta variable genes in normal and malignant human T cells

A PCR method was developed to analyse each of 29 families of the T cell receptor V alpha gene and 20 families of the V beta gene at the mRNA level in heterogenous cell populations. All V alpha and V beta families were detectable in blood mononuclear cells from four of six healthy donors. In two donors only V alpha 22 was missing, and all other V alpha and V beta families were detected. V beta family expression was observed in T-leukaemic cell lines Jurkat, HSB, Molt-3 and Molt-4. In contrast, V alpha family expression was not detectable in any cell line except Jurkat cells. In T-cell malignancies (non-Hodgkin's lymphoma and mycosis fungoides), one or two V alpha and V beta families were detectable. Four of 10 cases investigated showed two V alpha transcripts and one V beta transcript. This fits with concepts in literature that allelic exclusion for the genes encoding alpha chains is not strictly required in the DNA rearrangement, or that this exclusion is a post-translational event. Using a limited series of antibodies to V beta gene family products, blood mononuclear cells from healthy donors were analysed by flow cytometry in a follow-up study. Two of four donors were rather stable in proportions of T cells expressing distinct V beta families, and two other donors showed variation in one or more families. When analysed on frozen tissue sections of normal lymph node and tonsil, there was no preferential location of lymphocytes expressing a distinct V beta gene family in different compartments (interfollicular area, follicle, or tonsillar epithelium).

Expression of the first calcitonin/CGRP gene in spontaneous and transplanted rat medullary thyroid carcinoma: a comparison of dot-blot analysis, in situ hybridization, and immunohistochemistry

Calcitonin (CT) and calcitonin gene-related peptide (CGRP) are encoded by a single gene, the CALC-I gene. They are expressed in the thyroid and in the nervous system by alternative splicing of the pre-messenger RNA derived from the CALC-I gene. In medullary thyroid carcinoma (MTC), a malignancy derived from the calcitonin-producing C-cells in the thyroid, production of calcitonin and CGRP is a common feature. We investigated the CT and CGRP production of four spontaneous MTCs transplanted three to four times and 14 MTC lines transplanted for several years in WAG/Rij rats, a strain with hereditary MTC. The expression of CT and CGRP in the spontaneous and in the transplanted tumors was studied by means of RNA in situ hybridization (RISH), dot-blot analysis, and immunohistochemistry. A down-regulation of CT production in transplanted compared with spontaneous tumors was observed, but an inverse relation between CT and CGRP mRNA content in both spontaneous and transplanted tumors was not observed. In this study, RISH proved to be as sensitive as dot-blot analysis to detect gene expression in tissue samples. The different approaches of analyzing the gene expression in tissue samples (the cellular localization of gene expression by ISH vs the analysis of an extract of a total tissue sample with dot-blot analysis) showed that each technique is equal in value and that they are complementary to each other.

T-cell receptor V beta-family usage in primary cutaneous and primary nodal T-cell non-Hodgkin's lymphomas

To evaluate whether the expression of T-cell receptor (TCR) V beta families in eight cases of malignant T-cell lymphomas took place in a preferential manner, we analyzed four cases of mycosis fungoides (MF), the most common form of primary cutaneous T-cell non-Hodgkin's lymphomas (NHL), and four cases of primary nodal T-cell NHL. The usage of V beta families in T-cell populations was investigated on mRNA that was transcribed to cDNA using a C beta primer and reverse transcriptase. Subsequently, the specific usage of the families was analyzed by polymerase chain reaction (PCR) using combinations of the selected C beta-oligonucleotide primer and one of the family-specific V beta primers. Peripheral blood lymphocytes from four healthy volunteers and 1 "reactive" lymph node served as a control and expressed all 20 V beta families tested for. In T-cell lines, with restricted V beta expression, and in three patients with advanced MF, only one or two V beta families were expressed at the mRNA level. In an early MF lesion this monoclonal expression was absent: several V beta families were expressed with a weak intensity. This may indicate either a polyclonal origin of MF, or that too few monoclonal neoplastic cells were present in the tissue specimen. In the four nodal T-cell NHL, only one family could be clearly distinguished, whereas some of the other V beta families showed only a weak expression. These latter families represent the reactive T-cell component in the nodal T-cell NHL. Both in nodal T-cell NHL and in MF there was no preferential expression of a particular V beta family. There was a good correlation between PCR data and the expression of V beta-family protein products observed by immunohistochemistry on tissue sections of the T-cell lymphomas. All T-cell lines, three cases of MF, and three cases of nodal T-cell NHL showed a rearrangement of the TCR beta chain on DNA level.

Malignant fibrous histiocytomas in dogs and cats: an immunohistochemical study

Immunohistochemical staining was performed on seven canine and 10 feline soft tissue tumours histologically diagnosed as malignant fibrous histiocytomas (MFHs) or MFH-like tumours, and eight other histologically specified tumours (non-MFH). This was done to determine if commercially available antibodies that are used routinely in human diagnostic pathology for MFHs would express the same immunohistochemical patterns in canine and feline MFHs and MFH-like tumours. The antibodies were directed against human alpha 1-anti-trypsin (AT), human alpha 1-anti-chymotrypsin (ACT), human lysozyme, bovine S-100 protein and human desmin. AT did not show any immunoreactivity in the tissues investigated. Except for one MFH, all canine MFHs and other soft tissue tumours with a 'histiocytic' character stained for lysozyme and not for S-100. Six out of seven canine MFHs and MFH-like tumours stained positive for desmin as did most non-MFH sarcomas. Most of the canine and feline MFHs and MFH-like tumours were positive for ACT. These findings for ACT staining in canine and feline MFHs and MFH-like tumours are in agreement with the findings in human MFHs. The immunohistochemical results of canine MFHs and MFH-like tumours were different from those in cats. Feline MFHs differed from canine MFHs for both lysozyme and desmin staining.

Detection of cytomegalovirus (CMV) in granulocytes by polymerase chain reaction compared with the CMV antigen test

To compare the sensitivity and suitability of detection of active cytomegalovirus (CMV) infection by using monoclonal antibodies against CMV antigen (antigen test to detect antigenemia) and the polymerase chain reaction (PCR; to detect viral DNA) in granulocytes, 19 heart and 2 lung transplant recipients were closely monitored by these tests for at least 3 months after transplantation. All patients were CMV seropositive or had a seropositive donor. In total, 201 samples were tested; 46 were positive by both tests, 9 samples showed only antigenemia, 54 samples were positive by PCR only, and 102 samples were negative by both tests. PCR was positive earlier after transplantation in eight patients, whereas antigenemia was positive earlier after transplantation in one patient. In another four patients, both tests were positive at the same time. PCR was, on average, positive for a longer period of time. Discordant results showing a positive antigen test and a negative PCR were partly due to sampling error; some were positive by PCR on retesting. Samples which were negative by the antigen test and positive by PCR were taken at the beginning or at the end of an active CMV infection. In two patients, no active CMV infection was detected by the antigen test, cultures of urine and saliva, or serology, although PCR was positive for a long period of time in the two patients.