Expression of EGFR and follicular dendritic markers in lymphoid follicles from patients with Castleman's disease

This study investigated the useful morphologic and immunophenotypic findings for the diagnosis of Castleman's disease (CD). We focused on the distribution and expression of follicular dendritic cells (FDC) in lymphoid follicles from patients with CD. Eleven CD cases of the hyaline vascular (HV) variant and six cases of the plasma cell (PC) variant were studied using tissue microarray and paraffin resistant monoclonal antibodies CD21, CD35, and EGFR, a new novel marker of FDC, as well as an antibody against human herpes virus 8 (HHV8). Epstein-Barr virus (EBV) was detected by means of in situ hybridization with a fluorescein isothiocyanate-labeled EBV-encoded RNA (EBER) specific oligonucleotide. The FDC network of the PC variant (n=4) was similar to that seen in normal or reactive germinal centers. In contrast, all HV variants and 2 cases of the PC variant were either expanded, disrupted, or exhibited multiple tight collections of FDC both in germinal centers and in mantle zone lymphocytes. The expanded mantle zone lymphocytes were CD20+, Bcl2+, PAX5+, and MUM1- with less number of CD3+ T cells admixed. Other features of the HV variant included follicular regression and vascular ingrowth of the germinal centers, whereas features of the PC variant were follicular hyperplasia and interfollicular plasmacytosis. In addition, EBV infection was positive in three CD cases, and one case had co-expression of HHV8 and EBV infection. Taken together, we found immunophenotypic differences of mantle zone lymphocytes and FDC network patterns of lymphoid follicles in CD. Thus, we conclude that these differences are relevant for the differential diagnosis of the two histopathologic variants of CD.

Microbial induction of B and T cell areas in rabbit appendix

Gut-associated lymphoid tissue (GALT) development requires interaction with the intestinal microbiota. Because murine secondary lymphoid tissue development is driven by positive feedback interactions between B cells and stromal cells, we used in situ hybridization to determine whether intestinal commensals influence such interactions during rabbit appendix development. The features of positive feedback interactions we examined (CXCL13 mRNA expression, B cell accumulation and FDC differentiation) increased during early follicle development, but stalled in the absence of intestinal commensals. These features were reinitiated by commensals that stimulated follicle development and intrafollicular B cell proliferation. Our results suggest that rabbit appendix follicles develop in two phases: an initial phase of B cell recruitment to nascent follicles, possibly through positive feedback interactions, and a subsequent phase of intrafollicular B cell proliferation stimulated by intestinal commensals. In addition, we found that intestinal commensals stimulate appendix CCL21 mRNA expression and T cell area formation.

Intra-abdominal Follicular Dendritic Cell Sarcoma With Marked Pleomorphic Features and Aberrant Expression of Neuroendocrine Markers: Report of a Case With Immunohistochemical Analysis

Follicular dendritic cell sarcoma (FDCS) is a very rare malignant tumor arising most frequently in lymph nodes with only few reports of extranodal locations. We report the case of a 35-year-old man with a large retroperitoneal mass. Histologically the tumor was composed of highly pleomorphic cells exhibiting some uncommon features such as an epithelioid appearance, cystic spaces, and multinucleated cells with morphologic features of emperipolesis. Immunohistochemically the neoplastic cells were immunoreactive for CD21, CD23 and CD35. A previously unreported expression of neuroendocrine markers (Synaptophisyn and Neuron-Specific-Enolase) was present. Ultrastructurally no neuroendocrine secretory granules were detected. FDCS can mimic a wide variety of other malignant tumors, and a correct diagnosis requires exclusion of other neoplasms and immunohistochemical confirmation.

In vivo experimental model of human gingival mucosa using immunodeficient mice

BACKGROUND AND OBJECTIVE

To establish an in vivo experimental model for examining human periodontal tissue, the present study examined several transplant techniques that maintain the structure and characteristics of human gingival mucosa.

MATERIAL AND METHODS

Human oral mucosal tissue samples were collected from the gingiva (n = 11), palate (n = 1), and tongue (n = 3). These mucosal grafts were transplanted onto BALB/c nu/scid mice with double-mutant immunodeficiency. Murine skin, twice the size of the graft, was cut open in an ' square superset'-shape. Next, the connective tissue side of the graft was placed onto the murine connective tissue. Immunohistochemical analysis was also performed, using polyclonal rabbit antibody to involucrin, monoclonal antibody to vimentin, monoclonal antibody to CD34, and monoclonal antibody to Ki-67, to determine whether the characteristics of human oral mucosa were maintained.

RESULTS

When the connective tissue side of the graft was placed on the murine fascial membrane, the histological structure of the graft was maintained for 60 d. These grafts were examined for human characteristics using human-specific antibodies. Immunohistochemically, the expression patterns of involucrin, vimentin, and Ki-67 indicated that transplanted mucosa revealed normal human characteristics, including differentiation and proliferation up to 80 d. CD34 was not detected in the graft endothelial cells.

CONCLUSION

The present study revealed that the novel technique of transplantation of human gingival mucosa in nu/scid mice may serve as an in vivo experimental model of periodontal disease.

Standardised assessment of membrane proteinase 3 expression. Analysis in ANCA-associated vasculitis and controls

OBJECTIVES

Increased numbers of neutrophils expressing proteinase 3 on their membrane (mPR3) have been reported in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) and are suggested to be involved in AAV immunopathogenesis. In most studies, neutrophils were analysed for mPR3 expression without priming with TNFalpha, suggesting that mPR3 expression on neutrophils is dependent on other priming events, such as isolation procedures . These priming events can be variable. Therefore, we analysed mPR3 expression on neutrophils before and after priming with TNFalpha to assess whether standardised assessment of mPR3 expression requires priming. Using neutrophils before and after priming with TNFalpha, we assessed percentages of mPR3(+) neutrophils in patients with AAV and in disease and healthy controls.

METHODS

Neutrophils from patients with PR3-AAV and MPO-AAV, systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), and from healthy controls were analysed before and after priming with TNFalpha for mPR3 expression.

RESULTS

42% of all individuals analysed showed minimal expression for mPR3 on all neutrophils before priming with TNFalpha, whereas after priming a clear mPR3(+) subset was observed next to mPR3(-) neutrophils, corresponding to bimodal mPR3 expression. In patients with PR3-AAV or MPO-AAV, the percentage of mPR3(+) neutrophils after priming with TNFalpha was significantly increased (p<0.01 and p<0.05, respectively) compared with healthy controls. Percentages of mPR3(+) PMN were also increased in patients with SLE (p<0.01) but not in RA.

CONCLUSION

Standardised assessment of proteinase 3 on the membrane of neutrophils requires priming with TNFalpha. Percentages of mPR3(+) PMN are increased in AAV and SLE, but not in RA.

Follicular dendritic cell sarcoma of the spleen

Diagnosis of primary spindle cell tumors of the spleen is challenging because of the limited immunologic and cytogenetic characterization of this rare entity. We report a case of primary follicular dendritic cell (FDC) sarcoma of the spleen in a 44-year-old woman. Indications for FDC included positive staining for CD21, Ki-M4P, CD14, and fascin. Expression of both standard FDC markers CD23 and CD35 was detected immunohistochemically using tyramide signal amplification. Cytogenetic analysis revealed multiple clonal chromosomal aberrations involving unbalanced translocations of chromosomes X, 3, 5, 7, 8, 9, and 10, leading to net gains at 3q, 7p, 8q, and 9q and net losses at Xp, 8p, 9p, and 10p. Loss at Xp has been described previously in another tumor with FDC features, suggesting that this aberration might play a common role in this malignancy.

Significance of C4d deposition in the follicular lymphoma and MALT lymphoma and their relationship with follicular dendritic cells

We evaluated the deposition of C4d in follicular lymphomas (FL) and extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma). Deposition of C4d was detected in 118 lymphoma tissues from patients with lymphoma and in 20 reactive hyperplasia lymphadens (RHL) using immunohistochemistical methods. FL, MALT lymphoma, and RHL were studied using double staining for CD35/C4d and Bcl-2/C4d. We studied 26 FL tissues, 19 of which showed C4d deposition. C4d deposition was detected around the follicular dendritic cells (FDCs) in the neoplastic follicles. There was no significant difference between the positive ratio of C4d and the grades of FL. We studied 12 MALT lymphoma tissues, six of which displayed C4d deposition. In these tissues, C4d deposition was detected in the peripheral region of partially colonized follicles in the form of an irregular ring, but was not found in the central region. C4d deposition was negative in completely colonized follicles. There was no C4d deposition in diffuse large B-cell lymphomas, mantle cell lymphomas, B-small lymphocytic lymphomas, T-lymphoblastic lymphomas, peripheral T-cell lymphomas, and anaplastic large cell lymphomas. C4d around the FDCs in the neoplastic follicles was a specific indicator for FL. C4d deposition in partially colonized follicles of MALT lymphoma was completely different from that in neoplastic follicles of FL, forming a key point for differential diagnosis.

[Correlation of erythrocyte immune function between normal neonates and their mothers]

OBJECTIVE

To study the correlation of erythrocyte immune function between normal neonates and their mothers and the influence of various obstetric factors on neonatal erythrocyte immune function.

METHODS

The adherent rate of complement 3b-receptor on the surface of red blood cells (RBC-C3bRR) and the immune complex adherent rate of red blood cells (RBC-ICR) were detected using the erythrocyte saccharomyces rosette test in 104 normal neonates and their mothers. The correlation of erythrocyte immune function between neonates and their mothers was evaluated by the maternal-infant paired test.

RESULTS

The levels of RBC-C3bRR (16.80 +/- 1.56% vs 16.23 +/- 1.63%; P < 0.05) and RBC-ICR (5.72 +/- 1.63% vs 5.02 +/- 1.38%; P < 0.01) in neonates were significantly higher than those in their mothers. There was a significantly positive correlation in RBC-ICR levels between neonates and their mothers (r = 0.28, P < 0.05). No correlation was found in RBC-C3bRR levels between the two groups. Neither RBC-C3bRR nor RBC-ICR levels of neonates were associated with various obstetric factors such as amniotic fluid, placenta, umbilical cord, parturient patterns, and puerperal anemia and pregnancy-induced hypertension syndrome.

CONCLUSIONS

The erythrocyte immune function in neonates has a relatively mature level and correlates with their mothers' erythrocyte immune function. Various obstetric factors have no influences on neonatal erythrocyte immune function.

Modulation of CR1 transcript in systemic lupus erythematosus (SLE) by IFN-gamma and immune complex

Reduced expression of Erythrocyte Complement Receptor 1 (E-CR1) is envisaged to contribute significantly to the pathophysiology of systemic lupus erythematosus (SLE). We determined the levels of CR1 transcript in the neutrophils from 25 untreated patients with active SLE and 25 normal healthy individuals and, studied the effect of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and immune complexes (IC) on the same. The study revealed a marked decline in the levels of neutrophil CR1 (N-CR1) transcript in the patients with SLE, and differential pattern of IFN-gamma and IL-4 expression in the neutrophils from normals and patients. Opsonized immune complexes down regulated CR1 transcript in patients and IFN-gamma up regulated the same both in normals and patients. Immune complexes suppressed this effect of IFN-gamma. IL-4 also suppressed the effect of IFN-gamma but effect confined only to the normals. This is the first real-time RT-PCR data comparing the neutrophil CR1 expression in normals and patients with SLE and its modulation by IFN-gamma, IL-4 and immune complexes. IFN-gamma and immune complexes, respectively, emerged as the positive and negative modulators of neutrophil CR1 transcript in SLE.

Role of Dendritic Cells in Sjogren's Syndrome

Sjögren's syndrome (SS) is a chronic inflammatory and lymphoproliferative autoimmune disease of unknown aetiology. It is characterised by progressive mononuclear cell infiltration of the salivary and lacrimal glands and a decreased glandular secretion, resulting in dryness of the mouth and eyes (xerostomia and keratoconjunctivitis sicca, respectively). Dendritic cells (DC) are considered to be the most potent antigen-presenting cells. Because of their central role in initiating an immune response while maintaining tolerance, impaired function of these cells might lead to the break of peripheral tolerance and initiation of immune responses to self-antigens. This review will focus on the possible role of DC in SS.

Quantitative analysis of complement receptors, CR1 (CD35) and CR3 (CD11b), on neutrophils improves distinction between bacterial and viral infections in febrile patients: Comparison with standard clinical laboratory data

There is an ongoing need for sensitive and specific markers of bacterial infection. In this prospective study, standard clinical laboratory data (neutrophil count, serum C reactive protein level, erythrocyte sedimentation rate) and quantitative flow cytometric analysis of neutrophil complement receptors, CR1 and CR3, were obtained from 289 hospitalized febrile patients. After microbiological confirmation or clinical diagnosis, 135 patients were found to have either bacterial (n = 89) or viral (n = 46) infection. The patient data was compared to 60 healthy controls. In bacterial infections, all measured variables were significantly increased, particularly the average amounts of CR1 and CR3 on neutrophils were over three-fold and two-fold higher, respectively, compared to viral infections and controls. We described a novel marker of local and systemic bacterial infections designated 'clinical infection score (CIS) point', which incorporates quantitative analysis of complement receptors on neutrophils and standard clinical laboratory data. CIS point varied between 0 and 8, and displayed 98% sensitivity and 97% specificity in distinguishing between bacterial and viral infections [average (S.D.); CIS points: 6.2 (1.7) vs. 0.6 (1.0); p < 0.001]. These findings suggest that the proposed CIS-based diagnostic test could potentially assist physicians in deciding whether antibiotic treatment is necessary.

Bone marrow angiogenesis in aplastic anemia

The objective of this study was to investigate the status of bone marrow angiogenesis in aplastic anemia (AA). Bone marrow specimens from 32 patients with AA and 16 normal controls were studied. The number of bone marrow microvessels was examined by means of immunohistochemical staining for CD34. Determination of microvessel density (MVD) and angiogenesis grading were done in a blinded manner. The results showed that the bone marrow MVD in patients with AA was significantly lower than that in healthy subjects (P < 0.01). MVD in patients with severe and moderate AA was lower than that in control group, respectively (P < 0. 01). There is significant MVD difference between severe AA and moderate AA (P < 0.05). Angiogenesis grade and MVD in AA were positively correlated (r = 0.64, P < 0.01). It is concluded that bone marrow angiogenesis in AA patients is lower than that in normal controls. Defect of angiogenesis in bone marrow may play a role resulting in or aggravating hematopoietic aplasia in patients with AA.

Follicular dendritic-like cells derived from human monocytes

BACKGROUND

Follicular dendritic cells (FDCs) play a central role in controlling B-cell response maturation, isotype switching and the maintenance of B-cell memory. These functions are based on prolonged preservation of antigen and its presentation in its native form by FDCs. However, when entrapping entire pathogens, FDCs can turn into dangerous long-term reservoirs that may preserve viruses or prions in highly infectious form. Despite various efforts, the ontogeny of FDCs has remained elusive. They have been proposed to derive either from bone marrow stromal cells, myeloid cells or local mesenchymal precursors. Still, differentiating FDCs from their precursors in vitro may allow addressing many unsolved issues associated with the (patho-) biology of these important antigen-presenting cells. The aim of our study was to demonstrate that FDC-like cells can be deduced from monocytes, and to develop a protocol in order to quantitatively generate them in vitro.

RESULTS

Employing highly purified human monocytes as a starter population, low concentrations of Il-4 (25 U/ml) and GM-CSF (3 U/ml) in combination with Dexamethasone (Dex) (0.5 microM) in serum-free medium trigger the differentiation into FDC-like cells. After transient de-novo membrane expression of alkaline phosphatase (AP), such cells highly up-regulate surface expression of complement receptor I (CD35). Co-expression of CD68 confirms the monocytic origin of both, APpos and CD35pos cells. The common leukocyte antigen CD45 is strongly down-regulated. Successive stimulation with TNF-alpha up-regulates adhesion molecules ICAM-1 (CD54) and VCAM (CD106). Importantly, both, APpos as well as APneg FDC-like cells, heterotypically cluster with and emperipolese B cells and exhibit the FDC characteristic ability to entrap functionally preserved antigen for prolonged times. Identical characteristics are found in monocytes which were highly expanded in vitro by higher doses of GM-CSF (25 U/ml) in the absence of Dex and Il-4 before employing the above differentiation cocktail.

CONCLUSION

In this work we provide evidence that FDC-like cells can be derived from monocytes in vitro. Monocyte-derived FDC-like cells quantitatively produced offer a broad utility covering basic research as well as clinical application.

IgG and complement receptor expression in children treated by peritoneal dialysis

Children treated by peritoneal dialysis (PD) are at increased risk of infections. IgG receptors (FcgammaRs) and complement receptors (CRs) on white blood cells (WBCs) are important for the phagocytic process. We have investigated FcgammaR and CR expression on monocytes, macrophages and neutrophils in blood and in peritoneal dialysis effluent (PDE) of 39 PD children. WBCs were isolated from blood and PDE, labelled with FITC-conjugated CD16 (FcgammaRIII), CD32 (FcgammaRII), CD64 (FcgammaRI), CD11b (CR3) and CD35 (CR1) monoclonal antibodies, and analysed by flow cytometry. Peritoneal cells had lower percentages of FcgammaR-positive or CR-positive cells than blood. On the other hand, the receptor number per cell [mean fluorescence intensity (MFI)] was higher on peritoneal macrophages and neutrophils than blood, except for CD16. The FcgammaR and CR expression in blood and dialysate did not change significantly during the first year of PD treatment. During a peritonitis episode the MFI of all receptors in blood increased only on monocytes, with the exception of CD32. The percentages of FcgammaR-positive and CR-positive macrophages and neutrophils in the PDE increased, whereas the MFI did not increase consistently. Peritoneal cells of PD children showed a lower percentage of FcgammaR-positive and CR-positive neutrophils and macrophages, combined with an increased MFI, indicating a state of activation. Blood and peritoneal cells are capable of up-regulating the receptor expression during peritonitis but probably not to a maximum level.

Follicular dendritic cell sarcoma of the pharyngeal region: Histologic, cytologic, immunohistochemical, and ultrastructural study of three cases

Follicular dendritic cell sarcoma is a tumor of recent description and characterization; it is often underdiagnosed because it is easily confused with other entities. Three cases of follicular dendritic cell sarcoma are described in the present article. The first occurred in the parapharyngeal space in a 29-year-old woman who developed multiple recurrences over the span of 10 years. The second was located in the left tonsil in a 48-year-old man, and the third case developed in the parapharyngeal space in a 26-year-old man. All cases were positive for CD21 and CD35 and ultrastructurally they displayed a morphologic spectrum. The first case featured spindle cells with interdigitated long cell processes joined by well-developed desmosomes. In the other two cases there were round to ovoid cells with interwoven processes connected by occasional desmosomes. Including these three cases, a total of 20 follicular dendritic cell sarcoma of the pharyngeal region have been reported to date. The clinical behavior of these tumors is similar to other low-grade sarcomas.

Analysis of the optimal blood sampling conditions for estimation of hematopoietic progenitor cell count by the SE-9000 automated hematolyzer

We evaluated the optimal conditions for blood sampling for hematopoietic progenitor cells (HPCs) as estimated by the immature information program of the SE-9000 automated hematology analyzer. The HPC count was most stable when the blood samples were incubated at room temperature with ethylene-diaminetetraacetic acid dipotassium (EDTA-2K) as an anticoagulant. The HPC count should, however, be measured within 4 h after blood collection, even under optimal conditions. In contrast, the CD34+ cell count estimated by flow cytometric analysis was stable for at least 21 h after the blood samples were incubated with EDTA-2K at room temperature or 4 degrees C. When appropriate blood samples were used, the HPC count in the peripheral blood significantly correlated with the CD34+ cell count in the peripheral blood and in the apheresis yields (r = 0.798 and 0.635, respectively); therefore, the HPC count is a reliable predictor for initiation of apheresis procedures to obtain sufficient HPCs for peripheral blood stem cell transplantation.

Modulation of urinary CR1 in systemic lupus erythematosus

The decline in the levels of erythrocyte complement receptor 1 (ECR1) in systemic lupus erythematosus (SLE) has been widely reported. The most probable cause for this decline is excessive proteolytic shedding of CR1 from the cell surface. Similarly a decline in glomerular CR1 (GCR1) has also been reported in SLE. Because CR1 is excreted in urine it is imperative to study the relationship of urinary CR1 (uCR1) with ECR1 and GCR1, and their overall correlation with disease activity. We have determined the levels of uCR1, ECR1 and GCR1 in SLE patients and compared them with normal controls and minimal change disease (MCD) patients. We found a significant decline in both uCR1 and GCR1 in SLE but not in MCD; levels of uCR1 in MCD were either comparable to those of controls or higher. Immunofluorescence for GCR1 was very high in MCD. We did not find any correlation between ECR1, uCR1 and kidney function tests on divariate scatter analyses. The correlation coefficient for uCR1 and GCR1 was highly significant and positive. Our findings thus suggest that uCR1 reflects the levels of GCR1 expression, which decline drastically in SLE. Therefore we envisage uCR1 as a potential marker for glomerular involvement in SLE.

Effect of lead exposure on the immune function of lymphocytes and erythrocytes in preschool children

OBJECTIVE

To investigate the influence of lead exposure on the immune function of lymphocytes and erythrocytes in preschool children.

MATERIALS AND METHODS

A group of 217 children three to six years of age from a rural area were given a thorough physical examination and the concentration of lead in blood samples taken from each subject was determined. The indices of lymphocyte immunity (CD+3CD+4, CD+3CD+8, CD+4CD+8, CD-3CD+19) and erythrocyte immunity (RBC-C3b, RBC-IC, RFER, RFIR, CD35 and its average fluorescence intensity) of 40 children with blood lead levels above 0.483 micromol/L were measured and compared with a control group.

RESULTS

The blood lead levels of the 217 children ranged from 0.11 micromol/L to 2.11 micromol/L. The CD+3CD+4 and CD+4CD+8 cells were lower (P<0.01) and the CD+3CD+8 cells were higher in the lead-poisoned subjects than those in the control group (P<0.05). CD+3 and CD-3CD+19 did not show significant differences. Although the RBC-C3b rosette forming rate was lower and the RBC-IC rosette forming rate was higher in the lead-poisoned group, this difference could not be shown to be statistically significant (P>0.05). RFIR was found to be lower in the lead-poisoned group (P<0.01). Compared with the control group, the positive rate of CD35 was not found to be significantly different in a group of 25 lead-poisoned children (P>0.05), while the average fluorescence intensity was lower in the lead-poisoned group (P<0.05).

CONCLUSION

Lead exposure can result in impaired immune function of T lymphocytes and erythrocytes in preschool children.

Association of complement receptor 1 (CR1, CD35, C3b/C4b receptor) density polymorphism with glomerulonephritis in Indian subjects

Complement receptor 1 (CR1, CD35, C3b/C4b receptor), a polymorphic membrane bound glycoprotein is important both as a complement regulatory protein, and as a vehicle for immune complex clearance. It is differentially expressed on erythrocytes, eosinophils, monocytes, B and T-lymphocytes, dendritic cells and kidney podocytes. It also occurs in the plasma as soluble CR1 (sCR1) and in urine as urinary CR1 (uCR1). Different population studies have either suggested or refuted the functional and physiological significance of genomic (HH, high erythrocyte CR1 expression; HL, intermediate and LL, low expression) polymorphism of CR1 in health and disease. Prevalence of autoimmune disorders like RA, GN and SLE is higher in Asian-Indians compared to the western world. Although several studies from India emphasize the modulation of E-CR1 levels as a key factor in the pathophysiology of glomerulonephritis (GN), none of them, however, provide much information on the role of CR1 gene variance in this context. We, therefore, carried out the study of CR1 polymorphism in 117 normal Indian subjects and 65 patients suffering from glomerulonephritis in order to study its possible association with the disease and E-CR1 levels. This is the first study of its kind in the Indian population, in which, the direct effect of a particular genotype on the E-CR1 levels and its possible association with the disease has been studied simultaneously.

Altered regulation of Fc gamma RII on aged follicular dendritic cells correlates with immunoreceptor tyrosine-based inhibition motif signaling in B cells and reduced germinal center formation

Aging is associated with reduced trapping of Ag in the form of in immune complexes (ICs) by follicular dendritic cells (FDCs). We postulated that this defect was due to altered regulation of IC trapping receptors. The level of FDC-M1, complement receptors 1 and 2, FcgammaRII, and FDC-M2 on FDCs was immunohistochemically quantitated in draining lymph nodes of actively immunized mice for 10 days after Ag challenge. Initially, FDC FcgammaRII levels were similar but by day 3 a drastic reduction in FDC-FcgammaRII expression was apparent in old mice. FDC-M2 labeling, reflecting IC trapping, was also reduced and correlated with a dramatic reduction in germinal center (GC) B cells as indicated by reduced GC size and number. Nevertheless, labeling of FDC reticula with FDC-M1 and anti-complement receptors 1 and 2 was preserved, indicating that FDCs were present. FDCs in active GCs normally express high levels of FcRs that are thought to bind Fc portions of Abs in ICs and minimize their binding to FcRs on B cells. Thus, cross-linking of B cell receptor and FcR via IC is minimized, thereby reducing signaling via the immunoreceptor tyrosine-based inhibition motif. Old FDCs taken at day 3, when they lack FcgammaRII, were incapable of preventing immunoreceptor tyrosine-based inhibition motif signaling in wild-type B cells but old FDCs stimulated B cells from FcgammaRIIB(-/-) mice to produce near normal levels of specific Ab. The present data support the concept that FcR are regulated abnormally on old FDCs. This abnormality correlates with a reduced IC retention and with a reduced capacity of FDCs to present ICs in a way that will activate GC B cells.

Effect of HIV-1 antiretroviral drugs on cytoadherence and phagocytic clearance of Plasmodium falciparum-parasitised erythrocytes

In response to the HIV/AIDS pandemic, antiretroviral treatment is currently being implemented in sub-Saharan Africa, where malaria and HIV-1 co-infections are highly prevalent. The effectiveness and tolerability of antiretrovirals in patients with malaria and HIV-1 co-infection have not been investigated. Antiretrovirals decrease CD36 surface concentrations in vivo, which might impair receptor function and affect parasite-host interactions. Thus, we investigated the effects of these drugs on CD36-mediated cytoadherence and non-opsonic phagocytosis of Plasmodium falciparum parasitised erythrocytes in vitro. The protease-inhibitor class of antiretrovirals particularly impairs CD36-mediated cytoadherence and non-opsonic phagocytosis of parasitised erythrocytes by human macrophages. Such treatment might therefore contribute to altered malaria disease outcomes in co-infected patients.

[Clinical and hematological aspects of follicular lymphoma]

A comprehensive clinical-and-laboratory examination of patients with non-Hodgkin's malignant lymphomas revealed a lack of correspondence between results of histological and immunophenotypical investigations. The most characteristic feature appeared to be the presence of CD10, CD11a, and CD35 antigens. Absence of CD95 antigen on tumour cells is regarded as an unfavourable prognostic sign in patients with follicular lymphomas as is presence of CD10 antigen on the above cells.

Follicular dendritic cell tumor in the oro-pharyngeal region: report of a case and a review of the literature

A case of follicular dendritic cell tumor (FDC tumor) arised in the aro-pharyngeal region is reported in a 16-year-old Japanese boy. He had a swelling in the right retromolar trigone and soft palate. Clinical examination disclosed a 25 mm x 30 mm, elastic hard, ulcerated mass. CT scans showed a low density lesion in the right medial parapharyngeal area. The biopsy specimen revealed a low-grade malignant tumor. The patient underwent a tumorectomy which was extended to include the adjacent palatine tonsil. The tumor cells, with a clear cytoplasm and oval nucleus, were immunoreactive for S-100 (N/A), CD 21 (1F8), fascin (55K-2) and FDC (CNA42). The fascicular sheet pattern arrangement of the tumor cells was partly characteristic. The final diagnosis was an follicular dendritic cell tumor. Three courses of adjuvant chemoradiotherapy were administered postoperatively. Clinical features, pathological diagnosis and immunohistochemical markers for distinguishing FDC tumor are reviewed.

Endothelial cells modulate eosinophil surface markers and mediator release

Migration from blood to tissue modulates eosinophil function, possibly through interactions with endothelial cells. The effects of contact with and migration through endothelial cells on eosinophil expression of surface markers and release of leukotriene C4 were evaluated. A small proportion (2.6%) of eosinophils spontaneously migrated through endothelial cell monolayers. Activation of endothelial cells by interleukin (IL)-4 or IL-1beta slightly increased this migration (to 12.4%), which became much greater when a chemoattractant was placed in the lower chamber (84.3%). However, the chemotactic effect was downregulated by pretreating endothelial cells with interferon gamma (IFN-gamma; 63.1%). At baseline, 5% of eosinophils expressed CD69; this increased to 30.7% in culture on untreated endothelial cells and to 50.9% on IL-1beta-pretreated endothelial cells. This effect was mediated through intercellular adhesion molecule-1/CD11b interaction. Eosinophil migration through endothelial cells further increased CD69 expression to 63.9% and also increased CD35 expression from 83.3 to 91.3%. Upon stimulation, eosinophils that had migrated through endothelial cells produced more leukotriene C4 than control cells (872.4 and 103.9 pg x mL(-1), respectively). Endothelial cell pretreatment with IL-4 or IL-1beta further increased leukotriene C4 release (1,789.1 and 2,895.1 pg x mL(-1), respectively), whereas pretreatment with IFN-gamma decreased it (293.7 pg x mL(-1)). These data show that in vitro interactions with endothelial cells upregulate eosinophil membrane receptor expression and mediator release and that these effects are differently modulated by T-helper cell type 1 and 2 cytokines. These eosinophil modulations may play an important role in asthma pathogenesis.

Human cord blood CD34+Pax-5+ B-cell progenitors: single-cell analyses of their gene expression profiles

Circulating CD34(+) cells are used in reparative medicine as a stem cell source, but they contain cells already committed to different lineages. Many think that B-cell progenitors (BCPs) are confined to bone marrow (BM) niches until they differentiate into B cells and that they do not circulate in blood. The prevailing convention is that BCP transit a CD34(+)CD19(-)10(+) early-B-->CD34(+)CD19(+)CD10(+) B-cell progenitor (pro-B)-->CD34(-)CD19(+)CD10(+) B-cell precursor (pre-B) differentiation pathway within BM. However, populations of CD34(+)CD10(+) and CD34(+)CD19(+) cells circulate in adult peripheral blood and neonatal umbilical cord blood (CB) that are operationally taken as BCPs on the basis of their phenotypes, although they have not been submitted to a systematic characterization of their gene expression profiles. Here, conventional CD34(+)CD19(+)CD10(+) and novel CD34(+)CD19(+)CD10(-) BCP populations are characterized in CB by single-cell sorting and multiplex analyses of gene expression patterns. Circulating BCP are Pax-5(+) cells that span the early-B, pro-B, and pre-B developmental stages, defined by the profiles of rearranged V-D-J(H), CD79, VpreB, recombination activating gene (RAG), and terminal deoxynucleotidyl transferase (TdT) expression. Contrary to the expectation, circulating CD34(+)CD19(-)CD10(+) cells are essentially devoid of Pax-5(+) BCP. Interestingly, the novel CD34(+)CD19(+)CD10(-) BCP appears to be the normal counterpart of circulating preleukemic BCPs that undergo chromosomal translocations in utero months or years before their promotion into infant acute lymphoblastic B-cell leukemia after secondary postnatal mutations. The results underscore the power of single-cell analyses to characterize the gene expression profiles in a minor population of rare cells, which has broad implications in biomedicine.

Expression of the vascular endothelial growth factor (VEGF) family in human endometrial blood vessels

Endometrial regrowth is associated with intense angiogenesis, for which vascular endothelial growth factor-A (VEGF-A) is an important regulator. However, the expression of other members of the VEGF family is less well documented. The aim of this study was to localize members of the VEGF family (VEGF-A, -B and -C), and their receptors (VEGFR1, 2 and 3) in human endometrial blood vessels. Endometrial biopsies collected from four healthy and fertile women were used for immunohistochemistry assessments. Co-localization of VEGF-family proteins with CD34 stained endothelial structures was determined by image analysis. We demonstrate here the marked expression of VEGF-A as well as VEGFR2 and 3 in capillaries. Arterioles expressed VEGF-B, VEGFR1, 2, and 3 moderately and VEGF-A variably. Venules expressed only VEGFR3 markedly. In contrast, VEGF-C was not expressed in the arterioles, but moderately in the capillaries and weakly in the venules. VEGF-B was expressed in all blood vessels; however, VEGF-B was weakly expressed in capillaries and arterioles and moderately expressed in venules and arterioles. Thus, expression of VEGF-A. B and C and VEGF receptors 1-3 in endometrial blood vessels indicates a highly structured involvement of VEGF in the regulation of angiogenesis in the human endometrium.

Overexpression of complement receptors and related antigens on the surface of bone marrow mast cells in patients with systemic mastocytosis

Depending on their stage of maturation and other factors, mast cell (MC) subsets differ from each other in terms of the expression of complement-associated antigens. This study analysed the expression of various complement-related cell surface antigens (CD11b/CR3, CD11c/CR4, CD35/CR1, CD55/DAF, CD59/MIRL, CD88/C5aR) on bone marrow mast cells (BMMC) in patients suffering from systemic mastocytosis (SM), other haematological diseases and non-haematological disorders (control groups). Expression of complement-associated cell surface antigens was analysed by flow cytometry. There were clear immunophenotypic differences between BMMC obtained from patients with SM and those from the control subjects: the percentage of patients expressing surface CD11c, CD35 and CD88 was significantly higher in patients with SM (76%, 100%, 54%) than in the control subjects (58%, 11%, 18%) (P < 0.05). In addition, the levels of CD11c, CD35 and CD88 expressed per MC (sites per cell) were significantly higher (P < 0.05) in SM than in the control group. Expression of the complement regulatory molecules CD55 and CD59 was detected in BMMC in all patients analysed. However, the levels of CD59 per BMMC were higher in patients with SM as compared with the control subjects, which could help to explain the formation of BMMC aggregates in the former group of individuals. Together, our results showed that BMMC in systemic mastocytosis overexpressed the cell surface membrane receptors involved in binding of complement components and complement-mediated cell activation. Whether this pathological expression of complement receptors is of pathophysiological significance remains to be determined.

Defective Fc-, CR1- and CR3-mediated monocyte phagocytosis and chemotaxis in common variable immunodeficiency and X-linked agammaglobulinemia patients

Blood monocyte phagocytic functions were evaluated by chemotaxis, phagocytosis, and superoxide anion production in nine patients with common variable immunodeficiency (CVI), eight patients with X-linked agammaglobulinemia (XLA), and in 17 normal subjects. Further laboratory diagnosis included the determination of the Bruton's tyrosine kinase (Btk) protein expression in monocytes using flow cytometry. The analysis of monocyte phagocytic function demonstrated that CR3-, CR1-, and Fc-mediated phagocytosis (p = 0.0001) were significantly decreased in CVI and XLA patients, and chemotaxis of monocytes (p = 0.0082) was reduced in XLA patients. Superoxide anion production, however, did not differ between the CVI, XLA, and the control groups. The cytoplasmic expression of Btk protein in monocytes was normal in CVI patients and decreased or not detected in XLA patients. It is proposed that impaired chemotaxis and phagocytosis by monocytes may be a characteristic of the innate immune system in CVI and XLA patients, providing a new direction for the physiopathology of these immunodeficiencies.

Essential role for the C5a receptor in regulating the effector phase of synovial infiltration and joint destruction in experimental arthritis

A characteristic feature of rheumatoid arthritis is the abundance of inflammatory cells in the diseased joint. Two major components of this infiltrate are neutrophils in the synovial fluid and macrophages in the synovial tissue. These cells produce cytokines including tumor necrosis factor alpha and other proinflammatory mediators that likely drive the disease through its effector phases. To investigate what mechanisms underlie the recruitment of these cells into the synovial fluid and tissue, we performed expression analyses of chemoattractant receptors in a related family that includes the anaphylatoxin receptors and the formyl-MetLeuPhe receptor. We then examined the effect of targeted disruption of two abundantly expressed chemoattractant receptors, the receptors for C3a and C5a, on arthritogenesis in a mouse model of disease. We report that genetic ablation of C5a receptor expression completely protects mice from arthritis.

[Dermatofibrosarcoma protuberans of the breast: a case report]

We describe a dermatofibrosarcoma protuberans (DFSP) of the breast and briefly report about such cases previously mentioned in the literature. A 27-year-old woman was referred because of the progressive increase, during pregnancy, of a mammary nodule located between the internal quadrants of the right breast. Its clinical and radiologic features suggested a fibroadenoma. Lumpectomy revealed a 3-cm, gray-whitish, fasciculated nodule. Histological examination showed a neoplasm characterized by a highly and monomorphic cellular proliferation of spindle-shaped cells, arranged in bundles displaying repetitive storiform growth pattern and infiltrating the adjacent mammary tissue. Lack of necrosis and low mitotic rate was observed. At immunohistochemistry the tumor cells were diffusely positive for vimentin and CD34, but negatively stained with CD99, bc-2, desmin, smooth-muscle actin, S100 protein and cytokeratins. A diagnosis of mammary dermatofibrosarcoma protuberans (DF-SP) was posed. Neoplastic involvement of surgical margins led to a subsequent quadrantectomy without regional lymphadenectomy. The patient was alive and disease-free at the 8-month follow-up. Mammary DFSP is rare. Its preoperative diagnosis is extremely difficult, particularly when radiologic images show an intraparenchymal lesion with round borders. We report such a case and briefly review the pertinent literature. Morphologic parameters to distinguish DFSP from other spindle cell lesions of the breast are discussed.

Circulating highly fluorescent reticulocytes to predict the adequate harvesting of peripheral blood progenitor cells in platinum-based chemotherapy

We prospectively evaluated whether peripheral blood progenitor cells (PBPC) yield from a single leukapheresis could be predicted by measurement of circulating highly fluorescent reticulocytes (HFR). PBPC were collected from 46 leukaphereses in 15 patients with gynecological cancer following platinum-based chemotherapy. Once a level of at least 5.0% HFR was achieved, sufficient PBPC were collected in a single harvest in 71% of the procedures. Whereas, failure to mobilize sufficient PBPC occurred in 24 of 28 leukaphereses when the percentage of circulating HFR was less than 5.0%. In conclusion, circulating HFR may aid in the efficiency of PBPC collections in platinum-based chemotherapy.

Manipulation of lymphoid microenvironments in nonhuman primates by an inhibitor of the lymphotoxin pathway

Reticular networks in lymphoid organs play critical roles in the organization of local microenvironments. A number of these elements are maintained by continual signaling through the lymphotoxin system. Evaluation of the lymphotoxin (LT) pathway in primates using a fusion protein decoy provides a unique opportunity to assess modulation of splenic microenvironments in a species with considerably greater background immunological activity compared with rodents. Within the germinal center microenvironment, treatment resulted in a collapse of follicular dendritic cell (FDC) networks and in the disappearance of a ringlike network of immune complex-carrying cells, although some other attributes of the germinal center appeared to be unaltered. Treatment also resulted in changes in the splenic marginal zone, a microenvironment where the architecture is notably different from that of the rodent. Cessation of treatment and recovery allowed us to monitor reemergence of these cell types and revealed that FDCs rely on LT-dependent signals to recompact into appropriately positioned tight networks. Despite the loss of FDC networks, the primary Ab response to keyhole limpet hemocyanin was unaltered over a 20-day period. Manipulation of these microenvironments may represent a novel approach to modulating immune function in human disease.

The mechanism of loss of CR1 during maturation of erythrocytes is different between factor I deficient patients and healthy donors

During the in vivo maturation of erythrocytes, the number of CR1 per cell decreases by approximately two-thirds in 30 days. The CR1 loss is enhanced in several diseases such as SLE, AIDS, and particularly in factor I deficiency. Microvesicles enriched in CR1 and DAF are released from erythrocytes matured in vitro, leading to the same loss of both molecules. When comparing reticulocytes and erythrocytes, CR1 and DAF were lost similarly in 15 normal individuals, suggesting that vesiculation may be at the origin of CR1 loss in vivo. However, the enhanced loss of CR1 in 3 patients with factor I deficiency was contrasted with a normal loss of DAF, raising the possibility that, in this pathological condition, CR1 might be proteolytically cleaved, leaving small CR1 fragments on the erythrocytes. To answer this question, a rabbit polyclonal antibody was raised against the cytoplasmic (tail) domain of CR1, which recognised specifically CR1 of erythrocytes and urinary vesicles on Western blots. However, no CR1 fragments could be detected on erythrocytes of the factor I deficient patients although this antibody was able to recognise CR1 fragments after treatment of normal erythrocytes or urinary vesicles with elastase. These data suggest that cell surface domains rich in CR1, but not in DAF, are specifically lost in factor I deficiency.

Phagocytosis by emigrated, intra-abdominal neutrophils is depressed during human secondary peritonitis

The phagocytic function of neutrophils is a crucial element in host defense against invading microorganisms. Patients with diffuse peritonitis depend on adequate reactivity of neutrophils, in particular locally in the peritoneal cavity as well as in the circulation. This study examined phagocytosis as well as numerical expression of Fcgamma I-III (CD16, CD32, CD64) and complement receptors (CD18, CD35) of emigrated, intra-abdominal and circulating neutrophils during human secondary peritonitis using fluorescence-activated cell analysis. Optimally opsonized E. coli bacteria were used independently of the well-known low level of opsonic molecules during peritonitis. Compared with controls (abdominal surgery without peritonitis), the percentage of emigrated neutrophils which engulfed E. coli bacteria was significantly depressed until 48 h after diagnosis of, and surgery for, peritonitis. When patients with complicated peritonitis (septic shock, multiple organ failure) were compared with patients without complications, phagocytosis was even more depressed in patients with complications. Numerical expression of CD64 (Fcgamma RI) and CD35 (CR1) increased significantly on emigrated polymorphonuclear leukocytes (PMNs) during peritonitis when compared to controls. There was no difference in CD18 and CD32 (Fcgamma RII) expression between the two groups. Numerical expression of CD16 (Fcgamma RIII) on emigrated PMNs decreased significantly in peritonitis. This was more pronounced in patients with complicated peritonitis. We conclude that there is a long-lasting depression of phagocytosis by emigrated PMNs during peritonitis, independent of the opsonic activity. Our data suggest that decreased phagocytosis might be correlated to the profound drop in CD16 on these cells.

Phenotype of fetal monocytes and B lymphocytes during the third trimester of pregnancy

The neonate typically exhibits an immature immune response compared with the adult, yet the fetus is able to generate antigen-specific responses from around 20-22 weeks of gestation. Although antigen-presenting cells (APCs) must have attained the necessary level of maturity to support this, very little is known about the phenotype and function of these populations during human fetal development. Whole blood flow cytometry was, therefore, utilised to phenotype fetal/neonatal circulating monocytes and B cells throughout the third trimester of pregnancy. The percentage of B cells (CD19+) expressing MHC Class II was comparable to the adult at all gestations, whereas the percentage of MHC Class II-positive monocytes (CD14+) increased significantly over gestation (P=0.0008) but remained lower than the adult at term. In contrast, the percentage of CD40+ or CD86+ fetal/neonatal monocytes at all gestations was comparable to the adult, but there was a maturational increase in the percentage of CD40+ or CD86+ B cells (P=0.007) to adult levels by term. The expression of CD14 itself (mean fluorescence intensity, MFI) showed a trend to increase over gestation (P=0.062) and, although all CD14+ cells expressed other receptors associated with innate immune responses (CD11b and CD35), there was fluctuation in the intensity of expression over gestation. Functional immaturity of neonatal antigen-specific immune responses could be associated with reduced co-stimulation provided by both monocytes (via reduced MHC Class II) and B cells (via reduced CD40 and CD86); altered innate responsiveness of monocytes could also contribute.

In vitro RBC exposure to Plasmodium falciparum has no effect on RBC antigen expression

Severe malarial anaemia is a leading cause of death in African children younger than 3 years of age who are infected with Plasmodium falciparum. The pathogenesis of this anaemia is not understood. The purpose of this study was to determine if P. falciparum induces changes in RBC membranes that contribute to the immune destruction of RBCs. RBCs were collected from healthy subjects and tested using standard haemagglutination assays for 45 antigens representing 21 blood group systems/collections before and after exposure to P. falciparum, strain FVO. Lectins were used to determine whether crypt or neoantigens were expressed on the RBC membrane. Polybrene was used to detect changes in sialic acid. RBCs were cultured in vitro with and without the parasite, and blinded serologic studies were completed. CD35 (complement receptor 1), CD55 (decay-accelerating factor), CD59 (membrane inhibitor of reactive lysis) and CD47 (integrin-associated protein) flow cytometric assays were compared for infected and uninfected RBCs. The percentage of parasitaemia was determined using Giemsa-stained thin blood films. Two (Ch, Lub) of the 45 antigens had differing strengths of agglutination between infected and uninfected RBCs, but these differences were resolved with a second source of antisera. Forty-three antigens showed no significant differences in the strength of agglutination between the infected and uninfected RBCs. Lectin and polybrene testing showed no differences. CD35, CD55, CD59 and CD47 levels showed no significant differences. P. falciparum does not appear to alter the expression of classified immunogenic antigens on the RBC membrane in this in vitro system. The pathogenesis of the haemolytic episode that occurs in these children remains unclear.

Defective Fc-dependent processing of immune complexes in patients with systemic lupus erythematosus

OBJECTIVE

To explore the Fc receptor-dependent handling of immune complexes (ICs) by the fixed mononuclear phagocytic systems (MPS) in patients with systemic lupus erythematosus (SLE).

METHODS

The processing in vivo of soluble model (123)I-hepatitis B/ anti-hepatitis B ICs was studied in 12 healthy subjects and 10 patients with active SLE. ICs that fixed complement poorly were prepared specifically in order to explore Fc receptor-dependent clearance mechanisms. Clearance kinetics and organ uptake were assessed by computer-aided gamma scintigraphy and serial blood sampling.

RESULTS

In both patients and controls, the main site of IC clearance was the liver; only 2-6% of injected ICs were taken up in the spleen. The kinetics of initial IC clearance were similar in both groups, but defective hepatic retention of ICs was demonstrated in patients with SLE. At 1 hour, hepatic activity in patients had fallen to 56% of maximum, compared with 74% in controls (P = 0.0002). Precipitation studies performed on serum samples using staphylococcal protein A-Sepharose indicated that antibody-complexed tracer was released from the liver 20-50 minutes after injection.

CONCLUSION

These results indicate that Fc-mediated clearance of ICs is defective in patients with SLE and suggest that ligation of ICs by Fc receptors is critical for their efficient binding and retention by the fixed MPS in the liver.

Extranodal follicular dendritic cell sarcoma of the head and neck region: three new cases, with a review of the literature

Extranodal follicular dendritic cell (FDC) sarcoma of the head and neck region is uncommon, with 16 well-documented cases previously reported (four in the tonsil, four in the pharynx, two in the palate, five in the soft tissue, and one in the thyroid). We here report an additional three cases of extranodal FDC sarcoma in the tonsil (two cases) and pharynx (one case). In these new cases, the neoplastic cells were arranged in diffuse, fascicular, and vaguely whorled growth patterns. A background lymphocytic infiltrate was sprinkled throughout the neoplasms, with focal prominent perivascular cuffing. Scattered multinucleated giant cells were present. Immunohistochemically, tumor cells were strongly and diffusely positive for follicular dendritic cell markers CD21 and CD35. Tumor cells were diffusely positive for fascin and negative for leukocyte common antigen, S-100 protein, cytokeratin, and Epstein-Barr virus (EBV) latent membrane protein-1 (EBV-LMP). EBV was also not detected in the tumor cells by in situ hybridization for EBV-encoded RNAs. FDC sarcomas are probably an underrecognized neoplasm, especially when they occur in extranodal sites in the head and neck region. Two of the three new cases we report were initially misdiagnosed, and five cases of extranodal FDC sarcoma in the head and neck region reported in the recent literature were initially misdiagnosed. Our aim is to complement the current understanding of this neoplasm and alert pathologists to this rare entity in this region to avoid misdiagnosis. Recognition of extranodal FDC sarcoma requires a high index of suspicion, but this tumor has numerous distinctive histological features that should bring the neoplasm into the differential diagnosis. Confirmatory immunohistochemical staining with follicular dendritic cell markers such as CD21 and/or CD35 is essential for the diagnosis. Correct characterization of this neoplasm is imperative given its potential for recurrence and metastasis.

Follicular dendritic cell tumor of the mediastinum

Follicular dendritic cell tumor (FDT) is a rare neoplasm usually occurring in the laterocervical lymph nodes, but presentations elsewhere are also well documented. We report a case of FDT in a 48-year-old man with myasthenia gravis, in whom a slow-growing mediastinal mass that had been surgically excised manifested after 3 years with a local recurrence in the same site. The lesion was aspirated and cytology showed a tumor composed of groups of oval or elongated cells intermingled with several mature small lymphocytes. On histology, the tumor was highly cellular with abundant perivascular lymphocytic infiltration; large cells with pale, eosinophilic cytoplasm and round nuclei, arranged in fascicles often showed a storiform pattern. Occasional binucleated cells were also present. A panel of antibodies showed positivity only for CD21 and CD35, and a weak response to S-100. Electron microscopy showed that the layer cells had convoluted nuclei and elongated interdigitating processes with desmosome-like junctions. The definitive diagnosis of FDT can be concluded only with positive immunostaining for CD21 and CD35. However, in the presence of a mixed population of lymphocytes and larger eosinophilic cells the hypothesis of FDT should always be considered.

Intraabdominal follicular dendritic cell sarcoma: report of a case with fine needle aspiration findings

BACKGROUND

Follicular dendritic cell sarcoma is a rare tumor derived from dendritic cells of lymphoid follicles. Although it shows characteristic cytologic, histologic and immunohistochemical features, it may be misdiagnosed because of the lack of experience with this entity. There are few reports in the cytologic literature describing this entity.

CASE

A left hypochondrial mass was found in an 80-year-old man who had a past history of colonic carcinoma. A computed tomography-guided fine needle aspiration biopsy was performed, and the findings were initially thought to be compatible with metastatic carcinoma. The mass was excised, and a diagnosis of follicular dendritic cell sarcoma was made.

CONCLUSION

Follicular dendritic cell sarcoma is characterized by loosely cohesive or syncytial groups of dendritic cells that show oval, vesicular nuclei and ill-defined cytoplasm intimately admixed with small, mature lymphocytes. The diagnosis can be confirmed by positive immunostaining for CD21 and CD35 antigens and negative staining for cytokeratin. Unusual features in our case were the presence of prominent plasma cells and intracytoplasmic, periodic acid-Schiff stain, diastase-positive deposits, with the last not described before.

Activated peripheral blood and endothelial cells in thalassemia patients

BACKGROUND AND OBJECTIVES

Thalassemia patients have alterations in the expression of some activation and adhesion molecules on peripheral blood lymphocytes. We studied cell surface antigens on peripheral blood cells associated with the activation of these cells and soluble molecules produced by activated endothelium.

DESIGN AND METHODS

We investigated the expression of CD11b, CD18, CD35, CD43, CD44, and CD69 on the peripheral blood monocytes, Cd11b, CD18, CD35, CD43, CD44, CD67 on peripheral blood neutrophils and CD38 and CD69 on peripheral blood lymphocytes. We studied 68 transfusion-dependent thalassemics (group A), 10 transfusion non-dependent thalassemics (group B), 18 beta-thalassemia carriers (group C), and 28 normal individuals. Relative fluorescence intensity was used to determine the antigen density. Analysis was performed with an EPICS ELITE flow cytometer. Furthermore, soluble intercelullar adhesion molecule 1 (sICAM-1), soluble vascular adhesion molecule 1 (sVCAM-1), and E-selectin, tumor necrosis factor (TNF) alpha, and interleukin (IL) 1beta were measured in the plasma of patients by enzyme-linked immunometric assay.

RESULTS

The expression of CD11b, CD18, and CD69 on the monocytes of group A was significantly greater than in groups B and C and in controls, while CD44 was significantly downregulated in group A. CD11b, CD18, CD35, CD44, and CD67 on the surface of neutrophils and CD38 and CD69 on the surface of lymphocytes were also overexpressed in group A. CD44 was downregulated on the monocytes and upregulated on the neutrophils of the patients compared to controls. The levels of sICAM-1, sVCAM-1, E-selectin, TNF-alpha, and IL-1beta in the serum of patients in groups A and B were higher than those in group C and the controls.

CONCLUSION

Endothelial activation markers are significantly increased in thalassemia patients, and activated blood cells circulate in the peripheral blood. These may be related to the vascular complications in these patients and might be useful markers for the follow-up of the vascular disease.

Newly recognized cellular abnormalities in the gray platelet syndrome

The gray platelet syndrome (GPS) is a rare congenital bleeding disorder in which thrombocytopenia is associated with increased platelet size and decreased alpha-granule content. This report describes 3 new pediatric cases presenting with the classical platelet abnormalities of GPS within one family with normal parents. Examination of blood smears of the 3 patients demonstrated not only gray platelets, but also gray polymorphonuclear neutrophils (PMNs) with decreased or abnormally distributed components of secretory compartments (alkaline phosphatase, CD35, CD11b/CD18). Secondary granules were also decreased in number as assayed by immunoelectron microscopy. These data confirm that the secretory compartments in neutrophils were also deficient in this family. Megakaryocytes (MKs) were cultured from the peripheral blood CD34+ cells of the 3 patients for 14 days, in the presence of thrombopoietin and processed for immunoelectron microscopy. Although von Willebrand factor (vWF) was virtually undetectable in platelets, vWF immunolabeling was conspicuous in cultured maturing MKs, particularly within Golgi saccules, but instead of being packaged in alpha-granules, it was released into the demarcation membrane system. In contrast, P-selectin followed a more classical pathway. Double-labeling experiments confirmed that vWF was following an intracellular pathway distinct from the one of P-selectin. In these 3 new cases of GPS, the MKs appeared to abnormally process vWF, with secretion into the extracellular space instead of normal alpha-granule packaging. Furthermore, the secretory compartment of another blood cell line, the neutrophil, was also affected in this family of GPS.

Slowly progressive systemic mastocytosis with high mast-cell burden and no evidence of a non-mast-cell hematologic disorder: an example of a smoldering case?

A 43-year-old man with extensive systemic mastocytosis with poor prognostic indicators but no overt hematologic abnormality is described. This patient's clinical presentation and course are consistent with the newly proposed 'smoldering mastocytosis' category. Long-term follow-up of patients is needed to determine whether they may be at higher risk for progression into more aggressive categories.

Follicular dendritic cells in reactive and neoplastic lymphoid tissues: a reevaluation of staining patterns of CD21, CD23, and CD35 antibodies in paraffin sections after wet heat-induced epitope retrieval

Structural alterations in the meshwork of follicular dendritic cells (FDCs) are frequently found in malignant lymphomas. Formaldehyde fixation and paraffin embedding, however, have long prevented consistent detection of FDCs. Wet heat-induced epitope retrieval in Dako Target Retrieval Solution (TRS) (pH 6.0) enabled the reliable detection of FDCs through CD21, CD23, and CD35 antigens in routinely processed tissues from 11 reactive and 69 neoplastic lymphoproliferations, thus allowing the distribution of the FDCs to be reevaluated. Germinal center FDCs in lymphoid hyperplasias and expanded FDC meshworks in the 8 mantle cell lymphomas, 7 low-grade MALT lymphomas, and 6 low-grade follicular lymphomas were intensely stained with all these markers. In 6 cases of B cell chronic lymphocytic leukemia, tumor cells were CD23+. In four cases of nodular lymphocyte predominance Hodgkin's disease (HD), expanded FDC meshwork's sharply delineating negative tumor cells and their rosetting T cell, were revealed mainly with the CD21 and CD35 antibodies. Follicular dendritic cells were also demonstrated in 11 cases of grade I nodular sclerosing HD, including follicular HD. Striking dendritic cell clusters were revealed with all 3 antibodies in 9 angioimmunoblastic T cell lymphomas. Sparse or no FDC meshworks were detected in the 4 cases of grade II nodular sclerosing HD, 5 follicular lymphomas with high-grade transformation, and 5 T cell-rich B cell lymphomas. CD35 immunostaining showed the most consistent labeling in the four FDC sarcomas studied in the current article. Reproducible demonstration of FDCs in routinely processed paraffin sections with CD21, CD23, and CD35 antibodies, as presented here, provides invaluable pieces of information in the diagnosis of lymphoproliferative disorders.

Experimental culture conditions are critical for ex vivo expansion of hematopoietic cells

The ex vivo expansion of hematopoietic stem cells (HSC) for clinical use is now recognized to be a feasible and very promising approach for hematotherapy. Expansion of specific HSC subsets is required for different clinical applications, for example, to increase the number of mature cells, to produce specific cells for adoptive therapy, or to increase the number of primitive stem cells available for engraftment. Although hematopoietic growth factors can play an important role in this setting, in this review we emphasize that other variables affect the outcome of stem and progenitor cell expansion. These variables include the serum supplement, the purity of CD34(+) cells, the initial cell concentration, and the duration of culture. It is also essential to define standard culture conditions for normal stem cells and to limit or prevent expansion of residual tumor cells. In clinical applications, determination of the hematopoietic value of the expanded population is mandatory. Thus, we have to demonstrate the expansion of primitive hematopoietic progenitor and stem cells, with maintenance of their hematopoietic potential as assessed by in vitro or in vivo assays. We draw attention to the challenges in the clinical application of ex vivo expansion. These include the establishment of well-defined experimental conditions and the determination of the hematopoietic value of the expanded grafts, whatever the graft source: bone marrow, mobilized peripheral blood, or cord blood. Future studies hopefully will optimize these procedures and allow not only expansion but engineering of defined cellular functions as HSCs grow under defined conditions.

Influence of colloid fluids on polymorphonuclear granulocyte function in vivo

BACKGROUND

Granulocytes have a role in the immediate immune response. In a previous investigation we could demonstrate in vitro a moderate increase of the complement receptors CR1 (CD35) and CR3 (CD11b/CD18) on the surface of polymorphonuclear neutrophils (PMN) after incubation of whole blood with colloids. To elucidate the clinical significance, we investigated if these changes were also present in vivo.

METHODS

The study was performed prior to anaesthesia for orthopaedic surgery. A total of 60 ASA-I patients was evaluated. Patients received in a randomised manner 7 mL/kg of the following solutions: human albumin 5% (HA), gelatine 4% (GEL), hydroxyethylstarch solution 6% with MW 200,000 Da, degree of substitution 0.5 (HES), or Ringer's solution. Prior to the infusion, at the end (30 min) and again 30 min later, blood samples were taken. Blood was incubated with fluorescein-conjugated monoclonal antibodies (CD11b, CD16, CD35, CD62L) and analysed with flow cytometry.

RESULTS

HA, GEL, HES, and Ringer's solution failed to induce significant differences in the expression of complement receptors CR1 (CD35) and CR3 (CD11b/CD18), Fc gamma receptor IIIb (CD16), and of L-selectin (CD62L) receptor on the surface of PMN.

CONCLUSIONS

Application of colloids like HA, GEL, or HES in moderate amounts shows no short-term effect on adhesion or activation molecules on granulocytes. However, in high doses, infused in situations such as multiple trauma and sepsis, the consequences on the function of PMN may be speculative and require further investigations.

Use of complement receptor 1 (CD35) assay in the diagnosis and prognosis of immune complex mediated glomerulopathies

Complement Receptor 1 (CR1) is a polymorphic glycoprotein expressed on erythrocytes, leukocytes and glomerular podocytes and has a major role in immune complex processing. In addition, it regulates the complement cascade activation by preventing formation of classical and alternative pathway convertases and by acting as a cofactor for Factor I mediated cleavage of C3. In this study, we have examined the expression of erythrocyte CR1 (E-CR1) and glomerular CR1 (G-CR1) in different kinds of nephropathies using ELISA and immunofluorescence microscopy to understand their role in immune complex (IC) mediated renal diseases. E-CR1 was significantly reduced in all categories of lupus nephritis in comparison to normal subjects and non-IC renal diseases. However, other IC mediated diseases like IgA nephropathy and membranoproliferative glomerulonephritis had normal E-CR1 levels. G-CR1 showed distinct differences between IC and non-IC mediated diseases. G-CR1 was virtually absent in lupus kidneys. In other IC mediated diseases, there was a correlation of G-CR1 expression to the IC and complement fragment deposition. G-CR1 serves as a useful diagnostic marker for IC mediated diseases while E-CR1 is useful as a prognostic marker to monitor the course of disease after the treatment has initiated.