RADIORYTHMIC: Phase III, Opened, Randomized Study of Postoperative Radiotherapy Versus Surveillance in Stage IIb/III of Masaoka Koga Thymoma after Complete Surgical Resection

INTRODUCTION

Thymomas are rare intrathoracic malignancies that may be aggressive and difficult to treat. Knowledge and level of evidence for treatment strategies are mainly based on retrospective studies or expert opinion. Currently there is no strong evidence that postoperative radiotherapy after complete resection of localized thymoma is associated with survival benefit in patients. RADIORYTHMIC is a phase III, randomized trial aiming at comparing postoperative radiotherapy versus surveillance after complete resection of Masaoka-Koga stage IIb/III thymoma. Systematic central pathologic review will be performed before patient enrollment as per the RYTHMIC network pathway.

PATIENTS AND METHODS

Three hundred fourteen patients will be included; randomization 1:1 will attribute either postoperative radiotherapy (50-54 Gy to the mediastinum using intensity-modulated radiation therapy or proton beam therapy) or surveillance. Stratification criteria include histologic grading (thymoma type A, AB, B1 vs B2, B3), stage, and delivery of preoperative chemotherapy. Patient recruitment will be mainly made through the French RYTHMIC network of 15 expert centers participating in a nationwide multidisciplinary tumor board. Follow-up will last 7 years. The primary endpoint is recurrence-free survival. Secondary objectives include overall survival, assessment of acute and late toxicities, and analysis of prognostic and predictive biomarkers.

RESULTS

The first patient will be enrolled in January 2021, with results expected in 2028.

BCL2 expression but not MYC and BCL2 coexpression predicts survival in elderly patients with diffuse large B-cell lymphoma independently of cell of origin in the phase 3 LNH03-6B trial

Background

Our aim was to evaluate whether the cell of origin (COO) as defined by the Hans algorithm and MYC/BCL2 coexpression, which are the two main biological risk factors in elderly patients treated with rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine, and prednisolone (R-CHOP), maintain their prognostic value in a large prospective clinical trial.

Patients and methods

We evaluated 285 paraffin-embedded samples from patients (60-80 years of age) enrolled in the Lymphoma Study Association trial LNH03-6B who were treated with R-CHOP. We correlated the COO defined by the transcriptome according to the Wright algorithm with that defined by the Hans algorithm in a subset of 62 tumors with available frozen tissue samples.

Results

The non-germinal center B-cell-like phenotype according to the Hans algorithm and BCL2 expression (but not MYC and BCL2 coexpression) predicted worse progression-free survival [hazard ratio (HR)=1.78, P = 0.003 and HR = 1.79, P = 0.003, respectively] and overall survival (HR = 1.85, P = 0.005 and HR = 1.67, P = 0.02, respectively) independently of the International Prognostic Index. The correlation between the Hans algorithm and the Wright algorithm was 91%, with an almost perfect concordance according to a kappa test (0.81).

Conclusions

Our results suggest that immunohistochemically defined COO remains a useful tool for predicting prognosis in diffuse large B-cell lymphoma when performed under optimized standardized conditions and that BCL2 expression may help to identify elderly patients at risk for relapse and who could potentially respond to anti-BCL2 targeted agents. In this prospective phase III trial, the coexpression of MYC and BCL2 does not appear to predict worse survival.

Clinical trial Number

NCT00144755.

Diffuse large B-cell lymphoma of Waldeyer's ring has distinct clinicopathologic features: a GELA study

BACKGROUND

Diffuse large B-cell lymphomas (DLBCLs) arising in specific extranodal sites have peculiar clinicopathologic features.

PATIENTS AND METHODS

We analyzed a cohort of 187 primary Waldeyer's ring (WR) DLBCLs retrieved from GELA protocols using anthracyclin-based polychemotherapy.

RESULTS

Most patients (92%) had stage I-II disease. A germinal center B-cell-like (GCB) immunophenotype was observed in 61%, and BCL2 expression in 55%, of WR DLBCLs. BCL2, BCL6, IRF4 and MYC breakpoints were observed in, respectively, 3 of 42 (7%), 9 of 36 (25%), 2 of 26 (8%) and 4 of 40 (10%) contributive cases. A variable follicular pattern was evidenced in 30 of 68 (44%) large biopsy specimens. The 5-year progression-free survival (PFS) and the overall survival (OS) of 153 WR DLBCL patients with survival information were 69.5% and 77.8%, respectively. The GCB immunophenotype correlated with a better OS (P = 0.0015), while BCL2 expression predicted a worse OS (P = 0.037), an effect overcome by the GCB/non-GCB classification. Compared with matched nodal DLBCLs, WR DLBCLs with no age-adjusted international prognostic index factor disclosed a better 5-year PFS rate (77.5% versus 70.7%; P = 0.03).

CONCLUSIONS

WR DLBCLs display distinct clinicopathologic features compared with conventional DLBCLs, with usual localized-stage disease, common follicular features and a high frequency of GCB immunophenotype contrasting with a low rate of BCL2 rearrangements. In addition, they seem to be associated with a better outcome than their nodal counterpart.

Morphological analysis of circulating tumour cells in patients undergoing surgery for non-small cell lung carcinoma using the isolation by size of epithelial tumour cell (ISET) method

BACKGROUND AND OBJECTIVE

Recurrence rates after surgery for non-small cell lung cancer (NSCLC) range from 25 to 50% and 5-year survival is only 60-70%. Because no biomarkers are predictive of recurrence or the onset of metastasis, pathological TNM (pTNM) staging is currently the best prognostic factor. Consequently, the preoperative detection of circulating tumour cells (CTCs) might be useful in tailoring therapy. The aim of this study was to characterize morphologically any circulating non-haematological cells (CNHCs) in patients undergoing surgery for NSCLC using the isolation by size of epithelial tumour cell (ISET) method.

METHODS

Of 299 blood samples tested, 250 were from patients with resectable NSCLC and 59 from healthy controls. The presence of CNHCs was assessed blindly and independently by 10 cytopathologists on May-Grünwald-Giemsa stained filters and the cells classified into three groups: (i) malignant cells, (ii) uncertain malignant cells, and (iii) benign cells. We assessed interobserver agreement using Kappa (κ) analysis as the measure of agreement.

RESULTS

A total of 123 out of 250 (49%) patients showed CNHCs corresponding to malignant, uncertain malignant and benign cells, in 102/250 (41%), 15/250 (6%) and 6/250 (2%) cases, respectively. No CNHCs were detected in the blood of healthy subjects. Interobserver diagnostic variability was absent for CNHCs, low for malignant cells and limited for uncertain malignant and benign cells.

CONCLUSION

Identification of CTCs in resectable NSCLC patients, using ISET technology and according to cytopathological criteria of malignancy, appears to be a new and promising field of cytopathology with potential relevance to lung oncology.

The expression of 16 genes related to the cell of origin and immune response predicts survival in elderly patients with diffuse large B-cell lymphoma treated with CHOP and rituximab

Gene expression profiles have been associated with clinical outcome in patients with diffuse large B-cell lymphoma (DLBCL) treated with anthracycline-containing chemotherapy. Using Affymetrix HU133A microarrays, we analyzed the lymphoma transcriptional profile of 30 patients treated with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) and 23 patients treated with rituximab (R)-CHOP in the Groupe d'Etude des Lymphomes de l'Adulte clinical centers. We used this data set to select transcripts showing an association with progression-free survival in all patients or showing a differential effect in the two treatment groups. We performed real-time quantitative reverse transcription-PCR in the 23 R-CHOP samples of the screening set and an additional 44 R-CHOP samples set to evaluate the prognostic significance of these transcripts. In these 67 patients, the level of expression of 16 genes and the cell-of-origin classification were significantly associated with overall survival, independently of the International Prognostic Index. A multivariate model comprising four genes of the cell-of-origin signature (LMO2, MME, LPP and FOXP1) and two genes related to immune response, identified for their differential effects in R-CHOP patients (APOBEC3G and RAB33A), demonstrated a high predictive efficiency in this set of patients, suggesting that both features affect outcome in DLBCL patients receiving immunochemotherapy.

Primary mediastinal anaplastic alk-1-positive large-cell lymphoma of T/NK-cell type expressing CD20

We describe an unusual case of ALK-1-positive primary mediastinal lymphoma with the morphology of an anaplastic large-cell lymphoma (ALCL) of T/NK cell type but expressing CD20. This tumour had T/NK morphology and immunophenotype, as demonstrated by its expression of CD30, EMA, ALK-1, CD7 and TiA-1 and the lack of expression of B-cell markers other than CD20. The significance of such a co-expression of a B cell-associated antigen in a case of ALCL of T/NK cell type is discussed.

Significantly improved PCR-based clonality testing in B-cell malignancies by use of multiple immunoglobulin gene targets. Report of the BIOMED-2 Concerted Action BHM4-CT98-3936

Polymerase chain reaction (PCR) assessment of clonal immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements is an important diagnostic tool in mature B-cell neoplasms. However, lack of standardized PCR protocols resulting in a high level of false negativity has hampered comparability of data in previous clonality studies. In order to address these problems, 22 European laboratories investigated the Ig/TCR rearrangement patterns as well as t(14;18) and t(11;14) translocations of 369 B-cell malignancies belonging to five WHO-defined entities using the standardized BIOMED-2 multiplex PCR tubes accompanied by international pathology panel review. B-cell clonality was detected by combined use of the IGH and IGK multiplex PCR assays in all 260 definitive cases of B-cell chronic lymphocytic leukemia (n=56), mantle cell lymphoma (n=54), marginal zone lymphoma (n=41) and follicular lymphoma (n=109). Two of 109 cases of diffuse large B-cell lymphoma showed no detectable clonal marker. The use of these techniques to assign cell lineage should be treated with caution as additional clonal TCR gene rearrangements were frequently detected in all disease categories. Our study indicates that the BIOMED-2 multiplex PCR assays provide a powerful strategy for clonality assessment in B-cell malignancies resulting in high Ig clonality detection rates particularly when IGH and IGK strategies are combined.

Improved reliability of lymphoma diagnostics via PCR-based clonality testing: — Report of the BIOMED-2 Concerted Action BHM4-CT98-3936

The diagnosis of malignant lymphoma is a recognized difficult area in histopathology. Therefore, detection of clonality in a suspected lymphoproliferation is a valuable diagnostic criterion. We have developed primer sets for the detection of rearrangements in the B- and T-cell receptor genes as reliable tools for clonality assessment in lymphoproliferations suspected for lymphoma. In this issue of Leukemia, the participants of the BIOMED-2 Concerted Action CT98-3936 report on the validation of the newly developed clonality assays in various disease entities. Clonality was detected in 99% of all B-cell malignancies and in 94% of all T-cell malignancies, whereas the great majority of reactive lesions showed polyclonality. The combined BIOMED-2 results are summarized in a guideline, which can now be implemented in routine lymphoma diagnostics. The use of this standardized approach in patients with a suspect lymphoproliferation will result in improved diagnosis of malignant lymphoma.

Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936

Polymerase chain reaction (PCR) assessment of clonal T-cell receptor (TCR) and immunoglobulin (Ig) gene rearrangements is an important diagnostic tool in mature T-cell neoplasms. However, lack of standardized primers and PCR protocols has hampered comparability of data in previous clonality studies. To obtain reference values for Ig/TCR rearrangement patterns, 19 European laboratories investigated 188 T-cell malignancies belonging to five World Health Organization-defined entities. The TCR/Ig spectrum of each sample was analyzed in duplicate in two different laboratories using the standardized BIOMED-2 PCR multiplex tubes accompanied by international pathology panel review. TCR clonality was detected in 99% (143/145) of all definite cases of T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma (unspecified) and angioimmunoblastic T-cell lymphoma (AILT), whereas nine of 43 anaplastic large cell lymphomas did not show clonal TCR rearrangements. Combined use of TCRB and TCRG genes revealed two or more clonal signals in 95% of all TCR clonal cases. Ig clonality was mostly restricted to AILT. Our study indicates that the BIOMED-2 multiplex PCR tubes provide a powerful strategy for clonality assessment in T-cell malignancies assisting the firm diagnosis of T-cell neoplasms. The detected TCR gene rearrangements can also be used as PCR targets for monitoring of minimal residual disease.

Polymerase chain reaction-based clonality testing in tissue samples with reactive lymphoproliferations: usefulness and pitfalls. A report of the BIOMED-2 Concerted Action BMH4-CT98-3936

Lymphoproliferations are generally diagnosed via histomorphology and immunohistochemistry. Although mostly conclusive, occasionally the differential diagnosis between reactive lesions and malignant lymphomas is difficult. In such cases molecular clonality studies of immunoglobulin (Ig)/T-cell receptor (TCR) rearrangements can be useful. Here we address the issue of clonality assessment in 106 histologically defined reactive lesions, using the standardized BIOMED-2 Ig/TCR multiplex polymerase chain reaction (PCR) heteroduplex and GeneScan assays. Samples were reviewed nationally, except 10% random cases and cases with clonal results selected for additional international panel review. In total 75% (79/106) only showed polyclonal Ig/TCR targets (type I), whereas another 15% (16/106) represent probably polyclonal cases, with weak Ig/TCR (oligo)clonality in an otherwise polyclonal background (type II). Interestingly, in 10% (11/106) clear monoclonal Ig/TCR products were observed (types III/IV), which prompted further pathological review. Clonal cases included two missed lymphomas in national review and nine cases that could be explained as diagnostically difficult cases or probable lymphomas upon additional review. Our data show that the BIOMED-2 Ig/TCR multiplex PCR assays are very helpful in confirming the polyclonal character in the vast majority of reactive lesions. However, clonality detection in a minority should lead to detailed pathological review, including close interaction between pathologist and molecular biologist.

Perioperative analysis of biopsies issued from mediastinoscopy

BACKGROUND

The objective of this study was to evaluate frozen sections of samples obtained at mediastinoscopy for their clinical usefulness.

METHODS

This study retrospectively reviewed the records of all patients who underwent mediastinoscopy with perioperative frozen sections in a 1-year period.

RESULTS

A total of 123 consecutive patients underwent the procedure. There were no false-positive results. Of the 71 malignant proliferations, 67 were diagnosed from frozen sections. The technique never failed to establish the absence of mediastinal nodal involvement in patients with suspected or proven lung tumors and enlarged nodes (n = 18) who underwent immediate thoracotomy. Frozen sections allowed recognition (n = 36) or strong suspicion (n = 4) of N2 disease in patients subsequently treated by induction chemotherapy. The technique never failed to establish the nonresectability of lung cancer in patients for whom this condition was suspected perioperatively (clinical stage IIIb; n = 10).

CONCLUSIONS

Mediastinoscopy with frozen sections remains an extremely useful tool for the management of paratracheal or subcarinal mediastinal disease.

Peroperative frozen section analysis of TTF-1 antigen expression

BACKGROUND

The assessment of thyroid transcription factor 1 (TTF-1) expression is a useful way to investigate the origin of lung adenocarcinomas or large cell carcinomas when dealing with a solitary lung nodule in a patient with a history of extrathoracic cancer. However, if immunohistological analysis has not been performed before surgery, a peroperative frozen section may be insufficient to distinguish between a primary pulmonary tumour and a metastatic tumour.

AIMS

To develop a technique for the rapid assessment of TTF-1 expression that could improve the ability of frozen section peroperative histological diagnosis to answer such questions.

METHODS

A rapid immunohistochemical technique (lasting 30 minutes) to assess the expression of TTF-1 was developed and tested.

RESULTS

Among the 45 interpretable cases, results of frozen section immunohistochemistry were similar to those found by the standard immunohistochemical technique for the expression of TTF-1.

CONCLUSIONS

This technique enables TTF-1 to be analysed peroperatively, but further prospective studies are needed to assess its usefulness in routine practice.

Blood vessel invasion in resected non small cell lung carcinomas is predictive of metastatic occurrence

Prognosis of patients with non small cell lung cancer (NSCLC) remains difficult to assess, even after adjustment for pathological stage. Prognostic value of numerous biological markers has been evaluated, with conflicting results. Data of 86 patients with NSCLC treated by surgery were collected with clinical characteristics, histopathological data including tumor differentiation and status of blood and lymphatic vessel invasion and evaluation by immunohistochemistry of Rb, Bcl-2 and Ki-67 expression. Prognostic values for overall survival (OS) and event-free survival (EFS) were analyzed by the log tank test and the multivariable Cox model. Using univariable analyses, pT, pN, poor differentiation or large cell subtype were associated with a poor OS, while lymphatic and/or blood vessel invasion were associated with a short EFS. None of the molecular markers had a significant prognostic value for either outcome. In multivariable analyses, only stage remained of prognostic value for OS. Interestingly, the presence of blood vascular invasion in the tumor was significantly predictive for subsequent metastatic occurrence in stages I and II. This feature might, therefore, be relevant for administration of adjuvant therapy in completely resected NSCLC.

Coexistence of acute cellular rejection and lymphoproliferative disorder in a lung transplant patient

We report the case of a 37-year-old man who underwent bilateral lung transplantation for end-stage cystic fibrosis. Two months after his operation, a computed tomographic scan showed multifocal nodules throughout both lungs. Endobronchial biopsies revealed an Epstein-Barr virus-associated B-cell lymphoproliferation. Transbronchial biopsies revealed perivascular lymphoid infiltrates composed of predominantly small T lymphocytes. These perivascular infiltrates were retrospectively considered to be an acute cellular rejection rather than the periphery of the lymphoproliferative disorder. This opinion was based on several arguments: (a) a decrease in dosage of maintenance immunosuppression led to total regression of the lymphoproliferation but did not affect the perivascular lymphoid infiltrates; (b) the treatment of the acute cellular rejection temporarily induced the disappearance of the perivascular infiltrates; (c) the expression of Epstein-Barr virus was not detected in the perivascular infiltrates; and (d) on autopsy, performed 1 year later, severe obliterative bronchiolitis lesions were discovered, for which acute cellular rejection is the main risk factor. These observations point to the possibility that acute cellular rejection and an Epstein-Barr virus-associated lymphoproliferative disorder may coexist.

Mantle cell lymphoma, in leukaemic phase with prominent splenomegaly. A report of eight cases with similar clinical presentation and aggressive outcome

Mantle cell lymphoma (MCL) is a well-defined peripheral B-cell lymphoma usually diagnosed upon peripheral lymph node biopsy. We report eight cases of peripheral B-cell leukaemia that demonstrate presumptive evidence of mantle cell characteristics. The patients had a median age of 68.5 years, and five were male. All presented with an enlarged spleen without any peripheral lymphadenopathies, and they were leukaemic at presentation (median lymphocytosis, 38x10(9)/l). Morphological diagnosis of MCL was very difficult in five cases but easier in three because we were able to analyse either pre- or post-mortem lymph nodes and spleen. The immunophenotype of blood lymphocytosis using flow cytometry, the presence of a t(11;14)(q13;q32) and a cyclin D1 expression by leukaemic cells all fit with the diagnosis of MCL. All patients progressed and died with a median overall survival of 8 months. Multifocal areas of transformation in blastoid or large cell variants were observed in the three autopsied patients. In summary, one should consider the diagnosis of MCL at presentation in leukaemic phase even in the absence of peripheral adenopathies.

Prognostic significance of survivin expression in diffuse large B-cell lymphomas

Survivin is an inhibitor of apoptosis overexpressed in various human cancers but undetectable in normal differentiated tissues. A potential expression and prognostic significance of survivin was studied in 222 patients with diffuse large B-cell lymphomas (centroblastic, 96%; immunoblastic, 4%). All patients were enrolled between 1987 and 1993 (median follow-up, 7 years) in the LNH87 protocol of the Groupe d'Etudes des Lymphomes de l'Adulte (GELA) and treated either with the reference ACVBP arm (doxorubicin, cyclophosphamide, vindesine, bleomycin, and prednisone)[AU3A] (n = 79) or other experimental anthracycline-containing regimens (n = 143). The characteristics of these patients were median age of 56 years; serum lactate dehydrogenase (LDH) greater than 1N, 60%; stage III-IV, 55%; performance status, according to the Eastern Cooperative Oncology Group (ECOG) scale, more than 1, 23%; extranodal sites more than 1, 29%; mass more than 10 cm, 44%; bone marrow involvement, 15%. Of the 222 patients studied, 134 (60%) revealed survivin expression in virtually all tumor cells by immunohistochemistry. The overall 5-year survival rate was significantly lower in patients with survivin expression than in those without (40% vs 54%, P =.02). Multivariate analysis incorporating prognostic factors from the International Prognostic Index (IPI) identified survivin expression as an independent predictive parameter on survival (P =.03, relative risk [RR] = 1.6) in addition to LDH (P =.02, RR = 1.6), stage (P =.03, RR = 1.7), and ECOG scale (P =.05, RR = 1.6). A second analysis incorporating IPI as a unique parameter demonstrated that survivin expression (P =.02, RR = 1.6) remained a prognostic factor for survival independently of IPI (P =.001, RR = 1.5). Survivin expression may be considered a new unfavorable prognostic factor of diffuse large B-cell lymphoma. (Blood. 2000;96:1921-1925)

Retinal dysplasia in mice lacking p56lck

The product of the proto-oncogene p56lck is a non-receptor tyrosine kinase member of the Src family. It is found in T cells (Marth et al., 1985, 1988) and in the mouse brain (Omri et al., 1996; Van Tan et al., 1996). In this report, we describe experiments showing that Lck is present in the mouse retina neurons. Lck gene expression was identified after isolating and sequencing the specific 5' and 3' part of the cDNA obtained by RT-PCR. In adult retina Lck immunoreactivity was most abundant in photoreceptor cells and within the outer plexiform layers. Staining was also observed in the inner nuclear and plexiform layers. In transgenic mice, the disruption of the Lck gene had serious consequences on the organization of the retina causing retinal dysplasia. These mice have partial retinal detachment with infolding and rosette formation in the photoreceptor sheet. These retinal abnormalities observed in Lck deficient mice lead to the loss of normal architecture of the photoreceptor and the inner nuclear layers, and provide an important role of Lck protein in the retina development. The lack of the Lck protein produces a spectrum of retinal pathology that resembles human retinopathy of prematurity (ROP).

Differential requirement for p56lck in fetal and adult thymopoiesis

The protein tyrosine kinase p56lck is critical for the generation of mature thymocytes in adult mice. However its requirement during the maturation of thymocytes from the fetal to the adult stage has not been clearly defined. We analyzed prenatal and postnatal thymocyte maturation in mice deficient for p56lck (lck[-/-]). Before birth, lck appears to play a crucial role in the expansion and proliferation of CD4+CD8+ double positive thymocytes, whereas proliferation and absolute numbers of CD4-CD8- double negative thymocyte precursors remained within the normal range until the end of the second week postnatal. Three weeks after birth, the total numbers of double negative and immature single positive thymocytes underwent a dramatic reduction that correlated with a decrease in the double positive population. This ontogenic defect was associated with a significant decrease in the proliferation rates of thymocyte precursors. Our data suggest that signaling via p56lck kinase is differentially required within a given phenotypically defined thymocyte subpopulation, depending on its stage of thymocyte maturation.

Detection of bcl-2 rearrangement in HIV-related follicular lymphoid hyperplasia

Rearrangement of the bcl-2 gene at the MBR (major breakpoint region) locus with the immunoglobulin heavy-chain joining region has been reported in a high proportion of follicular lymphomas. This rearrangement has also been reported in very few normal B cells of the blood, tonsils, follicular lymphoid hyperplasia (FLH) of the lymph nodes. HIV infection is often associated at the onset of the disease with FLH, but the presence of rearranged bcl-2 B cells in these lymph nodes has not been described. In using a standard PCR assay with Southern blot or a semi-nested PCR on 48 cases of FLH, we demonstrated that there were a few bcl-2 rearranged B cells in HIV FLH, at almost the same level as that in non-HIV-related FLH. The usual absence of bcl-2 rearrangement in the HIV-associated B-cell lymphomas suggests that the bcl-2 oncogene in the rearranged B cells of FLH is not cooperating with other oncogenes during HIV lymphomagenesis.

Allo-skin graft rejection, tumor rejection and natural killer activity in mice lacking p56lck

Mice lacking the p56lck molecule (lck -/-) have a profound block in the maturation of thymocytes and a greatly reduced number of peripheral mature T cells. To analyze further the functions of the T cells developed in lck -/- mice in vivo, we evaluated the ability of lck -/- mice to reject allo-skin grafts and methylcholanthrene (MCA)-induced syngeneic fibrosarcoma, and also examined the biological activity of lck -/- natural killer (NK) cells. Mice lacking p56lck failed to reject skin grafts from either MHC-disparate or minor-histocompatibility-different donors, even after they had been primed with donor spleen cells. They also failed to reject the MCA-induced immunogenic syngeneic fibrosarcoma, MC57X. NK activity in mice lacking p56lck was normal, and there were no differences in the NK cell activation induced by poly(I).poly(C) stimulation or interleukin-2 stimulation (lymphokine-activated killer induction) between mice lacking p56lck and their immunocompetent heterozygous littermates. NK cells lacking p56lck mediated a normal antibody-dependent cell-mediated cytotoxicity (ADCC) response. The results of this study indicate that the loss of p56lck severely impairs the effectors of the immune system which mediate the rejection of allo-skin grafts and syngeneic tumors. The normal NK activity in lck -/- mice suggests that p56lck is not required for the development and activation of NK cells.

Impaired development of V gamma 3 dendritic epidermal T cells in p56lck protein tyrosine kinase-deficient and CD45 protein tyrosine phosphatase-deficient mice

To determine whether p56lck protein tyrosine kinase and CD45 protein tyrosine phosphatase are involved in the signal transduction during intrathymic differentiation of gamma/delta T cells, we have examined the development of T cells expressing V gamma 3 T cell receptor (TCR) in mice deficient for either protein. The skin from both mice contained significantly reduced numbers of dendritic epidermal T cells expressing decreased levels of V gamma 3 TCR at the cell surface. Analysis of the fetal thymus from these mice suggested that maturation of V gamma 3 thymocytes was blocked at the immature stage that was characterized by the low level of V gamma 3 TCR and the high level of heat stable antigen. These results imply that both p56lck and CD45 are involved in the signal transduction during maturation of V gamma 3 T cells in the fetal thymus.

Peripheral T cells in mice lacking p56lck do not express significant antiviral effector functions

Mutant mice lacking p56lck, the T cell-specific protein tyrosine kinase, have a profound thymic atrophy and possess only an immature thymocyte population. Only 5 to 10% of normal levels of mature T cells (TCR-alpha beta+, CD4+, or CD8+) are present in these mice. These T cells, but also B cells of mutant mice, can be activated by mitogens, and T cells proliferate upon stimulation with IL-2 or mAb against the TCR. Thus, it appears that selected T cells can mature without lck and that they may have circumvented the need for this enzyme. This study evaluated the capacity of these mice to generate antiviral immune responses: 1) mutant mice failed to generate virus-specific CTL after acute infection with lymphocytic choriomeningitis virus (LCMV) or vaccinia virus. 2) LCMV was not cleared from the spleen on day 10 after infection. 3) Infection of LCMV into footpads of mutant mice did not induce a T cell-dependent swelling reaction. 4) Intracerebral inoculation with LCMV did not induce in mutant mice any clinical signs of sickness. 5) Vesicular stomatitis virus (VSV)-primed mutant mice could not eliminate nucleoprotein of VSV recombinant vaccinia virus upon intracerebral infection. 6) VSV infection of mutant mice elicited normal, specific T cell-independent IgM responses, but no significant switch to IgG. These results show that, despite the presence of in vitro activatable CD8+ and CD4+ T cells in the mutant mice, no biologically relevant functions can be detected. Therefore, these data indicate that p56lck is directly or indirectly crucially involved in in vivo Ag-induced T cell responses.

Peripheral T cells in mice lacking p56lck do not express significant antiviral effector functions

Mutant mice lacking p56lck, the T cell-specific protein tyrosine kinase, have a profound thymic atrophy and possess only an immature thymocyte population. Only 5 to 10% of normal levels of mature T cells (TCR-alpha beta+, CD4+, or CD8+) are present in these mice. These T cells, but also B cells of mutant mice, can be activated by mitogens, and T cells proliferate upon stimulation with IL-2 or mAb against the TCR. Thus, it appears that selected T cells can mature without lck and that they may have circumvented the need for this enzyme. This study evaluated the capacity of these mice to generate antiviral immune responses: 1) mutant mice failed to generate virus-specific CTL after acute infection with lymphocytic choriomeningitis virus (LCMV) or vaccinia virus. 2) LCMV was not cleared from the spleen on day 10 after infection. 3) Infection of LCMV into footpads of mutant mice did not induce a T cell-dependent swelling reaction. 4) Intracerebral inoculation with LCMV did not induce in mutant mice any clinical signs of sickness. 5) Vesicular stomatitis virus (VSV)-primed mutant mice could not eliminate nucleoprotein of VSV recombinant vaccinia virus upon intracerebral infection. 6) VSV infection of mutant mice elicited normal, specific T cell-independent IgM responses, but no significant switch to IgG. These results show that, despite the presence of in vitro activatable CD8+ and CD4+ T cells in the mutant mice, no biologically relevant functions can be detected. Therefore, these data indicate that p56lck is directly or indirectly crucially involved in in vivo Ag-induced T cell responses.

Profound block in thymocyte development in mice lacking p56lck

The protein Lck (p56lck) has a relative molecular mass of 56,000 and belongs to the Src family of tyrosine kinases. It is expressed exclusively in lymphoid cells, predominantly in thymocytes and peripheral T cells. Lck associates specifically with the cytoplasmic domains of both CD4 and CD8 T-cell surface glycoproteins and interacts with the beta-chain of the interleukin-2 receptor, which implicates Lck activity in signal transduction during thymocyte ontogeny and activation of mature T cells. Here we generate an lck null mutation by homologous recombination in embryonic stem cells to evaluate the role of p56lck in T-cell development and activation. Lck-deficient mice show a pronounced thymic atrophy, with a dramatic reduction in the double-positive (CD4+CD8+) thymocyte population. Mature, single-positive thymocytes are not detectable in these mice and there are only very few peripheral T cells. These results illustrate the crucial role of this T-cell-specific tyrosine kinase in the thymocyte development.

Paraganglioma of the urinary bladder: immunohistochemical, ultrastructural, and DNA flow cytometric studies

Primary paraganglioma arises infrequently in the urinary bladder. We present the clinicopathologic, immunohistochemical, ultrastructural, and DNA flow cytometric findings in three cases (one man and two women). Ages at diagnosis were 19, 35, and 45 years. One female presented with paroxysmal headaches and hypertension that followed urination; the remaining two patients presented with hematuria. Immunohistochemical studies revealed positive reactivity for chromogranin (three patients), met-enkephalin (three), leu-enkephalin (three), vasoactive intestinal polypeptide (two), serotonin (one), and S-100 protein (one; sustentacular cells only). Neurosecretory granules were identified in all cases; in the patient with hypertension, the granules were small with eccentric cores similar to those of adrenal pheochromocytomas. A nondiploid DNA flow cytometric pattern was present in all three patients, an aneuploid pattern was present in two, and a tetraploid pattern was present in one. After diagnosis, one patient was alive without progression at 7 years, one died of an uncertain cause at 5 years, and one suffered multiple recurrences over a 24-year period before developing metastatic disease. While the presence of aneuploidy has been shown to be a predictor of malignant behavior in adrenal pheochromocytomas, our study illustrates that DNA ploidy cannot be used as a diagnostic criterion for malignancy in urinary bladder paraganglioma.