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Chromosomal rearrangements observed in T-cell prolymphocytic leukemia involve the translocation of one T-cell receptor gene to either chromosome 14q32 or Xq28, deregulating the expression of cellular protooncogenes of unknown function, such as TCL1 or its homologue, MTCP1. In the human hematopoietic system, TCL1 expression is predominantly observed in developing B lymphocytes, whereas its overexpression in T cells causes mature T-cell proliferation in transgenic mice. In this study, using a newly generated monoclonal antibody against recombinant TCL1 protein, we extended our analysis mainly by immunohistochemistry and also by fluorescence-activated cell sorting and Western blot to a large tumor lymphoma data bank including 194 cases of lymphoproliferative disorders of B- and T-cell origin as well as reactive lymphoid tissues. The results obtained show that in reactive lymphoid tissues, TCL1 is strongly expressed by a subset of mantle zone B lymphocytes and is expressed to a lesser extent by follicle center cells and by scattered interfollicular small lymphocytes. In B-cell neoplasia, TCL1 was expressed in the majority of the cases, including lymphoblastic lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma (60%), and primary cutaneous B cell lymphoma (55%). TCL1 expression was observed in both the cytoplasmic and nuclear compartments, as confirmed by Western blot analysis. Conversely, TCL1 was not expressed in Hodgkin/Reed-Sternberg cells, multiple myelomas, marginal zone B-cell lymphomas, CD30+ anaplastic large cell lymphoma, lymphoblastic T-cell lymphoma, peripheral T-cell lymphoma, and mycosis fungoides. These data indicate that TCL1 is expressed in more differentiated B cells, under both reactive and neoplastic conditions, from antigen committed B cells and in germinal center B cells and is down-regulated in the latest stage of B-cell differentiation.

The human BCL-6 gene, which is rearranged in approximately 30% of diffuse large B cell lymphomas, encodes a 706-amino-acid nuclear protein of the Kruppel-type zinc finger transcription factors mainly expressed in normal germinal center B cells and related lymphomas. Four monoclonal antibodies (PG-B6, PG-B6a, PG-B6p, and PG-B6m), specifically directed against the human BCL-6 protein, were generated by immunizing BALB/c mice with a recombinant protein corresponding to the BCL-6 amino-terminal region (amino acids 3 to 484). The PG-B6 monoclonal antibody reacted with a BCL-6 epitope sensitive to fixatives and preserved in all mammalian species. PG-B6a (a is for avian) recognized the most evolutionarily conserved BCL-6 epitope (expressed in all animal species including avian). PG-B6p (p is for paraffin) recognized a fixative-resistant epitope of BCL-6 that was detectable on paraffin sections after microwave heating in 1 mmol/L EDTA buffer. PG-B6m (m is for mantle) was the least specific monoclonal antibody as, in addition to BCL-6, it reacted with a yet undefined antigen selectively located in the cytoplasm of mantle and marginal zone B cells. All monoclonal antibodies detected strong nuclear expression of BCL-6 in follicular lymphomas, diffuse large B cell lymphomas, Burkitt's lymphomas, and nodular, lymphocyte-predominance Hodgkin's disease. In diffuse large B cell lymphomas, BCL-6 expression was independent of BCL-6 gene rearrangements and did not correlate with expression of other markers or the proliferation index. BCL-6 was not expressed in B-CLL, hairy cell leukemia, mantle-cell- and marginal-zone-derived lymphomas. Labeling of paraffin sections with PG-B6p proved useful for differentiating proliferation centers in B-CLL (BCl-2+/BCL-6-) from trapped germinal centers in mantle cell lymphomas (BCL-2-/BCL-6+) and for identifying neoplastic cells in cases of nodular, lymphocyte-predominance Hodgkin's disease. Because of their high specificity, wide reactivity in humans and animal species including avians (PG-B6a), and suitability for labeling routine paraffin sections (PG-B6p), the reagents described in this paper should prove valuable in both research and diagnostics.

A significant correlation between bone marrow (BM) histology, survival and disease progression (DP) probability has been observed by several authors in chronic lymphocytic leukemia (CLL). The prognostic value of BM histologic patterns on survival and disease progression probability was investigated in 335 B-CLL patients.Actuarial survival probability estimated by univariate analysis proved to be significantly influenced by stage (p0.0001), BM histology (p = 0.01), and by the following parameters: anemia (p = 0.0005), splenomegaly (p0.001), CLL-related symptoms (p0.01), thrombocytopenia (p0.01), number of involved nodal areas (p = 0.01) and peripheral lymphocyte count over 30 x 10(9)/L (p0.05). In this series we did not detect a discriminating prognostic effect for BM histology within the individual stages. Cox multivariate regression analysis failed to demonstrate a significant value for BM histology, while stage and anemia emerged as the best prognostic variables. Actuarial DP free probability in 294 untreated patients with A and B stages was significantly related to stage (p0.00001) and to BM pattern (p = 0.01).Despite the clear correlation between the D pattern of BM involvement and advanced and early progressive disease, we were unable to demonstrate an independent prognostic value for BM histology. These findings suggest that stage emerged as the best predictive factor of survival probability in our B-CLL patients.

The expression of very late activation antigens (VLAs)-1/6 was correlated with that of the VLA ligands fibronectin, laminin, collagen, and vascular cell adhesion molecule-1 in sections of normal thymus, in thymocyte suspensions, and in 10 cases of thymoma. Capsular epithelial cells are VLA-2+, VLA-3+, and VLA-6+ and face the thymic basement membrane, which is rich in fibronectin, laminin, and collagen type IV. Cortical epithelial cells are VLA-2+ and are embedded in a reticular meshwork of nonorganized extracellular matrix (ECM) that is rich in fibronectin. Cortical thymocytes, identified as CD3dim cells by using immunofluorescence in suspension, are highly positive for VLA-4, a fibronectin ligand. Most cortical macrophages are positive for vascular cell adhesion molecule-1, a molecule recognized by VLA-4. Medullary epithelial cells are VLA-2+/VLA-3+ and are codistributed with fibrous strands of organized ECM that are positive for fibronectin, collagen, and laminin. Medullary thymocytes, identified as CD3bright cells, are positive for VLA-4 and VLA-6, a ligand for laminin. Our findings suggest that intrathymic thymocyte maturation is associated with changes in expression of VLA molecules, which are apparently correlated with the presence of VLA ligands in the tissue microenvironment. Thymomas were classified as cortical (three), common (five), or medullary (two) type. Expression of VLA molecules and distribution of ECM in the three histological subtypes were reminiscent of those observed in the respective regions of the normal thymus. All cases of thymoma were characterized by overexpression of VLA molecules on neoplastic cells, which was associated with increased deposition of organized ECM rich in fibronectin, laminin, and collagen.

The immunocytochemical expression of intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), endothelial leukocyte adhesion molecule (ELAM-1), endothelial cell adhesion molecule (EndoCAM CD31), and HLA-DR antigens was investigated in sections of 24 reactive lymph nodes and in 15 cases of Hodgkin's disease. ICAM-1 was detected in sinus macrophages, follicular dendritic reticulum cells (FDRCs), interdigitating reticulum cells (IDRCs), epithelioid macrophages, Hodgkin's cells (HCs), and vascular endothelium. ICAM-1 expression was often associated with that of HLA-DR antigens. VCAM-1 was detected in FDRCs, in fibroblast reticulum cells (FRCs), in macrophages, and in rare blood vessels. EndoCAM (CD31) was constitutively expressed in all types of endothelial cells, sinus macrophages, and in epithelioid granulomas. ELAM-1 was selectively expressed by activated endothelial cells of high endothelium venules (HEVs). When expression of the inducible adhesion molecules ICAM-1, VCAM-1 and ELAM-1 was comparatively evaluated in HEVs, it was found that ICAM-1 + HEVs were present in all reactive and HD nodes, whereas ELAM-1 and/or VCAM-1 were expressed only in those pathologic conditions characterized by high levels of interleukin-1/tumor necrosis factor (IL-1/TNF) production, such as granulomatosis and Hodgkin's disease. In Hodgkin's disease, the expression of ELAM-1/VCAM-1 was more pronounced in cases of nodular sclerosis and was associated with a significantly higher content of perivascular neutrophils.

Natural killer (NK) activity against K-562 myeloid cell line was evaluated in 21 spleens and 14 lymph nodes from patients with Hodgkin's disease (HD). NK activity of eight HD-involved (HD+) spleens [556 lytic units (LU)] was found 5-fold higher than that of 13 HD-uninvolved (HD-) spleens (112 LU) (p less than 0.01). Moreover, NK activity of HD+ spleens was significantly different (p less than 0.05) from that of three spleens involved by non-HD lymphoma (100 LU). NK activity of four spleens from nonneoplastic patients (250 LU) was intermediate between those of HD+ and HD- spleens. Lymph node cells were about 10-fold less cytotoxic. NK activity of seven HD+ lymph nodes (43 LU) was 3-fold higher than that of three lymph nodes involved by non-HD lymphoma (8 LU). However, these differences were not statistically significant. Our data are compatible with increased NK activity in HD+ tissues as well as with depressed NK activity in HD- tissues. The observation that NK activity of peripheral blood leukocytes from nine HD patients (116 LU) (p less than 0.05 only at 100:1 effector:target cell ratio) may support the latter interpretation. Partial characterization of effector cells in HD+ and in HD- spleens indicated that, in both instances NK cells were nonadherent and almost equally distributed between the erythrocyte-negative and -positive cell fractions. Finally, NK activity of both HD+ and HD- spleen cells could be further potentiated in vitro by interferon.

We report a unique case of primary myxoid chondrosarcoma in the posterior mediastinum. This lesion clinically mimicked a neurogenic tumor due to its location and dumbbell appearance. The histogenesis of this tumor is discussed and a skeletal origin from the thoracic vertebrae is suggested. It is concluded that myxoid chondrosarcoma has to be distinguished for the differential diagnosis among the long list of myxoid tumors arising in the posterior mediastinum.