Ki-1 is a monoclonal antibody (raised against a Hodgkin's disease- derived cell line) that, in biopsy tissue affected by Hodgkin's disease, reacts selectively with Reed-Sternberg cells. The expression of Ki-1 antigen has been analyzed by immunocytochemical techniques in a wide range of human tissue and cell samples, including fetal tissue, malignant lymphomas (290 cases), and mitogen- and virus-transformed peripheral blood lymphocytes. The antigen was detectable on a variable proportion of cells in all cases of lymphomatoid papulosis and angio- immunoblastic lymphadenopathy and in 28% of the cases of peripheral T cell lymphomas (including lympho-epithelioid lymphomas). It was also expressed (more strongly) on tumor cells in 45 cases of diffuse large- cell lymphoma, most of which had originally been diagnosed as malignant histiocytosis or anaplastic carcinoma, because of their bizarre morphology. However, all of these cases lacked macrophage and epithelial antigens. Thirty-five cases expressed T cell-related antigens (associated in nine cases with the coexpression of B cell- related antigens), seven bore B cell-related antigens alone, and three were devoid of T and B cell markers. DNA hybridization with a JH specific probe showed a germline configuration in 11 cases of T cell phenotype, in two cases lacking T and B cell antigens, and in one case of mixed T/B phenotype, while rearrangement was found in two cases of clear B cell type and in one mixed T/B case. Expression of the Ki-1 antigen could be induced, together with interleukin 2 (IL 2) receptor, on normal lymphoid cells of both T and B cell type by exposure to phytohemagglutinin, human T leukemia viruses, Epstein-Barr virus, or Staphylococcus aureus. The results obtained indicate that Ki-1 antigen is an inducible lymphoid-associated molecule that identifies a group of hitherto poorly characterized normal and neoplastic large lymphoid cells. Tumors comprised solely of these cells show both morphological and immunological similarities to the neoplastic cells in Hodgkin's disease. This suggests that both disorders represent the neoplastic proliferation of activated lymphoid cells of either T cell or, less commonly, B cell origin. Disorders in which only a minority of cells express Ki-1 antigen (lymphomatoid papulosis, angio-immunoblastic lymphadenopathy, and certain T cell lymphomas) probably represent lesions in which only some of the abnormal cells have transformed into an “activation state.” In direct support of this view is the finding that the Ki-1 expression in these lesions is accompanied by the expression of HLA-DR and IL 2 receptors.

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Ki-1 is a monoclonal antibody (raised against a Hodgkin's disease- derived cell line) that, in biopsy tissue affected by Hodgkin's disease, reacts selectively with Reed-Sternberg cells. The expression of Ki-1 antigen has been analyzed by immunocytochemical techniques in a wide range of human tissue and cell samples, including fetal tissue, malignant lymphomas (290 cases), and mitogen- and virus-transformed peripheral blood lymphocytes. The antigen was detectable on a variable proportion of cells in all cases of lymphomatoid papulosis and angio- immunoblastic lymphadenopathy and in 28% of the cases of peripheral T cell lymphomas (including lympho-epithelioid lymphomas). It was also expressed (more strongly) on tumor cells in 45 cases of diffuse large- cell lymphoma, most of which had originally been diagnosed as malignant histiocytosis or anaplastic carcinoma, because of their bizarre morphology. However, all of these cases lacked macrophage and epithelial antigens. Thirty-five cases expressed T cell-related antigens (associated in nine cases with the coexpression of B cell- related antigens), seven bore B cell-related antigens alone, and three were devoid of T and B cell markers. DNA hybridization with a JH specific probe showed a germline configuration in 11 cases of T cell phenotype, in two cases lacking T and B cell antigens, and in one case of mixed T/B phenotype, while rearrangement was found in two cases of clear B cell type and in one mixed T/B case. Expression of the Ki-1 antigen could be induced, together with interleukin 2 (IL 2) receptor, on normal lymphoid cells of both T and B cell type by exposure to phytohemagglutinin, human T leukemia viruses, Epstein-Barr virus, or Staphylococcus aureus. The results obtained indicate that Ki-1 antigen is an inducible lymphoid-associated molecule that identifies a group of hitherto poorly characterized normal and neoplastic large lymphoid cells. Tumors comprised solely of these cells show both morphological and immunological similarities to the neoplastic cells in Hodgkin's disease. This suggests that both disorders represent the neoplastic proliferation of activated lymphoid cells of either T cell or, less commonly, B cell origin. Disorders in which only a minority of cells express Ki-1 antigen (lymphomatoid papulosis, angio-immunoblastic lymphadenopathy, and certain T cell lymphomas) probably represent lesions in which only some of the abnormal cells have transformed into an “activation state.” In direct support of this view is the finding that the Ki-1 expression in these lesions is accompanied by the expression of HLA-DR and IL 2 receptors.

Activated RAS/BRAF oncogenes induce cellular senescence as a tumor-suppressive barrier in early cancer development, at least in part, via an oncogene-evoked DNA damage response (DDR). In contrast, Myc activation-although producing a DDR as well-is known to primarily elicit an apoptotic countermeasure. Using the Emu-myc transgenic mouse lymphoma model, we show here in vivo that apoptotic lymphoma cells activate macrophages to secrete transforming growth factor beta (TGF-beta) as a critical non-cell-autonomous inducer of cellular senescence. Accordingly, neutralization of TGF-beta action, like genetic inactivation of the senescence-related histone methyltransferase Suv39h1, significantly accelerates Myc-driven tumor development via cancellation of cellular senescence. These findings, recapitulated in human aggressive B cell lymphomas, demonstrate that tumor-prompted stroma-derived signals may limit tumorigenesis by feedback senescence induction.

Specimens of tissue from haemophilic synovium and articular cartilage were collected from 39 patients during reconstructive surgery. They were studied by histochemistry, electron microscopy and microprobe analysis. The detailed findings are presented and discussed. It is suggested that haemophilic arthropathy is the result of a number of mechanisms affecting the synovial lining which becomes progressively fibrotic and the hyaline cartilage which disintegrates and is eventually lost. Mechanical and chemical processes cause degeneration ofcells but enzymatic processes appear to be primarily responsible for the degradation of the matrix of the articular cartilage.

Hoping to improve the systems for identifying and classifying normal and malignant lymphoid subpopulations, frozen and paraffin sections of nonmalignant lymphoid tissue and of malignant lymphomas were immunostained for surface (S) and cytoplasmic antigens using the peroxidase-antiperoxidase method. Primary follicle cells and follicle mantle cells known to be part of the recirculating B-cell pool were found to be constantly Ia and C3 receptor (C3R) positive, mostly SIgM and SIgD positive and cytoplasmic immunoglobulin (CIg) negative. The light zone of germinal centers (GC), which is rich in centrocytes, contained a large number of T cells and showed the well-known intercellular Ig network pattern; the dark zone, containing densely packed centroblasts, was usually free of T cells, but was bordered ay a mantle-like accumulation of T cells. Usually only some of the GC cells were definitely positive for SIg and CIg of different classes. All cells reacted positively for Ia and C3R. In areas described by other authors as containing marginal zone cells, cells densely bearing SIgM and deficient in SIgD were detected. The immunoblasts of the hyperplastic plasma cell reaction usually contained CIg. Cells from chronic lymphoid leukemia sections that immunostained for SIgM and SIgD were interpreted as representing a neoplasm of recirculating B cells expressing SIgM and SIgD. The immunohistologic architecture of follicular centroblastic/centrocytic lymphoma showed a more or less close similarity to the organization of secondary follicles. Lymphomas whose cells resembled reactive centrocytes were strongly SIgM positive and SIgD negative or only weakly SIgD positive. CIg was demonstrable in nearly 90% of the lymphomas whose cells resembled centroblasts and in 70% of the lymphomas whose cells resembled immunoblasts of the plasma cell reaction. Finally, immunohistologic staining results from a T-zone lymphoma are presented, which confirm that this lymphoma was composed of a neoplastic T zone and a non-malignant B zone.