title: Differential signal requirement for upregulation of HLA-class II molecules in human lymphoma B cells.
abstract: HLA-class II molecules can be induced in low-grade non-Hodgkin B lymphoma cells by either membrane IgM cross-linking or phorbolester stimulation. The ability of phorbolesters to substitute for anti-IgM antibodies in the activation of normal and malignant human B cells has been taken as evidence for the involvement of protein kinase C (PKC) in signals transduced through membrane IgM receptors (mIgR). Here we report on freshly isolated lymphoma B cells from different patients; the cells show a distinct regulation of HLA-class II expression. In certain lymphoma cases phorbol-myristate-acetate (PMA) not only fails to up-regulate HLA-class II molecules but also inhibits anti-IgM or interleukin-4 induced class II expression. This negative signal induced by PMA seems to operate specifically in HLA-class II regulation because PMA can induce other anti-IgM mediated events like blast transformation and induction of IL-4 responsiveness at the same time. Therefore these cells support the concept of functional heterogeneity in low-grade non-Hodgkin lymphoma and may represent a differentiation stage where anti-IgM antibodies and phorbolesters influence the regulation of HLA-class II expression in a contrary direction.
authors.affiliation: Medizinische Poliklinik, University of Würzburg, Germany.
authors.forename: H P
authors.initials: HP
authors.lastname: Tony
authors.forename: A
authors.initials: A
authors.lastname: Brückner
authors.forename: M
authors.initials: M
authors.lastname: Wilhelm
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000502:physiology; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology; D016393:Lymphoma, B-Cell / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D011493:Protein Kinase C / Q000502:physiology; D011961:Receptors, Fc / Q000378:metabolism / Q000502:physiology; D017455:Receptors, IgE / Q000032:analysis; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation / Q000235:genetics* / Q000502:physiology
chemical_list: D000906:Antibodies; D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M; D011961:Receptors, Fc; D017455:Receptors, IgE; C035311:immunoglobulin M receptor; D015847:Interleukin-4; D000001:Calcimycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate