A new antigen identified by the monoclonal antibody UCHB 1 delivers a costimulatory signal to a subset of human B cells.
A novel anti-B cell monoclonal antibody UCHB1 is described which detects an antigen present on a selected subpopulation of both normal and leukemic B cells. Approximately 20% of normal tonsil and peripheral blood (PB) B cells are UCHB 1+ and the majority of B cells from all cases of prolymphocytic leukemia (PLL) tested, together with a low, variable percentage of PB B cells from non-Hodgkin's lymphoma patients with centroblastic centrocytic leukemia also express this antigen. Chronic lymphocytic leukemia and hairy cell leukemia B cells, pre-B acute lymphoblastic leukemia and Epstein-Barr virus transformed cell lines all lack UCHB 1 positivity as do all non-B lineage leukocytes and cell lines so far tested. In tonsil sections UCHB 1 staining is almost completely confined to surface IgM+ mantle zone lymphocytes and follicular dendritic cells, but not B cells, within the germinal centers. UCHB 1 can induce a rise in the level of intracellular free calcium ([Ca2+]i) in PLL B cells and low concentrations of monoclonal antibody can result in the entry of these cells into cell cycle in the absence of additional factors. The proliferative effect of UCHB 1 is greatly enhanced in the presence of Staphylococcus aureus Cowan and, to a lesser extent, phorbol ester. A similar costimulatory effect is exerted on a proportion of normal tonsil B cells although here, despite inducing a rise in [Ca2+]i, UCHB 1 alone does not cause cells to proliferate. UCHB 1 may well prove to be a useful antibody both to distinguish between different B cell leukemias and to study the phenotype and function of leukemic and normal B cell subpopulations.
Armitage
R J
RJ
I.C.R.F. Human Tumour Immunology Group, U.C.H. Medical School, London, GB.
Rowe
D J
DJ
Beverly
P C
PC
D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology*; D000937:Antigen-Antibody Reactions; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis* / Q000276:immunology; D001402:B-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002453:Cell Cycle; D002460:Cell Line; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D014066:Palatine Tonsil / Q000166:cytology; D010641:Phenotype; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D011947:Receptors, Antigen, B-Cell; D002118:Calcium; D013936:Thymidine