Heterogeneity of immunoglobulin-associated molecules on human B cells identified by monoclonal antibodies.

T Nakamura, H Kubagawa… - Proceedings of the …, 1992 - National Acad Sciences
T Nakamura, H Kubagawa, MD Cooper
Proceedings of the National Academy of Sciences, 1992National Acad Sciences
Two covalently linked transmembrane molecules, encoded in mice by the mb-1 and B29
genes, have been defined as integral components of the antibody receptor units expressed
on B cells. We have produced monoclonal antibodies against an exposed extracellular
epitope on the putative human equivalent of the mouse B29 product. These antibodies, CB3-
1 and-2, were used to show that cytoplasmic expression of this molecule begins in human
pro-B cells (terminal deoxynucleotidyltransferase-positive, mu chain-negative), whereas …
Two covalently linked transmembrane molecules, encoded in mice by the mb-1 and B29 genes, have been defined as integral components of the antibody receptor units expressed on B cells. We have produced monoclonal antibodies against an exposed extracellular epitope on the putative human equivalent of the mouse B29 product. These antibodies, CB3-1 and -2, were used to show that cytoplasmic expression of this molecule begins in human pro-B cells (terminal deoxynucleotidyltransferase-positive, mu chain-negative), whereas surface expression coincides strictly with surface immunoglobulin expression of all isotypes. Immunochemical analysis of the human immunoglobulin-associated molecules revealed greater molecular heterogeneity than has been noted for the murine analogues. This molecular heterogeneity of immunoglobulin-associated molecules varied as a function of differentiation stage and the immunoglobulin isotypes expressed by B-lineage cells. Our data support the hypothesis that biochemical heterogeneity of the surface immunoglobulin-associated molecules may contribute to the variability in biological effects of antigen receptor crosslinkage on B cells of different maturational stages. Because the CB3 antibodies are capable of down-modulating the antigen receptors on all B cells, they may prove therapeutically useful as universal B-cell suppressants.
National Acad Sciences