title: Lymphocyte surface immunoglobulins.
abstract: Immunoglobulins have been isolated from the surface of B (bone marrow-derived) and T (thymus-derived) lymphocytes. Two types of membrane immunoglobulin occur on B lymphocytes; one type resembles the 200,000-dalton subunit of IgM, the second possesses a heavy chain electrophoretically distinct from mu chain and does not correspond to any of the known classes of mouse immunoglobulins. It might correspond to human sigma chain. T lymphocytes possess only one type of surface immunoglobulin. This molecule has a mass of approximately 200,000 daltons and contains light chains and heavy chains similar to, but not identical to, mu chains. Evidence now exists that surface IgM-like immunoglobulins of B lymphocytes and T lymphocytes activated to certain antigens can bind specifically to antigen. These observations suggest that surface immunoglobulin functions as a receptor for antigen on B cells and at least on some T cells. The mechanisms by which combination of antigen with surface immunoglobulin initiate differentiation remain to be determined.
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology*; D001666:Binding Sites, Antibody; D005075:Biological Evolution; D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis; D008954:Models, Biological; D008970:Molecular Weight; D011487:Protein Conformation; D011947:Receptors, Antigen, B-Cell / Q000032:analysis* / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell