title: Independent regulation of IgM, IgD, and Ia antigen expression in cultured immature B lymphocytes.
abstract: Long-term cultured bone marrow cells were characterized with respect to a number of B and pre-B cell markers. Cells expressing ThB, B-220, and IgM were found within cultures set up according to the procedure of Whitlock and Witte. This culture system was modified by placing sorted pre-B cells (ThB+, IgM-) from bone marrow in culture with previously-established bone marrow adherent layers. These cultures commenced growth without the lag associated with the Whitlock cultures. These cultured nonadherent cells show a high frequency of IgM+ cells, but do not express either IgD or Ia, and we refer to them as immature B cells. Cells with a similar phenotype (IgM+, Ia-, IgD-) are found within the spleens of young but not adult mice. The phorbol ester PMA induces expression of IgD on the cultured immature B cells, but has no effect on Ia expression. This suggests that the processing of H chain RNA transcripts may be affected by protein kinase C. These results demonstrate that the appearance of IgM, IgD, and Ia are independently controlled in long-term cultured B-lineage cells.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D007072:Immunoglobulin D / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D010703:Phorbol Esters / Q000494:pharmacology
chemical_list: D000949:Histocompatibility Antigens Class II; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D010703:Phorbol Esters