Assembly and secretion of pentameric IgM in a fusion between a nonsecreting B cell lymphoma and an IgG-secreting plasmacytoma.
A new immunoglobulin product has been obtained by hybridization of mouse cell lines arrested at different stages in B lymphocyte development. One line was shown to have the characteristics of an undifferentiated B cell that synthesizes monomeric IgM as a membrane receptor but does not express J chain. The second line was represent of a fully differentiated plasma cell synthesizing large amounts of IgG and J chain, but no IgM. Fusion of the two cell types yielded independent hybrid clones that secreted pentameric IgM, normally the first product of antigen-driven B cell differentiation. Analyses of the hybrid cells indicated that the IgM was expressed as a result of complementation between the synthetic capacities of the parental lines. The hybrid cells synthesized both monomeric IgM and J chain and assembled these components into a pentameric molecule with the expected stoichiometry of one J chain per five monomeric units. These findings provided further evidence that the induction of B cell differentiation includes a signal for de novo synthesis of the J chain. Moreover, the complementation achieved by this hybridization provides a system for identifying other intracellular events in B cell differentiation to IgM secretion.
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D005802:Genes, MHC Class II; D006822:Hybrid Cells / Q000276:immunology; D007074:Immunoglobulin G / Q000096:biosynthesis; D007144:Immunoglobulin J-Chains / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis* / Q000235:genetics; D008223:Lymphoma / Q000276:immunology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000276:immunology; D010954:Plasmacytoma / Q000276:immunology*
D007074:Immunoglobulin G; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M