Studies on J chain and binding site for secretory component in circulating human B cells.
Lymphocyte-enriched mononuclear cell fractions were obtained from the peripheral blood of four healthy young adults. Living B cells with membrane immunoglobulin (Ig) were studied by immunofluorescence to reveal exposed J-chain determinants or surface affinity for the secretory component (SC). Alcohol-fixed cell smears were similarly studied with and without prior denaturation in acid urea. It was concluded that J chain-containing polymeric Ig of endogenous origin is generally not present on the surface of circulating B cells. If occasional cells bear IgM or IgA polymers rather than monomers, their SC-binding site must be concealed to a degree that it is not functional. Affinity for SC is therefore unlikely to be involved in a selective homing of IgM- and IgA-immunocyte precursors from peripheral blood to glandular regions.
D000328:Adult; D000936:Antigen-Antibody Complex; D001402:B-Lymphocytes / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology; D000939:Epitopes; D006801:Humans; D007070:Immunoglobulin A; D007128:Immunoglobulin Fragments; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D012635:Secretory Component
D000936:Antigen-Antibody Complex; D000939:Epitopes; D007070:Immunoglobulin A; D007128:Immunoglobulin Fragments; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D012635:Secretory Component