Studies on mouse hybridomas secreting IgM or IgA antibodies to α(1→6)-linked dextran

Abstract

Twelve mouse hybridomas secreting antibodies to dextran B512, identified by replica immunoadsorption screening of 100,000 immobilized hybridoma clones, were obtained. Among 11 hybridomas of BALB/c origin seven produce IgM and four produce IgA. One hybridoma of C57BL/6 origin synthesizes IgA. A κ light chain is synthesized by each of the 12 hybridomas in addition to the nonspecific κ light chain of the parent myeloma. The heavy chain is shown to associate preferentially with the specific (spleen cell derived) light chain. All hybridoma antibodies were purified from ascites by precipitation with dextran B512, followed by subsequent digestion of the dextran with dextranase. Although all the specific light chains migrate identically in SDS gels under reducing conditions, variations in migration are noticed among the heavy chains. Differences in migration among the IgA monomers and among the IgA polymers are seen on nondenaturing polyacrylamide gels. Densitometer scans of such gels show that more than 50% of the IgA hybridoma antibodies are in polymeric form. Implications of the preferential association of heavy chain with specific light chain, and of the size differences among the heavy chains for the generation of antibody specificity and diversity are discussed.