Isolation of 7S IgM and kappa chains from the surface membrane of tissue culture cells derived from a Burkitt lymphoma.

By homogenization or by freezing and thawing, mu and kappa structures were liberated from the surface of Daudi cells, a Burkitt lymphoma-derived culture line. After removal of the membranes and particles by ultracentrifugation, approximately one-third of the immunoglobulin structures remained in the supernatant. By density gradient ultracentrifugation and gel filtration on Sephadex G-200, it was established that the supernatant contained 7S IgM molecules and free kappa chains. Also, kappa structures were in excess on the sedimented membranes as compared with mu structures. The immunoglobulins were detected and quantitated by inhibition of passive hemagglutination.