Secretion of human immunoglobulins by mouse myeloma x Daudi somatic cell hybrids.

Somatic cell hybrids between nonproducer mouse myeloma cells and Burkitt lymphoma-derived Daudi cells that do not secrete human immunoglobulin chains secrete human IgM. The 33 000 dalton protein (P33) is also secreted by the hybrids as part of the IgM molecule. Since P33 and kappa chains cosegregate in all primary hybrid clones and subclones, it is concluded that they are coded for by the same human chromosome 2. The fact that both P33 and kappa' chains are immunoprecipitated by specific anti-human kappa chain antisera, and that both P33 and kappa' bands disappear and a single band immunoprecipitable by an anti-human kappa chain antiserum appears in tunicamycin-treated hybrid cells, suggest that they are differently glycosylated forms of the same polypeptide.