Confirmation of the assignment of genes for human immunoglobulin heavy chains to chromosome 14 by analysis of Ig synthesis by man‐mouse hybridomas

Hybridomas were produced by fusing the NS1 mouse myeloma line, which does not produce mouse heavy chain Ig, with human peripheral B lymphocytes from a normal individual. Two vigorously growing colonies from this fusion were found to secrete human Ig heavy chains and were recloned. Two secondary clones, which secreted human chains, were again recloned. Among the tertiary clones, two were identified which produced intracellular human Ig chains, but did not secrete immunoglobulin. These tertiary clones were recloned, generating 6 quaternary clones which failed to produce human Ig heavy chains, and 15 quaternary clones which produced intracellular Ig chains. Hybrid clones from each successive subcloning were examined for their human chromosomal content and only those clones which were found to be individually chromosomally distinct, a total of 56 clones in all, were used to analyze the segregation of human chromosomes and human Ig heavy chain synthesis. Results of this study indicate concordant segregation of human Ig heavy chain synthesis and chromosome 14. These studies therefore confirm the previous assignment by C. M. Croce et al. (Proc. Natl. Acad. Sci. USA 1979. 76: 3416) of the genes for human Ig heavy chains to chromosome 14.