SIMULTANEOUS EXPRESSION OF KAPPA-LIGHT-CHAINS AND LAMBDA-LIGHT-CHAINSIN A MURINE IGG(3) ANTI-CRYPTOCOCCUS NEOFORMANS HYBRIDOMA CELL-LINE

Allelic exclusion normally results in the expression of only one light and one heavy chain gene. However, some hybridomas have been reported to express two different heavy chain genes. Here we report that the I gG(3) hybridoma 4H3.C8B expresses both kappa and lambda light chains. 4H3.C8B was originally recovered by screening for antibody binding to Cryptococcus neoformans polysaccharide antigen and characterized as ga mma 3 lambda. The gamma 3 lambda but not the gamma 3 kappa binds to po lysaccharide antigen. Some of the antibody molecules were heterodimers composed of both lambda and kappa. IgG(1) and IgG(2b) isotype switch variants were identified and isolated by the technique of sib selectio n, using the ELISA spot assay. Like the parent IgG(3) line, the switch variants continued to express both kappa and lambda light chains but only the lambda-containing antibodies bound to the antigen. Our experi ence suggests that hybridomas recovered by assays that are antigen dep endent should also be tested for the expression of other isotypes and light chains in a non-antigen-binding immunoassay.