MOLECULAR COMPARISON OF CULTURED HYBRIDOMA CELLS THAT SWITCH ISOTYPESAT HIGH AND LOW RATES

We have previously reported the isolation of variants from the 36.65 a nd PC1.4.1 hybridoma cell lines that spontaneously switch from gamma 1 to gamma 2a and gamma 2b at high and low rates. In order to further c haracterize the phenotype of these variants, we have now investigated the production of germline transcripts and methylation which are two o f the molecular correlates of isotype switching. While some of the cor relations that exist in normal cells were present in some of the clona l variants, others were not. However; the higher switching variants of both cell lines had higher recombinational activity as measured with a shuttle vector: The distinct phenotypic characteristics of each cell line provide art opportunity to dissect the roles of individual molec ular events in the process of isotype switching.