Studies on rabbit lymphocytes in vitro. IV. Blast transformation of the lymphocytes from newborn rabbits induced by antiallotype serum to a paternal IgG allotype not present in the serum of the lymphocyte donors.

Lymphocytes from the peripheral blood of newborn rabbits heterozygous for IgG allotypes As4 and As5, or As5 and As6, obtained at an age when only the maternal allotypic determinants are detectable in the serum, may be stimulated in vitro to transform into "blast" cells with antiallotype sera directed against the determinants contolled both by the maternal and by the paternal chromosomes. This result rules out the possibility that allotypic specificity is conferred upon lymphocytes by environmental IgG and suggests that the lymphocytes of newborn rabbits have the potential to synthesize IgG determinants either in the form of intact IgG molecules or constituent polypeptide chains.