EVIDENCE FOR GENE DOSE EFFECT OF HI (AgB) DETERMINED ANTIGENS IN RAT MIXED LYMPHOCYTE CULTURE

The stimulation obtained in mixed lymphocyte cultures (MLC) with mitomycin treated target cells of a different HI (AgB) type has been investigated for the possible effect of gene dosage. Almost invariably it was found that target cells carrying two rather than one chromosome with a particular foreign HI allele caused a significantly higher degree of stimulation. This fact pertained to the comparison of target cells from homozygous pure strain and the Fl hybrid. It also holds for the comparison of F2 hybrids homozygous and heterozygous respectively for a given foreign HI allele (3). The greater degree of stimulation by homozygous target cells was manifested during the entire culture period and was found to exist over a wide range of target cell concentrations. These findings contrast with other published data when no evidence for a gene dose effect of HI determined antigens was found. The possible reasons for this discrepancy are discussed.