Column selection of antigenic variants from tumors. YAC (Moloney) lymphoma variants with reduced antigen expression

Serial pretreatment of YAC lymphoma cells with anti H-2^a serum and anti-Ig column selection to remove cells with high surface H-2 concentration, followed by intermittent transfer into mice has led to the establishment of two variant sublines with low H-2^a antigen expression and only a slightly reduced Moloney virus-determined cell surface antigen (MCSA) expression compared to the original YAC line. Both sublines had an increased number of chomosomes with a modal number of 62 and 57, as compared to 39 in YAC. In contrast to YAC, the variants were freely homotransplantable across the H-2 barrier. They also resisted the rejection response of YAC-preimmunized semisyngeneic mice. Parallel selection against MCSA resulted in a variant with reduced MCSA, but unchanged H-2^a expression and karyotype. This subline failed to grow across the allograft barrier, and showed only a slightly increased ability to grow in preimmunized semisyngeneic mice. These results suggest that H-2 expression may play an important role in the ability of antigenic tumor cells to be rejected in specifically preimmunized, genetically compatible recipients.