GENE-MAPPING IN A MURINE CELL-LINE BY IMMUNOSELECTION WITH CYTOTOXIC T-LYMPHOCYTES

Minor histocompatibility (II) loci encode alloantigens that are recogn ized by cytotoxic T (Tc) lymphocytes. A (C57BL/10 X 129)F-1-derived tr ansformed lymphocyte cell line was immunoselected in vitro with cloned Tc cells that were specific for H-3a(a), a Chromosome 2-encoded minor H antigen. This cell line is heterozygous at H-3a (former symbol, Cd- 1) and other loci. Three groups of antigen-loss variants were identifi ed. One group contained mutations affecting only the antigen-encoding gene. Another group probably arose through a single homologous interch romosomal exchange, resulting in extensive regions of loss of heterozy gosity (LOH). The third group of variants contained an interstitial LO H, one of which was shown to be a significant deletion. Several deleti on boundaries were identified, one of which ordered the closely linked H-3a and beta(2)-microglobulin (B2m) genes. We suggest that Tc immuno selection against minor H antigens is a promising approach for targeti ng negative selection to specified chromosomal regions and can provide high-resolution genetic map information. (C) 1994 Academic Press, Inc .