Two different T-cell systems in humans, one of which is probably equivalent to Qa or Tla in mice.

Two different alloantigenic systems, expressed mainly on TG and TM lymphocytes and called TCA and TCB, respectively, are described. Alloantisera from parous women are absorbed with Epstein-Barr virus-transformed B cell lines from the husband of the serum producer to remove all anti HLA-A,B,C and DR antibodies. The absorbed sera are tested against a random panel and against lymphocytes from families. Family studies indicate that the TCA system might be encoded by a gene linked to HLA and located on the telomeric side of HLA-A. The total lod scores for the material of 15 informative families is +3.301 at a recombination fraction of 15%. Furthermore we can show that the TCA molecule is associated with beta 2-microglobulin by blocking with turkey anti-beta 2 microglobulin. The antigens are dimers of peptides with a molecular weight of approximately equal to 42,000 daltons and 12,000 daltons, respectively. This implies that TCA might be equivalent to either Qa or Tla in the mouse. For the TCB system no evidence is found for linkage with any known genetic marker. Only in random population studies is an association seen between TCB and Gm.