Effect of Ly 5 allotype on in vitro immune responses.

We have tested in vitro immune responses of several kinds to determine if Ly 5 allotype influences reactivity of murine splenocytes in processes thought to involve the T200 glycoprotein. Matings were established among C57BL/6J (B6) (Ly 5.1) and C57BL/6-Ly 5.2 (B6-Ly 5.2) congenic mice (both H-2b) to obtain sibling mice segregating for alloalleles of the Ly 5 system. F2 progeny of the three Ly 5 genotypes were tested for antibody-dependent cell-mediated cytotoxicity (ADCC), proliferation in allogeneic mixed lymphocyte culture (MLC), mitogen responsiveness, natural killer (NK) cell activity, and cytotoxic T-lymphocyte (CTL)-mediated cytotoxic activity. We observed that in Ly 5 segregant mice, higher CTL activity was associated with the Ly 5.2 type. No allotype effect was observed in MLC, mitogen responses, and NK cell-mediated cytolysis. In the parental and F1 animals, mice carrying the Ly 5.2 allele had significantly higher ADCC levels, though this effect was not seen in the segregants. Our results indicate that Ly 5 or some closely linked gene or genes influence CTL activity of murine splenocytes in vitro.