Relationships between beta2-microglobulin and alloantigens coded for by the major histocompatibility complexes of the rabbit and the guinea pig.

Treatment of rabbit and guinea pig lymphocytes with Fab' fragments of anti-beta2-microglobulin completely inhibited the cytotoxic effects of alloantisera to RLA or GPLA antigens, respectively. Aggregation of beta2-microglobulin on the lymphocyte surface by successive incubations with goat anti-beta2-microglobulin on the lymphocyte surface by successive incubations with goat anti-beta2-microglobulin and F(ab')2 fragments of rabbit anti-goat IgG also made rabbit lymphocytes resistant to lysis by anti-RLA, and guinea pig lymphocytes resistant to lysis by anti-RLA, and guinea pig lymphocytes resistant to lysis by anti-GPLA. The two kinds of pretreatment of guinea pig lymphocytes did not affect the cytotoxicity of antisera directed against guinea pig Ia antigens. These results in conjunction with previous findings in the mouse and in man suggest that beta2-microglobulin on the lymphocyte surface in mammals is generally associated with major serologically defined histocompatibility antigens but not with I-region-associated antigens.