Allogeneic antibody response in cattle.

Antibody responses following immunization with allogeneic bovine lymphocytes, goose red blood cells (GRBC), and ovalbumin (given IV) were studied in 20 heifers. Antibody to GRBC was detectable by 4 to 9 days in all heifers and followed the characteristic pattern of a low-titer primary response which was predominantly immunoglobulin (Ig) M, whereas a high titer IgG secondary response was observed. The dose of ovalbumin used failed to elicit a detectable antibody response. An immune response to allogeneic lymphocytes was observed, but it differed from the GRBC response. Cytotoxic antibody directed against lymphocytes was detectable by day 14 in 5 of the heifers. Five others responded by days 17 to 24 after secondary immunization. The responses were of low titer and predominantly IgM, after both primary and secondary immunizations. The time of antibody appearance and titers varied between heifers and was not dependent on differences at the major histocompatibility complex (BoLA) between heifers and immunizing lymphocytes. Cytotoxic antibody reacted with both B and T lymphocytes and appeared to recognize the serologically defined BoLA antigens. Noncytotoxic alloantibody was detected in the serum of 1 heifer and appeared to be directed against a subpopulation of lymphocytes, possibly those bearing Ia-like antigens.