Diverse effects of bursectomy on humoral immune responses in the chicken.

Chickens bursectomized hormonally or surgically at various ages in embryonic to postembryonic lives were immunized with a mixture of antigens, and the antibodies produced titrated. immune responses to Salmonella pullorum (SP), Brucella abortus (BA). Staphylococcus aureus (Staph) and ovalbumin (OA) were more markedly suppressed by the bursal deprivation than those to heterogenous erythrocytes, viruses and such bacteria as Pasteurella multocida (PM) and Escherichia coli B. The immune response to bovine serum albumin (BSA) was on a level between the two groups. Hormonal bursectomy in embryonic life permitted chickens immunized with sheep red blood cells (SRBC) to produce antibody of the IgM type but not of the IgG type. In surgically bursectomized chickens IgG but not IgM production was inhibited. Chickens hormonally bursectomized on the third day of egg incubation produced IgM to a level higher than the normal chickens in contrast with the suppressed IgG production. Such diversity in the bursal influences on antibody responses was discussed in relation to ontogeny of the humoral immune system.