Allotype suppression in the chicken. I. Generation of chronic suppression in heterozygous but not in homozygous chickens.

The injection of antibody directed against either the IgM-1 a or IgM-1 b allotype into heterozygous (M-l^a/M-l^b, G-l^g/G-lⁱ) B 14-line chickens produced suppression of the relevant IgM-1 and genetically linked IgG-1 allotypes in their serum, as quantitated by single radial immunodiffusion. Suppression of the IgM-1 and IgG-1 allotypes was associated with a compensatory increase in the alternative IgM-1 and IgG-1 serum allotype levels. This suppression was induced (a) by passive injection of anti-allotype antiserum into 13-day-old embryonal or neonatal recipients, or (b) by egg yolktransmitted antibody in chickens hatched from homozygous B 14 A (M-l^a, G-l^g) hens immunized against the IgM-l b of the homozygous B14C (M-l^b, G-lⁱ) rooster. Heterozygous chickens injected embryonally with anti-allotype antiserum were profoundly suppressed for at least 16 weeks after hatching, while neonatally injected chickens showed a gradual recovery of both IgM-1 and IgG-1 allotypes over the same period. Suppression of the IgM-1 b allotype could be induced in heterozygotes which had inherited the M-l^b allele either maternally or paternally. However, no suppression of either IgM-1 or IgG-1 levels could be detected in homozygous chickens injected with the relevant anti-allotype antiserum. Hence, allotype suppression only occurred in M-1 heterozygous chickens which had an alternative source of B cells available. The involvement of a B cell surveillance mechanism in allotype suppression is postulated and the possible role of suppressor cells is discussed.