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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‐la/M‐lb, G‐lg/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‐la, G‐lg) hens immunized against the IgM‐l b of the homozygous B14C (M‐lb, 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‐lb 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.