Allotype suppression at the CHn locus of IgM in heterozygous rabbits with concomitant suppression at the VHa locus of all Ig classes.

Doubly heterozygous offspring, malen83alpha1/femalen82alpha2 or malen81alpha1/femalen82alpha2, of doubly homozygous dams, n82alpha2/n82alpha2, were injected neonatally with anti-n83 or anti-n81 antibody directed to the paternal n locus allotype. In each injected rabbit, the paternal n83 or n81 allotypes were suppressed and increased amounts of the maternal n82 allotype accounted for almost all of the serum IgM. This is the first report of allotype suppression in the rabbit mediated by antibody directed toward the CH region of any Ig class. A concomitant decrease in the paternal a1 Ig allotype and a compensatory increase in the maternal a2 allotype were also found. This finding supports the concept that IgM-bearing cells are the precursors of IgG-secreting cells.