Kinetics of escape from suppression of Ig heavy chain allotypes in multiheterozygous rabbits

Three rabbits of genotype a1n81f73g74/a2n82f71g75 which had been injected at birth with anti-a l (VH) antiserum and which were previously shown to be suppressed for the paternal allotypes a 1, n81, f73 and g74 at 8 weeks of age, were monitored over a 2-year period for the concentration of suppressed and nonsuppressed allotypes in their sera. In all three suppressed animals, the f73 (C alpha) and g 74 (C alpha) allotypes were expressed again at a much greater rate than the a1 (VH) and n81 (C mu) allotypes. In one suppressed animal, the a l (VH) allotype was re-expressed at a much greater rate than the n81 (C mu) allotype and reflected primarily the reappearance of a l IgG. Thus, the escape from allotype suppression in this animal was in the order IgA, IgG, IgM which is the reverse of the order of appearance of these Ig classes during ontogeny. While the al(VH) and n81 (C mu) allotyes remained suppressed, the f73 (C alpha) and g74 (C alpha) allotypes were re-expressed to the same concentration as in the unsuppressed controls, and no compensatory decrease of the f71 and g75 allotypes occurred. During the re-expression of the f73 and g74 allotypes, the ratio of the concentrations of f73/g74 remained approximately constant.