Suppression of VH, C gamma and C mu gene products in rabbits by maternal immunization against IgM allotype and detection of somatic recombinant molecules in these animals

Allotype suppression in the chicken. V. Abnormal isotype ratios of chronically suppressed IgM and IgG allotypes

Chronic allotype suppression was generated in M-1 (C mu), G-1 (C gamma) heterozygous B14 line chickens either by embryonal injection or by maternal transfer of anti-M-1b allotype antibodies. Using a sensitive radioimmunoassay to detect the suppressed IgM-1b, a striking disparity was observed between the degree of suppression of the IgM-1b allotype and that of the genetically linked IgG-1i allotype. The amount of suppressed IgM-1b ranged between 0.2 and 3% of total serum IgM in chronically suppressed birds. The levels of the genetically linked IgG-1i, however, comprised 5 to 25% of total serum IgG in such birds. The allotypes measured in suppressed chickens were qualitatively identical to those in normal, nonsuppressed birds by serological criteria. These results are discussed within the context of isotype regulation in the chicken.

Production of IgG-specific auto-anti-allotypes in b4.2-suppressed rabbits

Rabbits were completely suppressed for kappa chain allotype b4.2, and autoantibodies against b4.1 or b4.2 could be raised in 2 out of 3 animals. The animal immunized with b4.1 produced anti-b4 and anti-Ms3, two activities which have never as yet been found together in one antiserum. Both autoantisera lacked the capacity to bind b4.2-IgM, whereas they precipitated 4.2-IgG very well. In one animal, anti-b4 IgM activity appeared after the sixth immunization, at the age of 14 months. Allotype suppression was maintained in both rabbits till the end of their lives whereas all control animals recovered within 6 months. The autoantisera which were specific for b4 IgG could not induce suppression in vivo. However, specific inhibition of b4 IgG secretion was observed in vitro.

Rabbit heavy chain haplotypes--allotypic determinants expressed by VH-CH recombinants

This report summarizes our current understanding of the heavy chain haplotypes found in our laboratories' rabbits. Independently derived data from several laboratories have been synthesizes into a consistent picture of the linked inheritance of allotypic markers found on the different heavy chain classes and subclasses of rabbit immunoglobulins in pedigreed rabbits, including the families of three apparent VH-CH recombinants. In one recombinant, the entire group of CH markers (C mu, C gamma, and C alpha) recombined with the set of VH. Although in the other two recombinants all CH markers may also have recombined as a group, in one of these only IgG and IgA CH genes were informative; in the other recombinant, only the IgG allotypes were informative. Some allotypic determinants found on IgM molecules ("conformational") appear only when a specific variable region allotype (VHa) is combined with a specific mu constant region allotype (C mu). New combinations of VHa and C mu allotypes were generated in two of the genetic recombinants and led to new "conformational" determinants. The gains and losses observed lend support to the hypothesis that the determinants result from conformations generated by the combination of allotype-specific VH and C mu protein sequences. Conceivably, DNA events that join VH to diversity (D)- and joining (J)-coding sequences or mRNA processing events that splice J to C mu could be involved in generating the sequences that form allotype-specific determinants.

An increase in the number of recombinant molecules and other effects of the simultaneous allotype suppression of trans-chromosomal a VH and n Cmu Ig gene products

The concomitant effects of trans-chromosomal allotype suppression of both an a VH and an n Cmu locus allotype in multiheterozygous rabbits were investigated. For example of the expression of the a2 VH and n81 Cmu allotypes were suppressed in a multiheterozygous rabbit having the a1 chi-y-n81de12,15f73g74/a2 chi 32y33n80de12.14f69g77 genotype. This trans-chromosomal allotype suppression led to the concomitant suppression of other CH allotypes in the same parental haplotype as the suppressed-n81 allotype (i.e. the e15, f73 and g74 allotype) and the partial suppression of the a1 VH allotype (from the normal level of 70% of the total Ig to 10%), and also led to compensation by other VH allotypes from the same parental haplotype as the suppressed-a2 allotype (i.e. the x32 and y33 allotypes). The x32 and y33 allotypes were expressed on Ig molecules with the CH allotypes coded by the same haplotype (i.e. the cis molecules). In a further analysis of the IgG molecules having the partially-suppressed-a1 allotype, one-half (5%) of these molecules were trans-chromosomal recombinant molecules (i.e. a1e14 IgG) and the other half (5%) were cis-chromosomal molecules (i.e. a1e15 IgG). The trans-chromosomal a1e14 IgG molecules probably were derived from the expansion of a limited number of lymphoid clones that normally produce only 1.5% trans-chromosomal recombinant molecules. The cis-chromosomal a1e15 IgG molecules were probably derived either from lymphoid clones that survived the suppression by the anti-n81 Ab, or from lymphoid clones that bore a different subclass of IgM (i.e. n-negative IgM).