Complementation between a gene of the I-E subregion and a non-H-2 gene in the class-specific suppression of IgG2a antibody to sheep erythrocytes.

A low level of IgG2a antibodies is observed in B10 mice after primary immunization with SRBC. Analysis of the response in different H-2b mice and among B10 animals with different H-2 haplotypes reveals that this selective isotype deficiency is under the control of at least two genes: a background gene and an H-2-linked gene. Responses of H-2 recombinant B10 strains map the H-2-linked gene to the 1-E subregion. Evidence is presented for complementation between H-2 and non-H-2 genes in the determination of the low responder phenotype. Low responsiveness appears to be inherited as a dominant trait. Possible functions of the two series of genes are discussed in relation to suppressor mechanisms.