H-2 control of expression of an idiotype shared by normal B cells and a B-cell lymphoma.

The spleens of normal B10.H-2aH-4bp/Wts (2a4b) mice contain cells which, in response to mitogen stimulation, secrete hemolytic antibody specific for a determinant present on both sheep and bromelain-treated mouse erythrocytes. These cells were found to be Ly-1 positive. Approximately 50% of these cells bear surface immunoglobulin (sIg) with the same idiotype as the sIg of a 2a4b-derived B-cell lymphoma, CH12. Backcross analysis revealed H-2 control of the frequency of the idiotype-positive B cell. The regulatory gene did not correlate with the Igh-1 allotype, and analysis of 22 inbred mouse strains mapped the gene to the I-E subregion. Surprisingly, only strains homozygous for Ek alpha expressed the idiotype, and expression was a recessive trait. Possible mechanisms for this control of idiotype expression and its relation to lymphomagenesis are discussed.