THE EFFECT OF CARRIER AND CARRIER PRIMING ON THE KINETICS AND PATTERNOF SOMATIC MUTATION IN THE V-CHI-OX1 GENE

Priming mice with a chicken gamma globulin (CGG) carrier protein signi ficantly accelerated the onset of somatic mutation in the VHOx1 gene w hen the mice were subsequently immunized with 2-phenyl-5-oxazolone (ph Ox) coupled to CGG. The first mutations were already detected 7 days a fter immunization, while in the true primary response, they are not ap parent until day 10. It was also found that comparing the mutation pat tern of VHOx1 genes from hybridomas derived after immunization with ph Ox coupled to different carriers revealed quite distinct patterns of s omatic mutation. Analysis of hybridoma sequences from the primary immu ne response to phOx-ovalbumin showed that the codons for Ser(29), Ser( 31) and Lys(45) were hot-spots for somatic mutation. Thus, the frequen cy and pattern of somatic mutations in the VrHOx1 gene depends on the available T cell help as well as on the complex structure of the immun izing antigen.