Genetics of mouse antibodies. II. Recombination between VH genes and allotype

Abstract

The BAB/14 (BALB/c.C57BL/Ka‐Ig‐1^b/Hz) congenic mouse strain was found to respond to (4‐hydroxy‐3‐nitrophenyl)acetyl (NP)‐chicken globulin immunization with nonheteroclitic anti‐NP antibodies as does the BALB/c inbred partner strain. This is in contrast to the heteroclitic anti‐NP response of the C57BL/Ka allotype donor strain and indicates that the allotype linked V_H‐NP gene was inherited with the V_H‐DEX gene from BALB/c rather than with the allotype genes from C57BL/Ka. This verifies the interpretation of BAB/14 as an immunoglobulin gene recombinant. Two recombinants between V_H‐DEX and Ig‐1 allotype genes have been found among 554 chromosomes tested yielding a recombination frequency of 0.4%. Analysis of the BAB/14 recombinant showed that this crossover occurred between V_H genes implying that V_H genes and C_H genes are not organized in separate clusters separated by a large spacer region but are contiguous. Analysis of the recombination frequencies indicates that the total number of V_H genes must be at least 50.