In vivo mutations at the H-2 locus in mouse lymphocytes

An experimental system has been developed to study in vivo autosomal mutations in murine splenic lymphocytes. Mutant lymphocytes were isolated by immunocytotoxicity using monoclonal antibodies directed against the k and d alleles of the K and D H-2 histocompatibility loci and were enumerated using limiting-dilution cloning. Genomic allele loss in mutant clones was detected using allele-specific primers in a polymerase chain reaction. Mutant clones were classified on the basis of phenotypic and genotypic criteria into "no change", deletion or recombination mutants. The geometric mean mutation frequency in 102 mice was 2.42 × 10^-4. Detailed phenotypic and genotypic study of 87 mutant clones from 4 mice revealed "no change" mutants in 83%, mutants due to deletion in 7% and mutants due to recombination in 7%. Anomalous results were obtained in 3% of mutant clones. The development of an animal model for study of in vivo mutations at an autosomal locus will further advance study of mutations, particularly those involving chromosomal changes such as mitotic recombination.