Gene conversion may be responsible for the generation of the alloreactive repertoire.

Meiotic gene conversion in the major histocompatibility complex (MHC) appears to be involved in the generation of MHC polymorphism. Here the authors suggest that mitotic gene conversion of MHC may generate somatic variants which sensitize the immune system. This could lead to an MHC-skewed repertoire with a high background alloreactive potential crossreacting with foreign antigens in the context of self MHC. Allodeterminant-bearing autologous cells may be deleted by the immune cells, thereby maintaining the observed genotype/phenotype correlation.