POSSIBLE SOMATIC CELL MATING IN TWIN CATTLE WITH ERYTHROCYTE MOSAICISM

Abstract

The proportions of the 2 antigenic types of cells in cattle chimeric twins may change with time. The direction and magnitude of change is usually the same in both members of a pair. Consequently, they are not thought to be the result of an abrogation of immunologic tolerance. One chimeric twin was found at 3 years of age whose blood contained 2 antigenic types: 10% representing his own genotype and 90% the genotype of his co-twin. When the blood of this chimera was retested at 8 years of age, 3 blood types were found: the 2 "parental" types, each representing 2%, and a "hybrid" type representing 96% of the cell population. It is postulated that the "hybrid" cell type resultedfrom "mating" between the 2 hematopoietic tissues in the chimeric mixture and that the hybrid type had a distinct selective advantage.