Identification of Four MLC‐Specificities in the Dog

Typing for MLC determinants was done in 82 beagles of five different colonies using reference cells which could be shown by family analysis to be homozygous for both the serologically defined (SD) antigens and for the lymphocyte defined (LD) MLC determinants. One-way nonstimulation with the homozygous reference cells was taken as evidence for the presence of the respective MLC determinant on the tested cells. Four LD specificities (DL—50, 51, 52, 53) are defined by homozygous cells and at least three additional LD types can be recognised by their nonidentity with the known types. In this way 154 of 164 haplotypes in 82 beagles could be accounted for by seven MLC determinants. A strong association between the determinants of the LD and SD system was observed in the tested beagle population.