Histocompatibility testing in dogs. II. Leukocyte typing in relation to the mixed lymphocyte culture (MLC) reactivity

The correlation between MLC reactivity (LD) and serological leukocyte typing (SD) was studied in a beagle colony. Disparity for a serologically defined non-DL-A lymphocyte antigen did not correlate with MLC reactivity. Lymphocytes of colony members with common ancestors and SD identical DL-A haplotypes did not stimulate each other in the MLC. This implies that LD typing in the beagle coolony can be generally predicted by DL-A SD typing. Consequently, lymphocytes of sibs homozygous for a given DL-A SD haplotype could be shown, with few exceptions, to be also homozygous for MLC determinants. Cells of these homozygous sibs can be used in MLC typing as reference cells for DL-A LD specificities. Two exceptions to the expected linkage between DL-A SD typing and MLC reactivity were found. These findings could not be explained by recombination with the DL-A region assuming a single major LD locus coding for MLC. Thus, suggestive evidence for more than one single LD locus has been obtained.