Polygenic Control of Mixed Lymphocyte Reactions in Dogs

Abstract

The genetics of the MLR of the dog are studied using LD typing cells. The four new homozygous reference cells described bring the total number of defined LD specificities in this species to 11. In families, LD specificities generally segregate en bloc with the SD specificities of the DLA complex. The recombination frequency between the SD and LD loci is provisionally estimated to be 0.007. A slight but significant stimulation between two SD identical LD typed siblings could not be explained on the basis of a single recombination between the SD loci and one LD locus and therefore suggested the existence of an additional LD system. Unrelated SD different individuals with two different LD determinants in common frequently stimulate each other in MLR, but low responses are also encountered. The results described are compatible with a hypothesis of two segregant series of alleles for the genetic control of the MLR and linkage disequilibrium between certain alleles of these series. More conclusive evidence of the validity of this hypothesis and further knowledge of other factors which determine the response in the MLR are required before a reliable estimate of the importance of LD structures in histocompatibility can be made.

Secondary Responses of Alloantigen‐Primed Dog Lymphocytes

“…The positive reactions found on secondary culture of cells stimulated with lymphocytes that do not share the sensitizing DLA-LD determinants with the primary stimulator indicate that genetic factors different from LD must be involved. A considerable number of observations argue against the genetic control of mixed lymphocyte reactions in dogs by only one locus (Bijnen et al 1977(Bijnen et al , 1979. The one LD locus model used in this paper is therefore probably an oversimplification.…”

“…Gene products of an additional LD locus (or loci) could be t h e cause of the positive reactions against cells not sharing any known LD allele with the primary stimulator. Such a locus (or loci) may be located within (Grosse-Wilde et al 1975, Bijnen et al 1977, Fuller et al 1978 or without the MHC (Nunez-Rodan e t al. 1978, Singd 1978.…”

“…A panel of 70-90 different alloantisera was used in a onestage microcytotoxicity test to type for the currently known serologically defined antigens of the DLA complex as previously described (Vriesendorp 1973). LD typing was performed using a panel of homozygous "typing" cells as stimulator cells in MLR's (Grosse-Wilde et al 1973, Bijnen et al 1977.…”

“…LD antigens are commonly identified by using lymphocytes of DLA-LD-homozygous dogs as stimulator cells in Mixed Lymphocyte Reactions (MLR's) (Grosse-Wilde er al. 1973, Bijnen et al 1977. The relatively long culture period (5-7 days) and the difficulties in and costs of finding or breeding suitable LD-homozygous dogs limit the usefulness of MLR's for immunogenetic studies.…”