Lymphocyte alloantigens of the horse. I. Serologic and genetic studies.

This research aims to understand the genetic system that controls the lymphocyte alloantigens in horses, exploring its importance in immunological responses. The study employs a high number of sera screened for alloantibody using lymphocytes from various unrelated horses, establishing a connection between the Equine Leukocyte Antigen (ELA) and the maternal immunological response to fetal histocompatibility antigens in horses.

Details of the Research

The study delves deeper into the following areas:

• The research describes the genetic system controlling the lymphocyte alloantigens in horses, pointing to the significance of these alloantigens in the overall immune response of horses. Alloantigens are proteins present on the cells of a particular species that can provoke an immune response in a different member of the same species.
• The study utilized the alloantisera to paternal histocompatibility antigens that get prompted as a result of pregnancy in mares. This was used in the antibody-mediated and complement-dependent microcytotoxicity assays to identify 15 ELA specificities using cluster analysis. The microcytotoxicity assay is designed to test the toxicity of substances on microscopic organisms, and in this context, it was used to analyze the interaction between antibodies and equine lymphocytes.
• A total number of 369 sera were collected and screened for alloantibody using the lymphocytes from ten unrelated horses. Of these, 83% were found to have an antibody to lymphocyte alloantigens. After the initial cluster analysis, 120 of the most distinguishing sera were tested against further 400 horses.
• The study also successfully identified the phenotypic distribution of the ELA antigens in 304 arbitrarily selected horses, which showed that 13 of the alloantigens acted as members of a single allelic series, provisionally named locus ELA-A. These accounted for about 90% of the genes at this locus.
• It also noticed a remarkable difference in frequencies of the ELA-A specificities among the Standardbred and Thoroughbred breeds of horses. Rare ‘blank’ alleles suggested by the estimated cumulative gene frequency of known alleles at ELA-A were identified in informative families.
• The researchers posited that the ELA system might be the Major Histocompatibility Complex of the horse, although the evidence is not yet conclusive. The frequency of sensitization to ELA antigens in pregnant mares indicates the potential of the horse as a model for research on the maternal immunological response to fetal histocompatibility antigens.

This study provides useful information regarding the immune mechanisms in horses and might be instrumental in understanding interspecies immunological responses. Further research can explore the possibilities of the ELA system being the Major Histocompatibility complex in horses and delve deeper into inter-breed differences in ELA-A specificities.