Joint Report of the Fourth International Workshop on Lymphocyte Alloantigens of the Horse, Lexington, Kentucky, 12–22 October 1985

Abstract

Summary. The workshop consisted of 12 monthly cell exchanges of full‐sibling families among the 10 participating laboratories. A total of 33 parents, 52 offspring and five unrelated horses were typed by each laboratory using local antisera. The raw data were submitted for central analysis before any identification of the animals was revealed. Confidence derived from the consistent agreement between the laboratories on the assignment and segregation of the first 10 ELA‐W specificities led to the removal of the W (workshop) notation and acceptance of full status as locus A antigens. The seemingly supertypic W11 specificity, however, remained unchanged. Ten additional specificities were seen to segregate with the ELA system, suggesting either splits of previously described specificities or products of linked loci. The workshop (W) notation was given to the 10 specificities W12‐W21, befitting their status as specificities under study. The previously described ELY‐1.1 specificity, characterized by segregation independent from the ELA system, was confirmed along with a new specificity, ELY‐1.2, which behaves as an allele of ELY‐1.1. For informative families, the two specificities showed codominant expression and appeared to constitute a closed, autosomal system. The ELY‐2.1 specificity was confirmed to segregate independently from the ELA‐A and ELY‐1 loci.

At least two loci encode polymorphic class I MHC antigens in the horse

“…ELA typing. Horses were typed for ELA and other lymphocyte alloantigens using reagents and methods standardized in International Workshops (Bernoco et al 1987a).…”

“…A number of genes have been mapped to the ELA region (equine lymphocyte antigen, the major histocompatibility complex of the horse), including those encoding class I and class I1 MHC antigens (Lazary et al 1980;Bernoco et al 1987a), the A blood group antigen (Bailey et al 1979), a Q-10 like molecule (Lew et al 1986b) and a Tlt like trait (Bailey 1986). However, the biochemical characterization of equine MHC antigens and the identification of multiple loci in the class I and class I1 regions has been minimal (Bernoco et al 1987b;Lazary et al 1986).…”

Evidence of a second polymorphic ELA class I (ELA‐B) locus and gene order for three loci of the equine major histocompatibility complex

“…One class I locus has been clearly identified thus far with 11 internationally accepted specificities which are products of allelic genes of the ELA-A locus. An additional 10 specificities were described during the Fourth International Workshop as segregating with the ELA system, but their genetic relationship with the ELA-A locus specificities was not fully elucidated (Bernoco et al 1987). It is possible that some of these additional specificities are products of different ELA loci closely linked to the ELA-A locus.…”

“…It is possible that some of these additional specificities are products of different ELA loci closely linked to the ELA-A locus. Indeed, one of these specificities, BER-B 1 (later accepted as international specificity ELA-W13 [Bernoco et al 1987]), was separated from the ELA-A locus by a recombination event which produced different mixed lymphocyte culture reactivity within a family compared to that predicted by ELA typing, i.e. an apparent recombinant between the class I and class I1 loci of the horse ).…”

Localization of the equine major histocompatibility complex (ELA) to chromosome 20 by in situ hybridization

“…The MHC of the horse is designated the equine lymphocyte antigen (ELA) system (BAILEY et al 1979;LAZARY et al 1980). This system has been studied extensively with serological methods, and two closely linked class I loci, designated ELA-A and ELA-B, have been defined (BERNOCO et al 1987a(BERNOCO et al , 1987b. Southern blot analysis using human MHC class I and class I1 probes have been used to study the organization and polymorphism of equine MHC genes (ALEXANDER et al 1987;GUERlN et al 1987).…”