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

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.