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

Abstract

Two antisera, B-442 and R-2046, were produced by immunizing offspring with purified peripheral blood lymphocytes from a parent matched for the ELA-A specificity carried on the unshared haplotype. Absorption analysis demonstrated that these antisera contained at least two families of cytotoxic antibodies, one directed against antigens present on T and B cells, and a second directed preferentially against antigens present on surface Ig positive cells. Immunoprecipitation studies using these antisera demonstrated that both antisera contain antibodies specific for glycoproteins with molecular weights characteristic of class I and class 11 MHC antigens. In lymphocyte typing tests of unfractionated lymphocytes, only the class I activity was readily detectable since the class I1 activity killed less than 25% of the cells.Family studies demonstrated that these antisera recognize products of genes linked to the ELA system. Based on two recombinants in an extended family it became apparent that the specificities detected by B-442 and R-2046 are not products of the ELA-A locus, but rather they are products of at least one other locus, defined in this paper as ELA-B. In this family a third recombinant was found between the A blood group system and the ELA-A locus. Based on these three recombinants, the most probable linear relationship of the following genes is: A blood group systedELA-MELA-B .

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

“…However the number of loci which are polymorphic has not been definitely determined. In the horse, Bernoco et al (1987b) have identified a second polymorphic class I locus using an antiserum which precipitated both class I and class I1 gene products.…”

“…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).…”

Joint Report of the Fifth International Workshop on Lymphocyte Alloantigens of the Horse, Baton Rouge, Louisiana, 31 October‐1 November 1987

“…The existence of additional loci encoding lymphocyte alloantigens has been reported based on recombination observed in family studies (Lazary ef al. 1986;Bernoco et al 1987b;Hirni et al 1988).…”

Serological and genetic study of the ELA W21 specificity

“…The first series, coded for by the locus A consists of more than 17 alleles (Bernoco et al 1987a). The existence of ELA specificities governed by a second locus (locus B) is also well documented, but only few alleles have been defined to date (Lazary et al 1986, Bernoco et al 1987b).…”