Conservation of recognition of antibody and T-cell-defined alloantigens between species of equids

Abstract

Serological and cellular assays and molecular techniques were used to define features of the major histocompatibility complex (MHC) of the donkey. With this information in hand, immune recognition of MHC determinants within and between donkeys and horses was compared. An antibody-mediated, complement-dependent, microcytotoxicity assay using a variety of antisera to donkey histocompatibility antigens, including those induced as a result of intraspecies or interspecies pregnancy in horse mares and jenny donkeys, delineated five donkey leukocyte antigen (DoLA) specificities. Antisera raised across species barriers (horse anti-donkey and donkey anti-horse) recognized polymorphic antigenic determinants in the target species. These determinants were often indistinguishable from polymorphic antigens recognized by alloantisera raised within horses or donkeys. The data indicate that a strong correlation exists between the serological antigenic types identified and the specificity of cytotoxic T lymphocytes raised by lymphocyte co-cultures, either within or between species. Moreover, in an analysis of a small number of donkey MHC class I cDNA gene sequences, no features distinguishing horse or donkey MHC class I molecules were identified. These molecular findings explain in large measure why antibody- and T-cell-defined alloantigen recognition is conserved among these closely related equids.