Equine lymphocyte antigens in a Welsh pony family

Lymphocytes from an extended family of Welsh ponies were tested in a microcytotoxicity test against Thoroughbred and Arabian horse-derived antisera, which defined 4 and 6 equine lymphocyte antigen (ELA) specificities, respectively. Mixed leukocyte culture (MLC) tests were also performed. Welsh pony lymphocytes reacted to the Thoroughbred antisera. Most of the ponies' lymphocytes showed reactivity to 2 of the Thoroughbred ELA specificities, the offspring inheriting 1 antigen from each parent. Antigenic determinants were only partially demonstrated with Arabian antisera, although results indicated serologic identities among the ponies, which may reflect the historical background of the Welsh pony. There was no MLC reactivity between cells from most pairs of ponies that were ELA-identical, as typed with the Thoroughbred antisera, but cells from 2 ELA-identical pairs did react in MLC, indicating that MLC and ELA determinants may be on separate loci, as in other species.