Susceptibility of equine chorionic girdle cells to lymphokine-activated killer cell activity

PROBLEM: Equine chorionic girdle cells are a subpopulation of highly invasive trophoblast cells that attach and invade the uterine epithelium on Day 35 (Day 0 = day of ovulation). These invading chorionic girdle cells form endometrial cups that are associated with a marked local maternal leukocytic response that may results in the demise of the cups at Day 120 of pregnancy. Once endometrial cups become established in the uterine wall they do not express MHC antigens, and therefore may only be susceptible to non-MHC restricted cytotoxic cells. The susceptibility of cultured chorionic girdle cells to LAK cell cytotoxicity was tested in order to evaluate the role of this type of cytotoxicity in the life-cycle of endometrial cup tissue. METHODS: Chorionic girdle cells from ten Day 34 conceptuses were collected, cultured, and used as a target cell in a lymphokine activated killer assay to determine if these cells were susceptible to lymphokine activated killing. RESULTS: Cultured chorionic girdle cells demonstrated similar in vitro morphological Features and patterns of antigen expression to those seen in vivo in endometrial cups. Cultured chorionic girdle cells were susceptible to lymphokine activated killing. CONCLUSIONS: Lymphokine activated killer cells may play a role in the degeneration of endometrial cup tissue. The potential mechanisms of regulation of uterine LAK cell activity in the horse are discussed.