Ovine endometrial cells fail to lyse K-562 target cells: a preliminary investigation

The ability of unfractionated and fractionated endometrial cells to lyse K-562 target cells was investigated within ewes during the late luteal phase of the estrous cycle (Days 12 to 14) and pregnancy (Days 16 and 19). In separate experiments, lymphokine activated killer (LAK) cells and endometrial cells, both designated as effector cells, were co-cultured with chromium-51 (51Cr)-labeled K-562 target cells in varying effector: target cell ratios. At 22 h, lytic activity was assessed by the release of 51Cr into the culture medium. The LAK cells exhibited lytic activity in a ratio-dependent manner, whereas the unfractionated and fractionated endometrial cells failed to lyse the target cells. For ratios combined, the rate of cytotoxicity for unfractionated endometrial cells recovered from ewes in the cyclic and pregnant (Days 16 and 19 combined) groups was 13.9 and 5.4%, respectively. Although the findings are preliminary, they indicate that ovine endometrial cells recovered during the late luteal phase and early pregnancy failed to exhibit natural killer activity upon K-562 target cells.