PERFORIN EXPRESSION IN HUMAN CELL-MEDIATED LUTEOLYSIS

After ovulation and in the absence of fertilization, the human corpus luteum regresses in an orderly sequence of morphological changes. This study demonstrated that luteal regression involved progressive infilt ration of lymphocytes and macrophages. The inflammatory infiltrate beg an in the theca externa and gradually invaded granulosa cells, with ma ximum accumulation of lymphocytes and macrophages at the time of menst ruation. Immunoperoxidase staining showed that the majority of lymphoc ytes were CD2(+), CD3(+), CD8(+) T lymphocytes, and 15% of these T cel ls expressed perforin, a cytolytic protein implicated as a mediator of cytotoxicity. The remaining mononuclear infiltrate showed strong reac tivity with monocyte/macrophage markers. These findings indicate that (a) a physiologic cell-mediated inflammatory process in the regressing human corpus luteum is mediated mainly by CD8(+) T lymphocytes and ce lls of monocyte/macrophage lineage and (b) perforin expression in T ly mphocytes supports a possible role for cytolytic T cells during the ph ysiologic inflammatory response in human luteolysis.