Characterization of lymphocyte subpopulations and T cell activation in endometriosis.

PROBLEM: Numerous studies have characterized the lymphocyte subpopulations in normal eutopic endometrium and suggested a role for the cytokine secretory products of these lymphocytes in regulating endometrial cell proliferation and differentiation. Recent studies have shown that ectopic endometrium contains a greater concentration of scattered stromal lymphocytes than does eutopic endometrium. However, the lymphocyte subpopulations and their activation status have not been characterized in ectopic endometrium.

METHODS: We performed immunohistochemical studies on serial sections of proliferative and secretory phase eutopic endometrium and ectopic endometrium obtained during the proliferative phase using monoclonal antibodies to CD4 (T helper-inducer cells), CD8 (T cytolytic-suppressor cells), CD22 (B-cells), CD56 (natural killer cells), and VLA-1 (T-cell activation marker).

RESULTS: Ectopic endometrium contained significantly more scattered stromal CD4, CD8, and activated T cells than did proliferative and secretory eutopic endometrium. There were more activated T-cells in proliferative than in secretory eutopic endometrium. Ectopic endometrium contained significantly fewer NK cells than proliferative and secretory endometrium.

CONCLUSIONS: These results demonstrate that (1) the increased lymphocyte population in ectopic endometrium is due to increased numbers of CD4 and CD8 cells, and (2) a greater number of activated T cells are present in ectopic endometrium as compared to eutopic endometrium. Increased concentration of stromal T cells and enhanced VLA-1 expression in ectopic endometrium suggest that cytokine products of the activated T-cells may be involved in regulating cellular processes of endometriosis tissue.