PROBLEM: Human endometrium contains up to 40% leukocytes. Since their function is unclear, we cultured these cells separately to analyze their proteolytic potential in vitro.
METHOD: Endometrium was obtained from hysterectomies or from first trimester abortion. After collagenase digestion, the different leukocyte subsets (CD56, CD3, CD19, CD16, CD45) were immuno-separated and cultured. Gelatine zymography and a quantitative type IV gelatinase assay were run on all culture supernatants.
RESULTS: On zymography, all subtypes of endometrial leukocytes released gelatinases. The 72-kDa gelatinase was absent from peripheral leukocyte supernatants, whereas it was secreted by all endometrial leukocytes. The 92-kDa gelatinase was present in all culture supernatants. Large granular lymphocytes (CD56+, LGL) expressed the highest type VI gelatinase activity as compared to all other leukocytes. This activity increased during the cycle in LGL and T cells but remained unchanged in glandular and stromal cells.
CONCLUSIONS: Endometrial leukocytes, particularly LGL, secrete significant amounts of gelatinases.