Enzyme cytochemical studies of the mononuclear phagocytic cells in human uterine fluid

Mononuclear phagocytic cells were present in normal uterine fluid. All transitional forms between monocytes and mature macrophages could be distinguished. The content of lysosomal enzymes in these cells was found to be identical to that of blood monocytes, which validates the hypothesis of their origin. Mononuclear phagocytic cells were more numerous in the uterine fluid aspirated from women with an intrauterine device (IUD). Furthermore, the activity levels of lysosomal enzymes in these cells were higher in the group of IUD users than in the nonusers, indicating a higher phagocytic activity of such cells in the IUD group, possibly secondary to the inflammatory process.The investigation purposes were to characterize the mononuclear phagocytic cells present in human uterine fluid according to their content of lysosomal enzymes and to compare the enzymatic activities of such cells in uterine fluid obtained from IUD users and nonusers. Uterine fluid was obtained from 15 healthy and normally menstruating women attending the clinic at the Malmo General Hospital in Malmo, Sweden. 10 of the women had use an IUD (TCu 200) for 6 months to 3 years; 5 used neither an IUD nor oral contraceptives (OCs). The fluid was aspirated using a sterile pediatric feeding tube. Only samples that were not contaminated with blood or cervical mucus were used. Aliquots of each sample were smeared on 5 separate glass slides. 1 smear was stained with May-Grunwald-Giemsa stain. The remaining smears were stained for the following lysosomal enzymes: alpha-naphthyl acetate esterase (ANAE); napthol AS-D chloroacetate esterase; acid phosphatase; and alkaline phosphatase. Blood smears were obtained from 5 healthy volunteers and stained identically for comparative purposes. Estimation of the content of each enzyme was based on the staining intensity in 20 randomly selected mononuclear phagocytic cells from each smear of uterine fluid or blood. Uterine fluid smears obtained from IUD nonusers contained only a few granulocytes and mononuclear phagocytic cells. These cells occurred in much higher numbers in the uterine fluid from IUD users. In May-Gunwald-Giemsa stained smears, some of the mononuclear phagocytic cells were morphologically similar to blood monocytes; they had round to oval nuclei, pale and finely granular chromatin, nearly invisible nucleoli, and a dusky blue cytoplasm that occasionally contained a few azurophilic granules. This finding was more common in the IUD group. The mononuclear phagocytic cells in uterine fluid obtained from both IUD users and nonusers showed strong ANAE activity, but the strongest activity was found in macrophages in the IUD group. Acid phosphatase activity was strong in many mononuclear phagocytic cells in uterine fluid from both IUD users and nonusers. The activity was strongest in mature macrophages in smears from IUD users. Granulocytes were strongly chloroacetate-esterase positive in uterine fluid as well as in blood smears. Positive stained material was often found in the cytoplasm of macrophages in uterine fluid, especially in the IUD group. Alkaline phosphatase activity was observed neither in blood monocytes nor in mononuclear phagocytic cells in uterine fluid.