CHARACTERISTIC CHANGES OF LARGE GRANULAR LYMPHOCYTES THAT STRONGLY EXPRESS CD56 IN ENDOMETRIUM DURING THE MENSTRUAL-CYCLE AND EARLY-PREGNANCY

Large granular lymphocytes that strongly express CD56 (CD56(++) LGL) c onstitute a major population of leukocytes in the secretory endometriu m and pregnancy decidua and are considered to be involved in reproduct ive immunity and in maintaining the pregnancy. The present study aimed to reveal the relationship between the characteristic changes of CD56 (++) LGL and altered hormonal environment and/or trophoblast invasion in the endometrium. Cell surface markers of CD56(++) LGL obtained from the endometrium during the menstrual cycle and early pregnancy were a nalysed using how cytometry, The percentages of both CD56(++) LGL that express activation antigens (CD69, HLA-DR) and those that express lym phocyte function associated antigen-1 (LFA-1) (CD11a/CD18) were highes t in the proliferative phase and decreased gradually throughout out th e menstrual cycle. Expression of these antigens was further suppressed in the late secretory phase, as well as in the early stage of pregnan cy. However, the percentage of CD56(++) LGL that express these antigen s was significantly higher in spontaneous abortions than in normal pre gnancies. On the other hand, the percentage of CD56(++) LGL that expre ss CD45RA was lower during normal pregnancy than during the menstrual cycle. The present results suggest that characteristics alterations of CD56(++) LGL are regulated by altered hormonal environment and by tro phoblast invasion.