Distribution of T cell subsets in follicular fluid

Examination of follicular fluid (FF) from in vitro fertilization patients revealed a significant difference in concentrations of lymphocytes and T cell subpopulations with increased oocyte maturation. A total of 111 follicles containing 82 oocytes were aspirated from 10 patients undergoing laparoscopic oocyte retrieval. FF from 61.3% of the follicles was classified as clear and 38.7% as bloody, based on gross and microscopic appearance. A mean of 1.78 X 10(6) lymphocytes/ml was obtained from peripheral blood (PB) as compared to 2.14 X 10(5) and 2.79 X 10(5) lymphocytes/ml for clear and bloody FF, respectively. There were 6.3 X 10(5) T4 and 3.7 X 10(5) T8 lymphocytes in PB, resulting in a T4/T8 ratio of 1.72, which is not significantly different from that of the general population. The mean concentration of FF T4 and T8 lymphocytes decreased with increased oocyte maturation; the T8 reduction was statistically significant (P less than 0.05). The proportion of T4 to T8 lymphocytes in FF remained unchanged and was unaffected by maturity of the oocyte. Although estradiol (E2) did not vary with oocyte maturity, progesterone (P) increased and E2/P decreased. There was no correlation between E2 or P levels and distribution of T cells. Fertilization rates were higher in more mature oocytes, but there was no correlation between fertilization and E2, P, E2/P, or T cell subpopulations. It remains to be determined what factors result in the decrease in lymphocytes with increased oocyte maturity and the observed difference in FF T4/T8 compared to PB.