Variations in the percentages of lymphocyte subtypes during the menstrual cycle in women

In view of the well-known circadian variations in lymphocytes and their subtypes, we decided to study the possible variations in the proportions of these cells during the menstrual cycle in women. In order to do this, lymphocyte populations were determined during 3 successive cycles on D1, D13, D14, D15 and D25 in 6 women with 28-day cycles who were not on oral contraceptives. In each of these women, we then compared the percentages of lymphocyte subtypes during the different periods of the cycle; this amounted to over 400 comparisons. A statistically significant variation, at the 1% level was found in only one case, when comparing the percentages of T4 lymphocytes on D1 and D13. In the light of this experience, we can therefore assume that there are no statistically significant variations in the proportions of lymphocyte subtypes during the menstrual cycle in women, which does not exclude the possibility of variations in their total numbers.