T-lymphocyte reactivity during the menstrual cycle in women.

Reactivity of blood lymphocytes to nonspecific mitogenic stimulation with phytohemagglutinin (PHA) was measured in nine healthy, regularly cycling women at three phases of their menstrual cycles corresponding to peak levels of estradiol (midfollicular phase), peak levels of progesterone (midluteal phase), and the lowest levels of both hormones (menstrual phase). Sampling points were verified by radioimmunoassay of estrogen, progesterone, luteinizing hormone, and follicle-stimulating hormone. There were significant increases in reactivity associated with an increasing concentration of PHA and with autologous plasma vs AB plasma. However, no differences were found in reactivity to PHA over the three menstrual cycle phases and correlational analyses indicated no relationship between counts and any of the hormones measured.