Peripheral blood lymphocytes from healthy women were studied during pregnancy and postnatally, and were compared with lymphocytes from an age-matched non-pregnant control group. Compared with non-pregnant women, the total white cell count was significantly increased at all pregnancies and also post-partum. In pregnancy the absolute number and percentage of T lymphocytes was slightly elevated while almost no changes in B cells were found. No significant changes were found in the percentage of suppressor/cytotoxic (CD8+), of helper/inducer (CD4+) T lymphocytes, nor of CD4+/CD8+ ratio at any stage of pregnancy and puerperium. The most remarkable changes of the immune system occurred in the group of HLA-DR+ and CD56+ activated T cells. The cell numbers showed a significant increase in the first trimester (<14 weeks) and decreased slightly from stage to stage. Lower values in NK (natural killer) cells and higher levels of IL-2 receptor positive T lymphocytes did not reach significant levels of change.

Peripheral blood lymphocytes (PBL) from patients with ovarian or breast cancer or benign lesions of the breast, respectively, have been analysed for expression of phenotypic and activation markers by flow cytometry. The results were compared with those of a control group of healthy women. The relative proportion as well as the absolute counts of B lymphocytes were similar in both groups and in the control group. The absolute number of T cells was decreased in breast cancer patients (p < 0.05). The CD4+/CD8+ ratio was significantly depressed in ovarian cancer patients (p < 0.05), but not in breast cancer patients. In the ovarian cancer group, the percentage of CD3+ T cells expressing HLA-DR (p < 0.05) as well as CD3+ T cells expressing CD16 and CD56 (p < 0.05) was significantly higher. The relative proportion as well as the absolute counts of CD3+ T cells expressing the IL-2 receptor (CD25) were significantly higher (p < 0.001), respectively, in breast cancer patients (p < 0.05). These results suggest that gynaecological cancer is associated with specific alterations in the T cell population.