Nonspecific Immunological Mechanisms and Hormones

Pregnancy lymphocytes express progesterone receptors (PR). The regulation of lymphocyte PR expression is activation dependent, but hormone independent. There are at least two possible ways of recognition of fetally derived antigens by the maternal immune system. Shed antigens that appear in maternal circulation can be recognized by α/βT cells, or alternatively, antigens presented by the trophoblast might be recognized by γ/δT cells.