[The influence of pregnancy specific serum factors on the mitogen induced culture of lymphocytes (author's transl)].

The addition of 10% serum of pregnant patients to a culture of lymphocytes from healthy non-pregnant control persons inhibits the stimulation of these lymphocytes by the mitogens phytohemagglutinin (PHA), pokeweed mitogen (PWM) and concanvalin A (Con A). The inhibitory effect increases with increasing duration of pregnancy. Sera from pregnant patients which already inhibit during the first trimester of pregnancy show an increase of this effect with increasing length of gestation. The influence of several hormones and proteins was investigated in order to detect a factor in the pregnant serum responsible for the inhibition of the lymphocyte culture. Compounds which are known to increase during gestation were added as pure compounds in various concentrations to the lymphocyte culture. An inhibitory effect on the lymphocyte culture in vitro was shown dependent on the amount, by human placental lactogen, alpha-fetoprotein, human chorionic gonadotropin, cortisol, progesterone and SPI glycoprotein and alpha-2-macroglobulin. The estrogens estriol and estradiol in physiologic dosages did not show an inhibitory effect and showed a stimulatory effect in higher dosages.