Maternofetal Passage of Leukocytes and Platelets in Man

Human maternal whole blood was treated with Atabrine in vitro, and the cellular portion returned to the maternal circulation within 15 hours of the time of delivery in nine cases. In three cases no fluorescent forms were found in the cord blood. In six cases fluorescent forms were observed in the cord blood, in four instances platelets, in four granulocytes, and in three lymphocytes. Three normal controls received the supernatant, Atabrine-containing plasma from 350 ml. of their own whole blood to which had been added 50 or 100 mg. of Atabrine. No fluorescent forms were found in the buffy coats of these individuals over a 24-hour period.

The data are interpreted as suggesting human transplacental passage, from mother to fetus, of small numbers of leukocytes and platelets. Particular interest is thought to attach to the identification of labeled lymphocytes in the cord blood because of the evidence that some mononuclear leukocytes which normally circulate are still capable of multiplication and pluripotentiality.

The possibility of human lymphocytic chimerism on the basis of maternofetal transplacental passage is suggested, although no evidence for permanent colonization and immunologic function is presented. The relation of this concept to those human diseases in which autoimmunity is thought to play a major role is discussed.