Xenogeneic Reactivity of Human Fetal Lymphocytes

Summary In a local graft-vs-host reaction under a rat kidney capsule, spleen lymphocytes from 13-week-old human fetuses were capable of a xenogeneic immunologic reactivity. At 18 to 23 weeks of the intrauterine life, the reactivity was of the same magnitude as that of adult human lymphocytes. Fetal thymus cells were less active than fetal spleen cells. The results indicate that immunologic reactivity against xenogeneic cells is a genuine property of virgin unstimulated lymphocytes.