Effect of thymosin on lymphoid cells from human fetal organs.

Human fetal lymphoid cells from the thymus, blood, spleen, liver, and kidney of twelve 6-to-24-wk-old fetuses were studied for their ability to respond to thymosin by the alteration of E-rosette forming cells (E-RFC) and EAC-rosette forming cells (EAC-RFC). The preincubation of spleen cells with 100 micrograms thymosin-V1 effected a statistically significant increase in E-RFC, while no changes were observed in the lymphoid cells from blood or other organs. EAC-RFC assay revealed some increases in blood, thymus, and spleen; however, they were not statistically significant. Our results suggest that the fetal spleen may play an important role in the development of primitive immunocytes into mature cells and that this development is affected by thymic hormone.