Long-Term Survival of Mouse Thymic Lymphoid Cells in Vitro: Effect of Human Serum

Abstract

Long-term survival of mouse thymus cells in vitro was obtained with a medium containing human serum. Almost 90% of floating thymic lymphoid cells continued to live for at least 2 weeks, far longer than the normal life span in vivo. On the contrary, only 0.1% of the cells survived in the medium with fetal calf serum after 2 weeks cultivation. Cultivated thymocytes were markedly stable; the number of viable cells was constant and no proliferation was noted throughout the culture period except during the 1st day. Half of the CBA thymocytes maintained θ isoantigen during the 2-week culture period. They showed very weak responsiveness toward alloantigens which is common in fresh thymocytes. Proliferation was enhanced by either syngeneic or allogeneic stimulation only in neonatal thymocytes after 1-day cultivation but was not observed in fetal or adult thymocytes. The present report also offers evidence that thymocytes specifically stimulate proliferation of allogeneic bone marrow cells.