Subcellular Transplantation Antigen Derived from Dog Spleen Cells Cultivated in vitro . ∗

Summary

1. Millipore filtered tissue culture medium in which dog spleen cells have been cultivated in vitro was found to contain subcellular material with transplantation antigenic activity which could be concentrated by ultracentrifugation. Antigenic activity was demonstrated by the accelerated rejection by antigen recipients of a kidney homotransplant from the original spleen donor. 2. The antigenic material did not induce accelerated rejection of kidney homotransplants when injected back into the original spleen donor. 3. The Millipore filtered culture medium containing antigenic activity was apparently non-toxic when infused intravenously into homologous recipients.