Normal immunosuppressive protein inhibition of human and murine lymphoblastoid cell line proliferation

Normal immunosuppressive protein, prepared from human plasma by DEAE-cellulose chromatography, inhibits DNA synthesis in human cell lines of lymphocytes of both T and B origin. It also inhibits [3H]thymidine incorporation in mouse cell lines. Normal immunosuppressive protein was able to inhibit the proliferation of these cells, although they were already transformed and had a high rate of DNA synthesis. On the other hand, it does not inhibit myeloid cells or fibroblasts.