Serum Complement in the Rejection of Sarcoma I Ascites Tumor Grafts

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Abstract
Summary: The reactivity of sarcoma I, isoantibody, and complement (C′) was studied in vitro and in vivo. C′ activity was needed in the cytotoxic reaction in vitro. When inoculated into the peritoneal cavity of presensitized mice, tumor cells bound mouse γ-globulin and C′ (β1C protein) within 2 min. Tumor growth resulted in decreasing serum C′ titers. There was a positive relation between the number of tumor cells implanted, loss of C′ activity and death of the recipient animals. B10D2/new line mice which possess a lytic C′ system were at least 10 times more efficient in the destruction of tumor implants than B10D2/old line mice which lack C′5 activity. It is concluded that C′ participates in the rejection reaction against allografted sarcoma I tumor and that biologic functions dependent on the activity of C′5 are preeminent in the graft destruction. A second mechanism was independent of C′5 and less efficient.