Studies on relationship between serum properdin and cancer III. Influence of anticancer agents on the serum properdin level

1. When the various anticancer agents are injected intravenously to normal rabbits and intraperitoneally to normal mice, it seems that the serum properdin levels fall transitorily for some hours after administration with a small dose and then keep rising, but with a massive dose it continues to fall from the beginning. 2. The properdin level is decreased considerably by Thio-TEPA and Carzinophilin; moderately by Mitomycin C; and slightly by M. H. OX-substance hardly changes the level and 8-azaguanine rather has a tendency to raise the level. 3. The administration of most anticancer agents seems to suppress the properdin system. 4. The influence of these agents on human serum properdin is similar to that of rabbits. 5. The properdin levels keep at high titers in the group to which the agents act effectively on the cancer, but the levels fall down more rapidly and animals die earlier in the group to which the agents act ineffectively on the cancer as compared with the control group.