Studies on relationship between serum properdin and cancer I. A modified method for the assay of serum properdin

1. Properdin assay which is comparatively sensitive and reproducible has been described. The assay may be called a modified method of properdin assay by HUNTER·HILL and McNALL. 2. The properdin assay of serum is possible by using a very small amount of test serum (0.1 ml at the least). The necessary amount of zymosan is very little, the procedure of properdin assay is comparatively simple and it can safely be used clinically. 3. Serum properdin of guinea pig, rat, rabbit and mouse can easily be measured by means of Rp and Ra made from guinea-pig sera. 4. In the properdin assay of human serum, human Rp serum IS preferable to guinea-pig Rp serum. 5. Human Rp serum is always prepared easily from pooled sera of advanced cancer bearing patients. 6. Insulin has not such ability of making Rp and R3 as can replace zymosan. 7. Properdin assay is possible by means of goat's hemolytic system as well as sheep's hemolytic system.