Abstract
1) The serum properdin level was determined in a total of 133 cases of normal subjects, patients with malignant neoplasms, and other pathological conditions using the phage neutralization technique. i) The distribution and range of the PhN50 units in neoplastic patients are almost the same as in normal subjects. ii) There is on correlation between the slope values and the PhN50 units in cancer serum. iii) The neutralizing activity of a given serum against T3 phage is always higher than that against T2 phage without a constant ratio between the two. iv) In limited number of cancer patients, the PhN50 units and serum γ-globulin show a tendency to have negative correlation. v) No correlation can be established in cancer serum between the PhN50 units and the positive reaction to C-reactive protein antiserum, vi) The administration of a large dose of Mitomycin-C during a few days for the treatment of cancer results in a rapid fall in the PhN50 unit. A medium dose of the drug given once a week hardly shows such an ill effect.
2) The phage and modified zymosan assays were compared in a few cases of cancer along with the treatment. No parallelism can be found between the properdin units obtained by the phage and zymosan assay methods.
3) The relationship of properdin and the phage neutralizing capacity of a serum has been discussed in relation to the possible role of these factors in tumor immunity.
