Inhibition of Tumor Growth by Recognition Factors

Summary

Recognition factors have been demonstrated to constitute one component of macrophage surveillance. Since depletion of plasma recognition factors occurs in experimental and clinical neoplasia, studies were undertaken to evaluate the contribution of macrophages and recognition factors to neoplasia. Employing Shay chloroleukemic cells as the transplant, the administration of recognition factors at the tumor cell transplantation site induced an 86% decrease in tumor weight. Specificity of this inhibitory response on tumor growth was demonstrated by the observation that administration of human serum albumin resulted in no modification in tumor growth. The isolated recognition factor fraction enhanced phagocytosis in vitro and also exerted a pronounced chemotactic effect. Macrophages and recognition factors may be of significant importance in tumor cell detection and rejection mechanisms.

This investigation was supported, in part, by NIH Research Grant CA 13746 from the National Cancer Institute.

The authors would like to acknowledge Dr. Eugene Handler of Hunter College for initially providing the Shay chloroleukemia tumor-bearing Long–Evans rats.