Use of resealed erythrocytes as delivery system for C-reactive protein (CRP) to generate macrophage-mediated tumoricidal activity.

We have shown previously in several mouse tumor systems that multilamellar vesicles (MLV) are an effective delivery system for generation of macrophage-mediated tumoricidal activity by C-reactive protein (CRP). Here we show that resealed erythrocyte ghosts (red cell ghosts, RCG) can function in the same manner. CRP associated with red cell ghosts (CRP-RCG) inhibited established lung metastases of T241 fibrosarcoma in C57B1/6J mice. The degree of inhibition was comparable to that observed with CRP-MLV. In other experiments, peritoneal exudate cells, obtained from mice pretreated with CRP-RCG i.p., inhibited growth and pulmonary metastases of T241 tumor in the Winn neutralization assay. Similar results were obtained with MCA-38 colon carcinoma in the Winn assay. These studies indicate that erythrocytes deserve consideration as another delivery system for biological response modifiers.