The role of C-reactive protein and polyarginine in tumor immunotherapy

C-reactive protein (CRP) is an acute-phase reactant whose serum level rises rapidly in response to tissue injury. C-reactive protein binding to cells can activate the classical complement pathway, and enhance opsonophagocytosis. The polycation poly-L-arginine (PLA) can artificially fix CRP to target cells. The effects of CRP and PLA on tumor growth were evaluated, both independently and synergistically, using the V X 2 tumor line in the rabbit host. Ten normal animals and seven acute-phase animals were bilaterally inoculated with V X 2 cells (control side) and PLA-treated V X 2 cells (experimental side). Tumor growth was significantly retarded on the treatment side (P less than 0.005), in both animal groups. It is concluded that topical PLA is a potent inhibitor of V X 2 tumor growth. Comparison of normal and acute-phase animals revealed no persistent difference in tumor growth for either cell inoculum. Similarly, cell treatment with topical CRP did not inhibit tumor growth, whether PLA was present or not. Thus, circulating and topical CRP did not alter the rate of V X 2 tumor growth. PLA cytotoxicity remains to be evaluated when the agent is administered orthotopically, selectively, or systemically.