IT has been shown that rabbit anti-serum against rat serum (RARS) injected intravenously into rats produces fatal anaphylactic shock¹. This was interpreted as a reaction of RARS with γ-globulins adsorbed on the cell surface². It therefore seemed reasonable to investigate the same effect on enhancing antibodies by injecting RARS into rats bearing Yoshida ascites sarcoma (YAS). The result was as expected–delayed death. It has been suggested that the “de-enhanced” tumour cells become more susceptible to lymphocytes³. Although the presence of enhancing antibodies coating YAS cells has not actually been shown, if they are responsible for the observed phenomena, other agents acting on γ-globulins should result in both anaphylaxis and “de-enhancement”. We therefore used cathepsins isolated from white blood cells, which act specifically on β and γ-globulins⁴. illustration

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