Treatment of guinea-pigs by a series of subcutaneous injections of histamine azoprotein, as an alum precipitate or with adjuvants, confers little or no protection against the effects of one MLD histamine injected intravenously. Guinea-pigs can be protected against passive anaphylaxis by a series of subcutaneous injections of histamine azoprotein. The protective effect is enhanced by adjuvants. Immunization with human serum and adjuvants appears to protect guinea-pigs against passive anaphylaxis

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... to approximately the same degree as treatment with histamine azoprotein and adjuvants, although adjuvants alone confer little or no protection against passive anaphylaxis. One or two subcutaneous injections of histamine azoprotein can sensitize a guinea-pig so that fatal anaphylaxis results after an intravenous injection of histamine azoprotein.