On the Failure of Azo-gelatin

The non-antigenicity of gelatin was attributed for a long time to its lack of aromatic amino-acids. Later, Landsteiner [1919] and Hooker & Boyd [1932] introduced aromatic determinant groups into the gelatin molecule by coupling it with diazotized arsanilic acid. Injection of arsanil-azo-gelatin into rabbits furnished inmmune sera which gave slight precipitates with the arsanil-azo-compounds of casein, ovalbumin and serum-globulin, but gave no visible reaction with arsanil-azo-gelatin. Similar results were obtained by coupling gelatin with glucosido-tyrosine [Clutton, Harington & Yuill, 1938]. These experiments demonstrated clearly that the absence of antigenicity in gelatin cannot be attributed merely to the deficiency of aromatic groups. In previ9us papers [Haurowitz, 1936; Haurowitz & Kraus, 1936] we showed that the bulk of intravenotsly injected arsanil-azo-globulin is fixed in the liver and the bone-marrow of rabbits. We have now performed similar experiments with arsanil-azogelatin. METHODS