It has been shown that antianaphylaxis is not caused by a partial saturation of cellular or humoral antibodies by the following facts.
1. Guinea pigs passively sensitized with anti-horse or antipneumococcus serum and specifically desensitized do not manifest as great a reactivity upon resensitization with the same antiserum as upon the original sensitization.
2. Guinea pigs passively sensitized with anti-Friedländer Type B serum or antipneumococcus Type II serum and specifically desensitized do not attain the same degree of reactivity as normal animals when passively sensitized with anti-horse serum.
3. Guinea pigs passively sensitized with anti-Friedländer Type B serum and desensitized with the specific carbohydrate remain as resistant to infection with Friedlander's bacillus Type B as undesensitized guinea pigs. Since in this case, at least, it is agreed that type-specific immunity and type-specific hypersensitiveness are due to the same type-specific antibody, a change in anaphylactic response should be accompanied by a change in immune response, provided this change depends on antibody balance.
4. A determination of the antibody content of the serum of sensitized as well as of desensitized guinea pigs by mouse protection tests indicates that a loss of reactivity in desensitized animals cannot be adequately accounted for on the basis of depletion of circulating antibody.
These experiments suggest that hypersensitiveness and resistance are different manifestations of the same antigen-antibody reaction while antianaphylaxis is a state of refractoriness which is due neither to excess of circulating antibody nor to antibody depletion, but is the result of secondary changes the true nature of which is still not definitely established.