Quantitative studies in skin testing: V. The whealing reactions of histamine and ragweed pollen extract

1. 1. Variations in the site response to constant doses of intradermally injected histamine were observed. These differences closely paralleled those seen previously in the site response of ragweed-sensitive subjects to intradermally injected ragweed pollen extract. 2. 2. It is concluded that the antigen-antibody portion of the wheal mechanism is not implicated in the site differences, but rather it must be inherent in the differences of the skin itself. 3. 3. Within the range studied, the dose response of histamine approaches linearity on both logarithmic and semi-logarithmic plots. 4. 4. The variation seen in the histamine dose-response data is sufficient to account for the variation encountered in the ragweed dose-response data. 5. 5. Within the limits of the techniques employed, there is no evidence that there are other active substances besides histamine mediating the cutaneous whealing reaction induced by a specific antigen.