Correlations of in vivo mediator release with late cutaneous allergic responses in humans. I. Kinetics of histamine release.

To evaluate the contribution of mast cell-derived mediators in the late cutaneous allergic response, the duration and quantity of antigen-induced histamine release was compared to the intensity of the antigen-induced skin reactions in atopic volunteers. Chambers containing either pollen extract or buffer were appended to denuded bases for 1 hr and were replaced hourly with buffer for 3 additional hr. These were compared to the extinction dilution skin test titer and to the mean diameters of the 20-minute wheal and induration at 6 and 8 hr after intradermal injection of antigen. Chamber-fluid histamine levels were significantly higher at antigen than at buffer sites throughout the 4 hr. The hourly histamine levels correlated with the size of the induration at 6 and 8 hr but not with the wheal size or skin test titer. We conclude that (1) histamine is released for at least 4 hr at skin sites of antigen challenge as a consequence of prolonged release either from individual or sequentially activated mast cells, and (2) the quantity of histamine released correlates with the intensity of the late-phase skin response. We hypothesize that histamine might be a marker for prolonged release from the mast cell of other mediators that are responsible for the late-phase response.