Inflammatory cells and mediator release during ragweed challenge: correlation between histamine content in nasal secretions and appearance of inflammatory cells.

The early and late phase responses in the nasal tissues exhibit release of inflammatory mediators and a mixed cellular influx in separate nasal challenges. To explore this phenomenon further, histamine concentration was determined along with characterization of cell influx during dose-dependent ragweed challenges. Ten subjects with allergic rhinitis underwent two unilateral nasal lavages using incremental 3-fold concentrations of short ragweed. Low doses of ragweed (0.016 to 0.114 units Amb a I) rarely induced cell influx (1/18 challenges), whereas moderate doses (0.432 to 1.3 units Amb a I) caused cell influxes in 7/18 and high doses (3.39 to 11.7 units Amb a I) resulted in cell influxes in 8/17. The eluent contained greater than 50% neutrophils in seven challenges; greater than 50% eosinophils in three; and a mixed pattern in six. There was a significant association between the dose of antigen and the level of histamine. Challenges with an eosinophilic influx tended to be associated with higher concentrations of histamine than neutrophilic influxes. Similar to the immediate skin response, the early allergic response in the nose demonstrated a cell influx with release of histamine. Nasal cellular inflammation therefore can occur within minutes of allergen exposure.