Bronchial mucosal structure after histamine inhalation.

Previous studies have shown an increased number of inflammatory cells and an increased level of hyaluronan in the bronchoalveolar lavage (BAL) fluid, 24 h after the inhalation of histamine. In the present report, the influence of histamine inhalation on the bronchial mucosa was, therefore, investigated in 20 subjects. Scanning electron microscopy (SEM) revealed that small areas of the mucosal surface were altered or lacked cilia more frequently in the bronchial biopsies taken 24 h after the inhalation of histamine than in the control biopsies. In contrast, light and transmission electron microscopy revealed no increase in epithelial damage and no changes in the subepithelial morphology. The results indicate that inhalation of histamine does not significantly alter the structure of the bronchial mucosa, which means that bronchial biopsies can be taken for routine morphological examination within 24 h after a histamine test. When using the biopsies in research, one should consider the possible influence of the histamine test.