Basophils, eosinophils, and mast cells in atopic and nonatopic asthma and in late-phase allergic reactions in the lung and skin

Background: Previous studies used indirect methods to identify basophils in the bronchi in asthma, and the numbers were not compared with eosinophils and mast cells. Furthermore, differences in basophil numbers between atopic and nonatopic asthma at baseline and between late-phase skin and asthmatic reactions have not been previously documented. Objective: The basophil granule-specific mAb BB1 was used to identify basop hils in (1) bronchial biopsy specimens from atopic asthmatic subjects and n onatopic asthmatic subjects and control subjects, (2) biopsy specimens from atopic asthmatic subjects before and after inhalational allergen challenge , and (3) late-phase skin reactions. Basophil numbers were compared with EG 2(+) eosinophils and tryptase(+) mast cells. Methods: Cells were enumerated in bronchial and skin biopsy specimens by me ans of immunohistochemistry with the alkaline phosphatase-antialkaline phos phatase method. Results: There were elevated numbers of basophils in baseline biopsy specim ens in atopic asthmatic subjects compared with atopic control subjects or n ormal control subjects, although eosinophils and mast cells were 10-fold hi gher. There was an intermediate number of basophils in nonatopic asthmatic subjects. Basophils increased after allergen inhalation, but again basophil s were less than 10% of eosinophils. In contrast, basophils in cutaneous la te-phase reactions were approximately 40% of infiltrating eosinophils. The peak of basophil accumulation was at 24 hours, whereas maximal eosinophil i nfiltration occurred at 6 hours. One third of cutaneous basophils had morph ologic appearances suggestive of degranulation. Conclusion: Numerous basophils infiltrated cutaneous late-phase reactions i n atopic subjects. However, this cell was not prominent in bronchial biopsy specimens of asthmatic subjects, either at baseline or after allergen chal lenge.