Detection of IL-9R immunoreactivity on peripheral blood and BAL eosinophils.

(A) Specific staining was detected on the cell membrane (solid arrow) as well as the cytoplasm (open arrow) of purified peripheral blood human eosinophils. (C) Positive staining of BAL eosinophil (solid arrow) from asthmatic individual. Normal rabbit serum was used as the negative controls for the (B) peripheral blood eosinophils and (D) BAL cells. (E) Quantification of IL-9R–α⁺ cells in asthmatics and nonasthmatic controls. The percentage of IL-9R–α⁺ peripheral blood eosinophils from asthmatics and nonasthmatic controls was determined by counting 500 cells per slide. There was no significant difference between the 2 groups using immunocytochemical methods to detect the IL-9R–α (P > .05). The staining was performed using the affinity-purified rabbit pAb anti–IL-9R–α (directed to C-terminus specific domain; final dilution, 1 μg/mL) followed by biotin-labeled swine antirabbit Ig and streptavidin phosphatase alkaline. Counterstaining was performed using hematoxylin.