Colocalization of the cysteinyl leukotriene type 1 receptor with eosinophils in asthma exacerbation. Double immunofluorescence staining for identification of colocalization of the cysteinyl leukotriene type1 (cysLT1) receptor with eosinophils in a bronchial biopsy from a patient with asthma with severe exacerbation. (a) cysLT1-receptor protein immunopositivity is illustrated with Texas red fluorescence. (b) Eosinophils stained with anti-human EG2 coupled to fluorescein isothiocyanate conjugate. (c) EG2+ eosinophils (internal scale bar = 10 μm). Nuclei are counterstained blue with 4',6-diamidino-2-phenylindole. EG2 is a monoclonal antibody to the cleaved (activated) form of eosinophil cationic protein. Reprinted with permission from Zhu and colleagues .