Bcl-x and Bax, but not Bcl-2, proteins are significantly expressed by eosinophils in eosinophilic tissues. (A) Immunohistochemical staining with the indicated antibody using nasal polyp tissues. Bcl-x and Bax, but not Bcl-2, proteins were detectable in tissue eosinophils. In the Bcl-2 panel, some representative eosinophils are marked with arrows. The Bcl-2⁺ control was bone marrow tissue from a patient with a B-cell lymphoma. Moreover, IL-5 protein was highly expressed in nasal polyp tissues. (B) Staining of tissue infiltrated by bladder cancer cells as well as eosinophils. Again, eosinophils expressed no detectable Bcl-2 protein (see cells marked with an arrow in the third panel), although high levels of the eosinophil hematopoietins were present in this tissue.