Research Article

Essential Roles of PKA, iNOS, CD95/CD95L, and Terminal Caspases in Suppression of Eosinopoiesis by PGE2 and Other cAMP-Elevating Agents

Figure 2

PGE2 upregulates and dexamethasone prevents iNOS expression in developing eosinophils. Bone-marrow cultures were established in the presence of IL-5, alone or associated with PGE2 (10−7 M), dexamethasone (10−7 M), or both. All cultures were maintained for 2 days, before collecting cells for detection of iNOS by immunocytochemistry. Because (bright red) cytoplasmic staining for iNOS (insert) suffers interference from (brown) cytoplasmic staining for EPO, eosinophils were identified in this experiment by their donut-shaped nucleus [6] and homotypical aggregation pattern [9], after counterstaining with Harris’ hematoxylin. Arrowheads in the upper right panel point to iNOS-negative cells showing nuclear changes (chromatin condensation/nuclear fragmentation) suggestive of apoptosis (compare with upper left and lower left panels). Insert shows details of cytoplasmic staining of cells exposed to IL-5 plus PGE2. Magnification 400x (under oil).
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