In this work we characterize the Mycobacterium bovis bacillus Calmette‐Guérin(BCC) ‐induced pleurisy and investigate the role of chemical mediators and cytokines in BCG‐induced granulocyte accumulation at 24 h. Intrathoracic injection of BCG in C57B1/6 mice induces a biphasic inflammatory reaction with intense leukocyte accumulation at 24 h and 15 days. Neutrophils were observed in the pleural cavity at 4‐24 h, mononuclear cells and eosinophils after 24 h. A new wave of mononuclear cells and neutrophils were observed after 15 days. Pretreatments with dexamethasone, BW 755C, BW A4C, WEB 2170, L‐NAME, and monoclonal antibody (mAb) anti‐interleukin‐5 (IL‐5; TRFK‐5) had inhibited the eosinophil accumulation. On the other hand, only the pretreatments with dexamethasone, L‐NAME, or mAb antitumor necrosis factor a (TNF‐α; MP6‐XT3) had inhibited the neutrophil influx. These results suggest the involvement of leukotrienes, platelet‐activating factor, nitric oxide, and IL‐5 in the eosinophil accumulation, and a role for nitric oxide and TNF‐α in the neutrophil influx induced by BCG. J. Leukoc. Biol. 62: 778–785; 1997.

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