The recruitment of leukocytes to an area of injury or inflammation site is one of the most fundamental host defenses. Pulmonary tuberculosis is characterized by granulomatous inflammation with an extensive infiltration of mononuclear cells. In tuberculous pleurisy pleural mesothelial cells are exposed to mycobacteria in the pleural space. In this study we demonstrate that mouse pleural mesothelial cells (PMCs), when stimulated with BCG or IFN- γ, produced MIP-1α and MCP-1 in vitro. IFN-γ enhanced the BCG-mediated MIP-1α and MCP-1 expression in a concentration-dependent manner. The RT-PCR studies also confirmed that both BCG and IFN-γ induce chemokine expression. IL-4 inhibited the BCG-mediated MIP-1α and MCP-1 expression in a concentration-dependent manner. The lower concentrations of IL-4 were ineffective; however, at higher concentrations, the inhibitory effect of IL- 4 persisted for 24 h and decreased thereafter. BCG stimulation resulted in an increase of IFN-γ and IL-4 receptors on PMCs. Our results demonstrate that Th1 and Th2 cytokines may regulate the C-C chemokine expression in PMCs and thus play a biologically important role in mononuclear cell recruitment to the pleural space.