The incidence of pleural infection has been rising in recent years. Intrapleural therapy with tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) has significantly reduced the need for surgery, and its impact on clinical care is rising worldwide. Efforts are underway to optimize the delivery regimen and establish the short and longer term effects of this therapy. The complex interactions of bacterial infection within the pleura with inflammatory responses and clinical interventions (antibiotics and tPA/DNase or other fibrinolysins) require further studies to improve future treatment options. Intrapleural instillation of tPA potently induces pleural fluid formation, principally via a monocyte chemotactic protein (MCP)-1 dependent mechanism. Activation of transcriptional programs in pleural resident cells and infiltrating cells during pleural infection and malignancy results in the local secretion of a cocktail of proinflammatory signaling molecules (including MCP-1) within the pleural confines that contributes to effusion formation. Understanding the biology of these molecules and their interaction may provide novel targets for pleural fluid control.