Purpose of review: Lymphocytic pleural effusions are characterised by divergent cellular responses depending on the etiology of disease. The pathogenic role of lymphocytes in pleural disease, however, remains unclear. This review provides a basic description of the functions of the different lymphocyte subsets within the pleural space and then summarises recent studies of lymphocyte biology in pleural disease.
Recent findings: The mechanisms of lymphocyte trafficking into the pleural space have been clarified. Specific adhesion molecules (such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and chemokines (CXCL13, interleukin-8, and monocyte chemotactic protein-1) have been identified as important factors involved in the accumulation of lymphocytes during inflammatory pleuritis. Both cellular and soluble factors may contribute to impaired T-cell immunity in malignant pleural effusions. Studies of natural killer cell and gammadelta T-cell biology indicate that these lymphocyte subsets may also play a role in the pathogenesis of pleural disease. The dominant Th1 response characterised by tuberculous pleuritis may allow for rapid diagnosis of disease. Furthermore, strategies for improving cytotoxic T-cell and natural killer cell function show promise for treatment of malignant pleural disease.
Summary: Recent work has provided insight into the pathogenesis of disease in lymphocytic pleural effusions. Further study of specific cellular responses may offer significant opportunities in the diagnosis and management of these disorders.