FACTORS THAT STIMULATE THE PROLIFERATION AND SURVIVAL OF EOSINOPHILS IN EOSINOPHILIC PLEURAL EFFUSION - RELATIONSHIP TO GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR, INTERLEUKIN-5, AND INTERLEUKIN-3

To investigate the mechanism of eosinophilia in patients with eosinoph ilic pleural effusions, we measured the activities of eosinophil colon y-stimulating factor (Eo-CSF) and stimulating factor for eosinophil su rvival in the eosinophilic pleural fluids of six patients (two with tu berculous pleuritis, two with drug allergy, and one each with chronic eosinophilic pneumonia and pleuritis associated with rheumatoid arthri tis). The number of eosinophil colonies formed by the pleural fluid of patients with eosinophilic pleural effusions significantly exceeded t hat of control patients with noneosinophilic pleural effusions (7.5 +/ - 1.9 colonies/10(5) bone marrow cells, n = 6, versus 0.3 +/- 0.1 colo nies/10(5) bone marrow cells, n = 6, P < 0.01). Similarly, eosinophil survival evaluated on day 4 of culture with pleural fluid of patients with eosinophilic pleural effusions significantly exceeded that of pat ients with noneosinophilic pleural effusions (83.9 +/- 9.8 % versus 46 .1 +/- 11.2 %, P < 0.001). Both activities were inhibited mainly by an ti-IL-5 antibody and partially by anti-GM-CSF antibody and anti-IL-3 a ntibody. Mononuclear cells obtained from eosinophilic pleural fluid re leased the activities of Eo-CSF and stimulating factor for eosinophil survival in vitro. These findings suggest that GM-CSF, IL-5, and IL-3 are important to eosinophil accumulation in pleural cavity as stimulat ors of proliferation and survival of eosinophils.