Effect of cytokines and fibroblasts on eosinophil viability in patients with nasal polyps.

Background: Eosinophilic infiltration is the most prominent histologic feat ure of nasal polyps. The effects of eosinophil-associated cytokines and fib roblast derived factors on survival of isolated eosinophils from blood of p atients with nasal polyps were investigated. Methods and Patients: Peripher al blood eosinophils of 9 patients with nasal polyps were incubated in 1. c ulture medium alone and in a medium containing, 2. IL-5 (10 pg/ml); 3. IL-3 , IL-5, GM-CSF(10 pg/ml); 4. supernatants of fibroblasts cultured from poly ps of the same 9 patients; and 5. supernatants of fibroblasts enriched with IL-5, 3, and GM-CSF. Viability of eosinophils was assessed by their abilit y to take up WST-1. Results: The survival index (T-50) Of eosinophils cultu red in different culture medium is listed as follows: 1. medium alone: 0.8/-0.14 days (MV +/- SEM), 2. medium containing IL-5: 1.2 +/- 0.19 days, 3. medium containing IL-3, IL-5, and GM-CSF: 3.1 +/- 0.13 days, 4. fibroblast supernatants: 1.6 +/- 0.29 days, and in 5. fibroblast supernatants enriched with IL-3, IL-5 and GM-CSF: 2.2 +/- 0.21 days. Conclusion: IL-5, prolongs eosinophil survival in vitro. IL-3, IL-5 and CM-CSF revealed synergistic ef fects; survival of eosinophils was significantly prolonged in comparison to stimulation with IL-5 alone. Supernatants of fibroblasts also prolonged eo sinophil survival. This effect is probably due to GM-CSF, which was found i n high concentrations in fibroblast supernatants.