Pretreatment with rh-GMCSF, but not rh-IL3, enhances PAF-induced eosinophil accumulation in guinea-pig airways.

Intraperitoneal injections of recombinant human granulocyte-macrophage colony stimulating factor (rh-GMCSF, 50 micrograms/kg-1 daily) or interleukin-3 (rh-IL3, 50 micrograms kg-1 daily) for two days, induced an increase in the percentage of bone marrow and pulmonary airway eosinophils in the guinea-pig. In addition, rh-IL3-treated animals exhibited an increase (21%) in blood neutrophils. Exposure of guinea-pigs to an aerosol of platelet activating factor (PAF) gives rise to a selective pulmonary eosinophil accumulation, maximal at 48 h. The eosinophilic response to PAF was significantly enhanced in rh-GMCSF-treated guinea-pigs but was suppressed in rh-IL3-treated animals.