INVOLVEMENT OF BETA(1) AND BETA(2) INTEGRIN STIMULATION IN RNA-SYNTHESIS IN AN EOSINOPHILIC CELL-LINE (EOL-1)

In allergic inflammatory disease, especially in bronchial asthma, eosi nophils play important roles as essential inflammatory cells. In the a ccumulation of eosinophils in airway inflammation, eosinophils receive very diverse stimuli. In this study, we investigated the influences o f the signal between beta(2) integrin/ intercellular adhesion molecule -1 (ICAM-1) or beta(1) integrin/fibronectin (FN) and RNA synthesis on proteins in eosinophilic cell line-1 (EoL-1), using recombinant solubl e ICAM-1 (r-sICAM-1) as a global response of eosinophils. H-3-thymidin e incorporation and H-3-uridine incorporation were used as indices for DNA synthesis and RNA synthesis, respectively. In a comparison of the RNA/DNA ratio with various durations of stimulation of 1 mu g/ml of r -sICAM-1 and 100 mu g/ml of FN, a time-dependent increase was observed , but the increase induced by FN rose slower than that induced by r-sI CAM-1. From this result, a beta(2) integrin/ICAM-1 signal induced an i ncrease in, the RNA/DNA ratio in EoL-1, implying that the signal promo tes RNA synthesis, which suggests that various types of protein synthe sis, such as the synthesis of various cytokines, are induced by the be ta(2) integrin/ICAM-1 signal. Similar results were obtained with a bet a(1) integrin signal using FN, but there was a difference in the time course between beta(2) integrin/ICAM-1 and beta(1) integrin/FN signals . This experimental method may be useful for understanding these manif estations as a global response of eosinophils.