Analysis of the survival of mature human eosinophils interleukin-5 prevents apoptosis in mature human eosinophils

Abstract:  Analysis of the survival of mature human eosinophils: interleukin-5 prevents apoptosis in mature human eosinophils. Yamagu chi Y, Suda T, Ohta S, Tominaga K, Miura Y, Kasahara T. Department of Medical Biology and Parasitology, Jichi Medical School, Tochigi-ken, Japan. We and other groups have previously shown that interleukin-5 (IL-5) maintained the viability of mature eosinophils in an in vitro liquid culture system. Mature eosinophils did not proliferate but their survival was maintained in the presence of IL-5. Using this culture system, we investigated the mechanism of IL-5-mediated survival. In the absence of human IL-5 (hIL-5) mature eosinophils succumbed after 4 days, while in the presence of hIL-5 they survived up to 10 days. When DNA extracts of cultured eosinophils were analyzed on an agar gel electrophoresis, marked DNA fragmentation was observed in the absence of hIL-5, while no significant DNA fragmentation was observed in the culture with hIL-5 for 48 hours. The DNA fragmentation appeared as early as 6 to 12 hours after hIL-5 deprivation. Concomitantly, IL-5 stimulated total RNA and protein synthesis, but did not induce DNA synthesis in mature eosinophils. Because cycloheximide or actinomycin D impeded the protection of apoptosis by hIL-5, some new RNA and protein synthesis appeared to be required in this phenomena. These findings indicate that IL-5 maintains survival of mature eosinophils with induction of new RNA and protein synthesis, thus leading to the inhibition of apoptosis. PMID: 1726704 [PubMed - indexed for MEDLINE]