THE IMMUNOMODULATING GLYCOPROTEIN EXTRACT FROM KLEBSIELLA-PNEUMONIAE RU-41740 EXERTS A SUPPRESSIVE EFFECT ON HUMAN MONOCYTE DEATH BY APOPTOSIS

Programmed cell death or apoptosis is a physiological cell suicide pro cess that can be suppressed by survival factors. Monocytes undergo rap id apoptosis in culture, unless signalled by cytokines or the bacteria l lipopolysaccharide LPS. We have investigated the effect on monocyte apoptosis of the immunostimulating agent RU 41740 (Biostim), a glycopr otein extract from the Klebsiella pneumoniae K201 strain that is used for the prevention of recurrent infections. RU 41740, as LPS, strongly enhanced monocyte survival in vitro, an effect related to apoptosis s uppression. RU 41740 at concentration ranging from 1 ng/ml to 10 mu g/ ml prevented apoptosis induced both by survival factor deprival and by gamma-irradiation. Our observation suggests that enhancement of monoc yte survival may represent a component of the reported immunostimulati ng effect of this compound. (C) 1998 Elsevier Science B.V. All rights reserved.