RU-41-740 (BIOSTIM) AND IL-4, OR IL-13, HAVE OPPOSITE EFFECTS ON CD14, CD23, HLA-DR AND HLA-DQ ON MONOCYTES

RU41740 (Biostim) is a glycoprotein extract obtained from Klebsiella p neumoniae. Its immunostimulating properties on monocytes have been est ablished in vivo and in vitro. To confirm its spectrum of action at mo lecular level we studied its role on the modulation of four molecules involved in antigen presentation (HLA-DR, HLA-DQ), uptake of endotoxin (CD14) and activation (CD23). These four molecules are known to be mo dulated by interleukins IL-4 and IL-13. We found that HLA-DR, HLA-DQ, CD14 and CD23 were differentially regulated by Biostim and IL-4 or IL- 13. Surprisingly, Biostim inhibited the IL-4- or IL-13-induced express ion of CD23, HLA-DQ and HLA-DR, while it did not have any action on th ese molecules by itself. We therefore hypothesize that Biostim, throug h the action on its receptor, could interact with the IL-4 receptor an d IL-13 receptor and/or inhibit the IL-4- and IL-13 receptor transduci ng signal.