A lipoteichoic acid fraction of Enterococcus hirae activates cultured human monocytic cells via a CD14-independent pathway to promote cytokine production, and the activity is inhibited by serum components

To elucidate the cellular activation mechanisms of lipoteichoic acid (LTA) compared with those of lipopolysaccharide (LPS), a quantitatively major LTA fraction, QM-IM, was prepared from hot phenol-water extracts of Enterococc us hirae (ATCC 9790) by hydrophobic octyl-Sepharose chromatography and by i on-exchange membrane (QMA-Mem Sep 1010) chromatography as a 60% 1-propanol- and 1 M NaCl-eluted fraction. Unlike the reference Escherichia coli LPS, Q M-1M did not demonstrate any ability to induce cytokines in a human whole b lood culture system in this study, whereas QM-1M induced a few cytokines su ch as interleukin (IL)-8 and tumor necrosis factor-alpha in human monocytic THP-1 cell and human peripheral mononuclear cell (PBMC) cultures in the ab sence of serum. Fetal calf and human sera decreased the above cytokine indu ction by QM-IM in THP-I and PBMC cultures, whereas sera increased activitie s of the reference LPS, IL-8 induction in the absence of serum in response to QM-1M was demonstrated to proceed through a CD14-independent pathway unl ike the reference LPS. (C) 1998 Federation of European Microbiological Soci eties. Published by Elsevier Science B.V. All rights reserved.