Understanding the response of dendritic cells to activation by streptococcal preparation OK-432.

ABSTRACT

BACKGROUND: The streptococcal preparation OK-432 induces maturation of T cells and dendritic cells (DCs). However, the mechanisms by which OK-432 induces DC maturation are not well understood. MATERIALS AND METHODS: The effects of OK-432 and TNF-alpha on peripheral blood mononuclear cells (PBMCs) were compared. Antibody-based approaches were used to detect proteins characteristic of antigen-presenting cells and cytokines. Cytotoxicity was evaluated by measuring the release of LDH after incubation of effector and target cells. The TLR-4 levels were measured by real-time quantitative PCR. RESULTS: Changes in cell surface marker levels were detected in both treatment groups but OK-432 had a greater effect on induction of Th-1-type cytokines. Furthermore, TLR-4 mRNA was up-regulated in cells from two out of five patients in response to OK-432, but not in response to TNF-alpha. CONCLUSION: OK-432 has a more profound effect on human DCs than TNF-alpha and may act through multiple signaling pathways.