Aim: To investigate the regulatory effects and the related mechanisms of streptococcal protein on the immunologic activity of RAW264.7 murine macrophages.
Methods: RAW264.7 cells were incubated with different concentrated streptococcal protein respectively. The proliferation of RAW264.7 cells was determined by MTT assay. The phagocytosis of macrophages was analyzed by neutral red phagocytosis assay. The activities of IL-6 and TNF-alpha in the cultured supernatants were measured by bio-chemical methods. The mRNA expression of TNF-alpha, IL-6 and Toll-like receptors (TLRs) in cells was detected by reverse transcription polymerase chain reaction (RT-PCR). The expression of TLR2 and TLR4 in peritoneal cells was measured by flow cytometry.
Results: Streptococcal protein significantly enhanced the activities of proliferation and phagocytosis of macrophages (P<0.05), induced the release of IL-6, TNF-alpha and the expression of IL-6, TNF-alpha mRNA (P<0.05).The streptococcal protein, meanwhile, also up-regulated the expression of TLR2 and TLR4 in macrophages in vitro (P<0.05).
Conclusion: Streptococcal protein may promote proliferation, phagocytosis and cytokines production in regulation of the activity of murine macrophages.