ABSTRACT
Objective To affirm the expression of Toll like receptor 4 (TLR4) on the surface membrane of platelet and to explore the immunomodulatory factors[(interlukine-8(IL-8),β-thromboglobulin(β-TG), soluble CD40 ligand(sCD40L)] released by platelets after platelets stimulated by TLR4 ligand.Methods TLR4 expressed on the platelet was detected by flow cytometry. Monoclonal anti-human FcγRⅡantibody(Ⅳ.3)-treated human platelets were cultured with LPS in the presence or absence of blocking monoclonal antibody to human TLR4. The release of IL-8, β-TG, sCD40L were measured by specific enzymelinked immunosorbent assay. Results Human platelets could express functional TLR4. The detection rate of TLR4 on platelets were decreased after LPS involvement(P<0.01). It was noted that sCD40L and β-TG were present in large concentration in the release of platelets stimulated by TLR4 ligand but the release of IL-8 was independent of platelet activation after TLR4 engagement. The concentration of sCD40L and β-TG had no statistical difference between 1-5 μg/ml LPS. The effects of LPS on the modulation of secretory factors were attenuated by preincubation of platelets with an anti-TLR4 monoclonal antibody. Conclusion The TLR4 on platelet could recognize and link LPS, induce the release of sCD40L, β-TG by platelet, but could not influence IL-8.