¹ Allergy and Inflammation Research Institute, The Key Immunopharmacology Laboratory of Guangdong Province, Shantou University Medical College, Shantou, China

Correspondence: Professor Shaoheng He, Allergy and Inflammation Research Institute, Guangdong Province, Shantou University Medical College, 22 Xin-ling Road, Shantou 515041, China. Email: shoahenghe@hotmail.com

Received 15 November 2005; Accepted 10 April 2006.

Abstract

Proteinase-activated receptors (PAR) have been recognized as playing an important role in inflammation and immune response. However, little is known of the expression and function of PAR on human T cells. In this study, the expression of PAR on highly purified human T cells was determined and the secretion of IL-6 from cultured T cells in response to serine proteinases and agonist peptides of PAR was examined. The results showed that T cells express PAR-1, PAR-2 and PAR-3 proteins and genes. Thrombin, trypsin and tryptase, but not elastase, were able to stimulate concentration-dependent secretion of IL-6 from T cells following a 16 h incubation period. The specific inhibitors of thrombin, trypsin and tryptase inhibited the actions of these proteinases on T cells, indicating that the enzymatic activity is essential for their actions. Agonist peptides of PAR SFLLR-NH₂, TFLLRN-NH₂ and SLIGKV-NH₂, but not TFRGAP-NH₂, GYPGQV-NH₂ and AYPGKF-NH₂, are also capable of inducing IL-6 release from T cells. In conclusion, induction of IL-6 secretion from T cells by thrombin, trypsin and tryptase is probably through the activation of PAR, suggesting that serine proteinases are involved in the regulation of immune response of the body.