Human gammadelta T cells produce the protease inhibitor and antimicrobial peptide elafin.

Human gammadelta T cells rapidly secrete pro-inflammatory cytokines in response to T cell receptor-dependent recognition of pyrophosphates produced by many bacteria and parasites. In further support of an important role of gammadelta T cells in the immune defence against infection, human gammadelta T cells have been shown to produce the antimicrobial peptide LL37/cathelicidin. In this study, we have investigated whether gammadelta T cells can produce additional antimicrobial peptides. To this end, we have screened human gammadelta T cell clones by RT-PCR for mRNA expression of a broad range of antimicrobial peptides. While alpha-defensins were absent and beta-defensins (HBD1) present only in rare gammadelta T cell clones, elafin mRNA was induced by supernatant of Pseudomonas aeruginosa grown under static conditions. Elafin is a protease inhibitor that also displays antimicrobial activity. Constitutive intracellular expression of elafin was demonstrated by flow cytometry and Western blot analysis. Furthermore, trappin-2 (pre-elafin) could be immunoprecipitated in cell lysates but also in the supernatant of gammadelta T cells stimulated by Ps. aeruginosa supernatant. Taken together, our studies reveal a novel effector function of gammadelta T cells which might be important for local immune defence.