Objective: Gramzyme A (GrA) is a serine proteinase with trypsin-like activity that is released extracellularly during the degranulation of cytotoxic cells. Among the cytotoxic cells, gamma/delta T cells participate in the early phases of the immune response and are known to express perforin and granzymes constitutively in agreement with their cytolytic pontential.
Methods: GrA activity was detected using the synthetic substrate N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester in the plasma and supernatants of peripheral blood mononuclear cell cultured in the presence of Dimethylallyl pyrophosphate to obtain Vgamma9/Vdelta2 T cell expansion.
Results: Significantly high levels of GrA were found in the serum and supernatants of lymphocytes from patients with active Behçet's disease cultured in the presence of DMAPP. Levels were found to be significantly lower after remission. A positive correlation was observed between GrA levels in the supernatants and the Vgamma9/Vdelta2 T cell expansion factor.
Conclusion: These results strongly suggest that Vgamma9/Vdelta2 T cells are active participants in the pathogenesis of the disease through their degranulation and granzyme release.