Recombinant Pseudomonas exoenzyme S and exoenzyme S from Pseudomonas aeruginosa DG1 share the ability to stimulate T lymphocyte proliferation

Exoenzyme S from P. aeruginosa DG1 and recombinant exoenzyme S derived from strain 388 have distinct characteristics, which has led to a controversy a bout their homology and their pathophysiologic consequences. We have been i nvestigating the ability of exoenzyme S to activate T lymphocytes, and ther efore performed studies to determine whether exoenzyme S from P. aeruginosa DG1 and recombinant exoenzyme S derived from strain 388 and expressed in P seudomonas aeruginosa PA103 or in E. coli BL21(DE3), could induce T lymphoc yte activation and proliferation. Both preparations were able to activate T cells and induce lymphocyte proliferation at similar levels as measured by flow cytometry of surface-activation markers and DNA synthesis, respective ly. Further, a monoclonal antibody raised against exoenzyme S from strain D G1 partially neutralized T cell activation induced by recombinant exoenzyme S and bound to it in an immunoblot suggesting that the epitope responsible for T cell activation is shared by exoenzyme S from strain DG1 and recombi nant exoenzyme S. These data suggest that the two different preparations of exoenzyme S, despite biochemical differences, share the characteristic tha t is responsible for T lymphocyte activation.