Effects of pyocyanine, a blue pigment from Pseudomonas aeruginosa, on separate steps of T cell activation: Interleukin 2 (IL 2) production, IL 2 receptor formation, proliferation and induction of cytolytic activity

Abstract

Pyocyanine was isolated by chloroform extraction of cultures of Pseudomonas aeruginosa, and purified by thin layer chromatography. The effects of pyocyanine on the various stages of T cell activation were studied with concanavalin A-stimulated CBA/J mouse splenocyres. At 12.5 μM concentration pyocyanine totally inhibited Con A-dependent prolifzration and development of cytotoxic effector cells. Protein and RNA synthesis was only 50% inhibited at this concentration. Inhibitory doses of pyocyanine were nontoxic, in that cell viability was maintained, and the inhibitory effects were reversible after removal of the drug. Pyocyanine did not interfere with interleukin 2 synthesis, nor did it affect the lytic stage of cytotoxic effector T cells. However, T blasts generated by Con A in the presence of pyocyanine did not grow in response to IL2 even in the absence of pyocyanine, and IL2 receptors, detected by indirect immunofluorescence with the receptor-specific monoclonal antibody AMT-13, were diminished in pyocyanine-treated cells. Pyocyanine also inhibited IL2-dependent proliferation of T blasts with fully developed IL2 receptors. The substance thus interferes with several discrete stages of T cell activation.