Toxicity of Pseudomonas aeruginosa exotoxin A for human macrophages

Pseudomonas aeruginosa exotoxin A was toxi in vitro for human peripheral blood macrophages. Cytotoxicity, manifested by morphological evidence of cell death and inhibition of [3H]thymidine uptake, followed exposure to as little as 10 ng of exotoxin per ml for 1 h. In addition, phagocytosis of heat-killed Candida albicans by macrophages exposed to sublethal concentrations of exotoxin was impaired. This cytotoxicity was neutralizable with antiexotoxin serum.