Identification of the principal T lymphocyte-stimulating antigens of Pseudomonas aeruginosa

To aid in understanding the role of cellular immunity in limiting Pseudomonas aeruginosa infections, we have identified some of the principal antigens of the organism that are recognized by human T cells. Clones of T cells were selected in such a manner that they would provide information not only about the identity of Pseudomonas antigens, but also the T cell repertoires of immune donors. Most clones were found to be specific for Pseudomonas alkaline protease (AP). Such clones could be physically isolated by selecting with crude Pseudomonas antigens or purified AP. In either case, their fine specificities were the same when tested against a panel of Pseudomonas antigens. The conclusion that AP is the principal immunogen for many donors was confirmed by measuring the absolute frequencies of proliferating T cells committed to AP and all other Pseudomonas antigens. Frequencies of AP-specific clones (1.5-2.7 X 10(-5] were comparable to those from the same donors that were specific for all secreted Pseudomonas antigens (1.3-6.0 X 10(-5]. These results provide a model system for studying human T cell-mediated immunity to bacteria by identifying discrete antigens and measuring the repertoire diversities of cells responding to them.