title: Alteration of murine immune response by Pseudomonas aeruginosa exotoxin A.
abstract: Pseudomonas exotoxin A has been implicated as a possible virulence factor in Pseudomonas infections. This toxin has a direct cytotoxic effect on a number of cell types, including macrophages and their precursors, and therefore may affect other cells of the immune system. NFR/N(H-2q) (+/nu or nu/nu) mice were immunized with either T-dependent or T-independent antigens along with various doses of exotoxin A. The immune response was then assayed by a modification of the Jerne plaque assay. Exotoxin A induced a dose-dependent suppression of the in vitro and in vivo immune responses to T-dependent and T-independent antigens in immunocompetent +/nu mice. However, in NFR/N nu/nu mice, suppression of the immune response to the T-independent antigen trinitrophenylated-Ficoll was not observed. Instead, a marked enhancement of the response was observed at doses of 100 and 10 ng of exotoxin A. Removal of T-cells with anti-Thy 1.2 antiserum plus complement before antigen and exotoxin A stimulation in +/nu mice results in abrogation of the suppression. These data suggest that Pseudomonas exotoxin A exerts an effect on both B- and T-lymphocyte populations to modulate the immune response and that this activity may be one facet of the pathogenic effects of this toxin.
mesh_terms: D036002:ADP Ribose Transferases; D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D001427:Bacterial Toxins; D004261:DNA Replication; D005098:Exotoxins / Q000276:immunology* / Q000633:toxicity; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D011552:Pseudomonas Infections / Q000276:immunology*; D011550:Pseudomonas aeruginosa / Q000276:immunology* / Q000472:pathogenicity; D013601:T-Lymphocytes / Q000276:immunology; D014774:Virulence; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D005098:Exotoxins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A