Cytotoxic CD4+ T cells specific for Francisella tularensis.
The specific cell-mediated cytotoxicity of tularaemia-immune human T lymphocytes were studied in vitro. Peripheral blood mononuclear cells (PBMC) of six tularaemia-vaccinated healthy subjects were stimulated with F. tularensis LVS whole cell antigen for 6 days and used as effector cells in a conventional 4-h 51Cr release cytotoxicity assay. The target cells were phagocyting autologous monocytes, which were pulsed with F. tularensis or PPD antigen. The specific lysis of the F. tularensis-pulsed cells (42.6% +/- 11.7) was significantly higher (P less than 0.05) than that of the PPD-pulsed ones (22.2% +/- 8.3) or unpulsed control cells (15.9% +/- 5.2). The cytotoxicity was associated with CD4+ F. tularensis-specific T cell clones (TLC), which killed 36.3% +/- 12.3 of the F. tularensis-pulsed targets but only 6.9% +/- 6.5 of the unpulsed control targets. Their lysing was inhibited by monoclonal anti-HLA-DR and anti-HLA-DQ antibodies, but not by CD15 (monocyte/macrophage) antibody. The functional role of CD4+ lymphocytes in tularaemia immunity is discussed.
Surcel
H M
HM
National Public Health Institute, Oulu, Finland.
Tapaninaho
S
S
Herva
E
E
D000911:Antibodies, Monoclonal / Q000276:immunology; D015704:CD4 Antigens; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D005604:Francisella tularensis / Q000276:immunology*; D006650:Histocompatibility Testing; D006801:Humans; D016130:Immunophenotyping; D009000:Monocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens