Lung CD4-CD8- double-negative T cells are prominent producers of IL-17A and IFN-gamma during primary respiratory murine infection with Francisella tularensis live vaccine strain.
For several intracellular infections, pulmonary vaccination provides measurably better protection against pulmonary challenge. The unique factors that contribute to pulmonary immune responses are not well characterized. In this study, we show that CD4(-)CD8(-) double negative (DN) T cells are a major responding T cell subset in the lungs of mice during pulmonary Francisella tularensis live vaccine strain (LVS) infection. DN T cells were a minor (<2%) subset in spleens and lungs of mice during sublethal intradermal infection with LVS. In contrast, they were a major responding T cell subset in lungs during pulmonary LVS infection, producing large quantities of IFN-gamma and IL-17A. The numbers of IL-17A(+) DN T cells in the lungs exceeded that of CD4(+) and CD8(+) T cells on day 7 postinfection; by day 14 postinfection, all three IL-17A-producing T cell subsets were present in equivalent numbers. CD4(+), CD8(+), and DN T cell production of IL-17A was not observed in the spleens of pulmonary-infected mice or the lungs and spleens of intradermally infected mice. Correspondingly, IL-17A knockout mice were more susceptible to respiratory than intradermal LVS infection, with delayed clearance 1-3 wk postinfection. Finally, in vitro treatment of LVS-infected macrophages and alveolar type II epithelial cells with IFN-gamma and IL-17A affected significantly greater LVS growth control than treatment with either cytokine alone. The data presented in this study demonstrate that DN cells contribute to production of IL-17A and IFN-gamma in the lungs during inhalational Francisella infection and that these cytokines additively activate host cells to control LVS intracellular growth.
Cowley
Siobhán C
SC
Division of Bacterial, Parasitic and Allergenic Products, Laboratory of Mycobacterial Diseases and Cellular Immunology, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Rockville, MD 20852, USA. siobhan.cowley@fda.hhs.gov
Meierovics
Anda I
AI
Frelinger
Jeffrey A
JA
Iwakura
Yoichiro
Y
Elkins
Karen L
KL
D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D015704:CD4 Antigens / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018920:Coculture Techniques; D005604:Francisella tularensis / Q000254:growth & development / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D020381:Interleukin-17 / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics; D016676:Macrophages, Alveolar / Q000276:immunology / Q000382:microbiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018410:Pneumonia, Bacterial / Q000276:immunology* / Q000382:microbiology; D020545:Respiratory Mucosa / Q000276:immunology / Q000382:microbiology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000382:microbiology; D014406:Tularemia / Q000276:immunology / Q000382:microbiology
D001428:Bacterial Vaccines; D015704:CD4 Antigens; D016827:CD8 Antigens; C098680:Il17a protein, mouse; D020381:Interleukin-17; D007371:Interferon-gamma