Ex Vivo kinetics of early and long-term multifunctional human leukocyte antigen E-specific CD8+ cells in volunteers immunized with the Ty21a typhoid vaccine.
T cells are likely to play an important role in the host defense against Salmonella enterica serovar Typhi, the causative agent of typhoid fever. We have shown that HLA-E can function as a restriction element for S. Typhi-specific CD8(+) T cells. Because of the potential importance of HLA-E-restricted CD8(+) responses in resistance to Salmonella infection, we characterized these responses and investigated their kinetics of appearance and persistence in volunteers immunized orally with the licensed attenuated Ty21a strain typhoid vaccine. Cells were obtained from volunteers before and at days 2, 4, 7, 10, 14, 28, 42, 56, 120, 180, 360, and 720 after immunization. An ex vivo multicolor staining panel including antibodies to CD107a and -b, interleukin-2, gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) was used to functionally assess memory T-cell subsets by flow cytometry. Increases in cytokine-secreting CD8(+) cells were observed in the T effector/memory (T(EM)) and CD45RA(+) T(EM) (T(EMRA)) subsets as early as 4 days after immunization and persisted, particularly in the T(EMRA) subset, up to 2 years after immunization. The majority of HLA-E-restricted CD8(+) cells 28 to 56 days after immunization coexpressed CD107, IFN-gamma, and TNF-alpha, showing characteristic features of multifunctional T cells. In summary, the multifunctionality and longevity of the HLA-E-restricted CD8 responses observed in this study highlight their significance in adaptive immunity to S. Typhi. Finally, this is the first demonstration, in either animals or humans, of the presence of long-term multifunctional HLA-E-restricted CD8(+) cells after immunization.
Salerno-Goncalves
Rosângela
R
Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA. rsalerno@medicine.umaryland.edu
Wahid
Rezwanul
R
Sztein
Marcelo B
MB
D000284:Administration, Oral; D000328:Adult; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology*; D005434:Flow Cytometry; D006680:HLA Antigens / Q000032:analysis*; D015395:Histocompatibility Antigens Class I / Q000032:analysis*; D006805:Human Experimentation; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D052118:Lysosomal-Associated Membrane Protein 1 / Q000032:analysis; D052119:Lysosomal-Associated Membrane Protein 2 / Q000032:analysis; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014435:Typhoid Fever / Q000517:prevention & control*; D014436:Typhoid-Paratyphoid Vaccines / Q000008:administration & dosage / Q000276:immunology*; D000097625:HLA-E Antigens
D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D007371:Interferon-gamma; D007376:Interleukin-2; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D011135:Polysaccharides, Bacterial; D014409:Tumor Necrosis Factor-alpha; D014436:Typhoid-Paratyphoid Vaccines; D000097625:HLA-E Antigens; C072772:Ty21a typhoid vaccine