title: Differences in maintenance of CD8+ and CD4+ bacteria-specific effector-memory T cell populations.
abstract: Our knowledge about the kinetics and dynamics of complex pathogen-specific CD8(+) T cell responses and the in vivo development of CD8(+) memory T cells has increased substantially over the past years; in comparison, relatively little is known about the CD4(+) T cell compartment. We monitored and directly compared the phenotypical changes of pathogen (Listeria monocytogenes)-specific CD8(+) and CD4(+) T cell responses under conditions leading to effective and long-lasting protective immunity. We found that the general kinetics of bacteria-specific CD8(+) and CD4(+) T cells during the effector and post-effector phases are synchronized. However, later during the memory phase, CD8(+) and CD4(+) T cell populations differ substantially. Whereas CD8(+) memory T cell populations with immediate effector function are readily detectable in lymphoid and non-lymphoid tissues and remain remarkably stable in size, antigen-specific CD4(+) effector-memory T cells decline continuously in frequency over time. These findings have important implications for the better understanding of the in vivo development of protective immunity towards intracellular pathogens.
mesh_terms: D000818:Animals; D001427:Bacterial Toxins; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte; D006360:Heat-Shock Proteins / Q000276:immunology; D006460:Hemolysin Proteins; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D008089:Listeria monocytogenes / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D001427:Bacterial Toxins; D018984:Epitopes, T-Lymphocyte; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; C038705:hlyA protein, Listeria monocytogenes