Application of Long-term cultured Interferon-γ Enzyme-linked Immunospot Assay for Assessing Effector and Memory T Cell Responses in Cattle.
Effector and memory T cells are generated through developmental programing of naïve cells following antigen recognition. If the infection is controlled up to 95 % of the T cells generated during the expansion phase are eliminated (i.e., contraction phase) and memory T cells remain, sometimes for a lifetime. In humans, two functionally distinct subsets of memory T cells have been described based on the expression of lymph node homing receptors. Central memory T cells express C-C chemokine receptor 7 and CD45RO and are mainly located in T-cell areas of secondary lymphoid organs. Effector memory T cells express CD45RO, lack CCR7 and display receptors associated with lymphocyte homing to peripheral or inflamed tissues. Effector T cells do not express either CCR7 or CD45RO but upon encounter with antigen produce effector cytokines, such as interferon-γ. Interferon-γ release assays are used for the diagnosis of bovine and human tuberculosis and detect primarily effector and effector memory T cell responses. Central memory T cell responses by CD4(+) T cells to vaccination, on the other hand, may be used to predict vaccine efficacy, as demonstrated with simian immunodeficiency virus infection of non-human primates, tuberculosis in mice, and malaria in humans. Several studies with mice and humans as well as unpublished data on cattle, have demonstrated that interferon-γ ELISPOT assays measure central memory T cell responses. With this assay, peripheral blood mononuclear cells are cultured in decreasing concentration of antigen for 10 to 14 days (long-term culture), allowing effector responses to peak and wane; facilitating central memory T cells to differentiate and expand within the culture.
Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture; Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University; mayara.maggioli@ars.usda.gov.
Mayara F
MF
Maggioli
Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture.
Mitchell V
MV
Palmer
UK Veterinary Laboratories Agency.
H Martin
HM
Vordermeier
UK Veterinary Laboratories Agency.
Adam O
AO
Whelan
Visual Services, National Centers for Animal Health, Animal and Plant Health Inspection Service, United States Department of Agriculture.
James M
JM
Fosse
Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture.
Brian J
BJ
Nonnecke
Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture.
W Ray
WR
Waters
D000818:Animals; D002417:Cattle; D016207:Cytokines / Q000276:immunology; D058501:Enzyme-Linked Immunospot Assay; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000276:immunology*; D059425:Interferon-gamma Release Tests; D017493:Leukocyte Common Antigens / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D054400:Receptors, CCR7 / Q000378:metabolism; D016201:Receptors, Lymphocyte Homing; D013601:T-Lymphocytes / Q000276:immunology*; D014380:Tuberculosis, Bovine / Q000175:diagnosis*
D016207:Cytokines; D054400:Receptors, CCR7; D016201:Receptors, Lymphocyte Homing; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens