The relationship between human effector and memory T cells measured by ex vivo and cultured ELISPOT following recent and distal priming

Immunology. 2009 Sep;128(1):83-91. doi: 10.1111/j.1365-2567.2009.03073.x.

Abstract

Maintenance of T-cell responses is an essential feature in protection from many infectious diseases that must be harnessed in vaccination. The relationship between effector T-cell responses and more durable and highly proliferative T-cell memory, particularly in humans, is not well understood. In this study, effector T-cell responses were measured by overnight ex vivo interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot-forming cell assay (ELISPOT), whereas memory T cells were measured by 10-day culture followed by IFN-gamma ELISPOT (cultured ELISPOT). We observed a significant correlation between IFN-gamma responses to CD4-stimulatory, but not to CD8-stimulatory, recall antigens measured by these assays, suggesting a divergence in regulation. In vaccine trial participants who received a prime-boost vaccination regimen comprising malaria antigens delivered by poxviruses, there was a correlation between ex vivo and cultured responses on day 7, but not 3 months post-vaccination, with the ratio of cultured : ex vivo response increasing over time. To compare responses revealed by cultured ELISPOT in more detail, tetramers comprising viral recall antigens were used to ascribe effector-memory and central-memory T-cell phenotypes through CCR7 and CD62L costaining. For CD8(+) responses the effector phenotype decreased during the initial culture period and memory populations remained high within the resulting 20-fold to 50-fold increased IFN-gamma-secreting or tetramer(+) population. This was less marked for CD4(+) responses, which had higher starting memory phenotype. Depletion of these central-memory T-cell populations generally ablated responses in cultured ELISPOT and reduced ex vivo responses. This study highlights differences between CD4(+) and CD8(+) effector and memory T cells, and the more complex phenotype of CD4(+) T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • CD4-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / immunology*
  • Cells, Cultured
  • Enzyme-Linked Immunosorbent Assay / methods
  • Humans
  • Immunologic Memory / immunology
  • Immunophenotyping
  • Interferon-gamma / biosynthesis
  • Interleukin-2 / biosynthesis
  • Malaria Vaccines / immunology
  • Middle Aged
  • Tuberculin / immunology
  • Vaccination
  • Young Adult

Substances

  • Interleukin-2
  • Malaria Vaccines
  • Tuberculin
  • Interferon-gamma