PLoS Pathogens (Apr 2018)

Tissue maintenance of CMV-specific inflationary memory T cells by IL-15.

  • Nicolas S Baumann,
  • Nicole Torti,
  • Suzanne P M Welten,
  • Isabel Barnstorf,
  • Mariana Borsa,
  • Katharina Pallmer,
  • Jennifer D Oduro,
  • Luka Cicin-Sain,
  • Koichi Ikuta,
  • Burkhard Ludewig,
  • Annette Oxenius

DOI
https://doi.org/10.1371/journal.ppat.1006993
Journal volume & issue
Vol. 14, no. 4
p. e1006993

Abstract

Read online

Cytomegalovirus (CMV) infection induces an atypical CD8 T cell response, termed inflationary, that is characterised by accumulation and maintenance of high numbers of effector memory like cells in circulation and peripheral tissues-a feature being successfully harnessed for vaccine purposes. Although stability of this population depends on recurrent antigen encounter, the requirements for prolonged survival in peripheral tissues remain unknown. Here, we reveal that murine CMV-specific inflationary CD8 T cells are maintained in an antigen-independent manner and have a half-life of 12 weeks in the lung tissue. This half-life is drastically longer than the one of phenotypically comparable inflationary effector cells. IL-15 alone, and none of other common γ-cytokines, was crucial for survival of inflationary cells in peripheral organs. IL-15, mainly produced by non-hematopoietic cells in lung tissue and being trans-presented, promoted inflationary T cell survival by increasing expression of Bcl-2. These results indicate that inflationary CD8 T cells are not just simply effector-like cells, rather they share properties of both effector and memory CD8 T cells and they appear to be long-lived cells compared to the effector cells from acute virus infections.