MHC Class Ib-Restricted CD8 T Cells Differ in Dependence on CD4 T Cell Help and CD28 Costimulation over the Course of Mouse Polyomavirus Infection

Abstract

We recently identified a protective MHC class Ib-restricted CD8 T cell response to infection with mouse polyomavirus. These CD8 T cells recognize a peptide from aa 139–147 of the VP2 viral capsid protein bound to the nonpolymorphic H-2Q9 molecule, a member of the Qa-2 family of β2m-associated MHC-Ib molecules. Q9:VP2.139-specific CD8 T cells exhibit an unusual inflationary response characterized by a gradual expansion over 3 months followed by a stable maintenance phase. We previously demonstrated that Q9:VP2.139-specific CD8 T cells are dependent on Ag for expansion, but not for the long-term maintenance. Here, we tested the hypothesis that the expansion and maintenance components of the Q9:VP2.139-specific T cell response are differentially dependent on CD4 T cell help and CD28 costimulation. Depletion of CD4+ cells and CD28/CD40L blockade impaired expansion of Q9:VP2.139-specific CD8 T cells, and intrinsic CD28 signaling was sufficient for expansion. In contrast, CD4 T cell-insufficiency, but not CD28/CD40L blockade, resulted in a decline in frequency of Q9:VP2.139-specific CD8 T cells during the maintenance phase. These results indicate that the Q9:VP2.139-specific CD8 T cell response to mouse polyomavirus infection depends on CD4 T cell help and CD28 costimulation for inflationary expansion, but only on CD4 T cell help for maintenance.

Peptide Immunization Elicits Polyomavirus-Specific MHC Class Ib-Restricted CD8 T Cells in MHC Class Ia Allogeneic Mice

“…In B6 mice, NKG2A is the predominant NKG2 isoform expressed by this heterodimeric receptor (36), and has been interpreted as a T cell activation marker (16,18,19). These data are consistent with our previous observations that CD94-NKG2A expression increases while CD28 expression decreases on Q9:VP2.139-specific CD8 T cells over the course of MPyV infection (11).…”

“…Single cell suspensions of RBC-lysed splenocytes prepared from each of these mice were incubated with or without 10 mM VP2.139 peptide for 5 h in the presence of Brefeldin A (GolgiPlug, BD Bioscience). Cells were surface stained, then permeabilized (Cytofix/ Cytoperm, BD Bioscience) and stained intracellularly, as previously described (11). Alternatively, RBC-lysed splenocytes were treated with FcBlock (BD Biosciences) then co-stained with tetramers (described below) and antibodies, as previously described (11).…”

“…Cells were surface stained, then permeabilized (Cytofix/ Cytoperm, BD Bioscience) and stained intracellularly, as previously described (11). Alternatively, RBC-lysed splenocytes were treated with FcBlock (BD Biosciences) then co-stained with tetramers (described below) and antibodies, as previously described (11). Samples were run on BD FACSVerse (BD Biosciences).…”

αβT Cell Receptors Expressed by CD4−CD8αβ− Intraepithelial T Cells Drive Their Fate into a Unique Lineage with Unusual MHC Reactivities

“…First, this strategy has been proven reliable (Alli et al, 2008; Arnold et al, 2004; Hofstetter et al, 2012; Lathrop et al, 2011) and it allowed us to compare several cloned TCRs in parallel. More importantly, each TCR could be analysed directly in several recipients with various genetic deficiencies in antigen presenting molecules without the need for laborious backcrossing of TCR transgenes.…”

Class II MHC/Peptide Interaction in Leishmania donovani Infection: Implications in Vaccine Design

“…Thus, an MHC-II-restricted immune response is most likely essential to control infection. The importance of CD4 + T cells in helping the expansion of CD8 + T cells has been well studied in viral infection in mice in whom CD8 + T cell expansion may be CD4 + T cell dependent (19)(20)(21)(22) or independent (23). MFs infected with Leishmania amazonensis display normal levels of MHC-II, but Ag presentation may be inhibited by inefficient loading of peptide to MHC-II (24).…”