Figure 5.
Mucosal-associated invariant T (MAIT) cells are readily proliferative in response to E. coli and maintain a highly cytotoxic profile. Peripheral blood mononuclear cells (PBMCs) from healthy donors were CellTrace Violet (CTV)-labeled and cultured with paraformaldehyde (PFA)-fixed E. coli for 6 days. BpC=bacteria per cell ratio. (a) Representative plot showing dilution of CTV against CD161 expression (upper panel) and Vα7.2 expression (lower panel) at 10 BpC or with anti-CD3/CD28/CD2 beads, gated on CD8+ T cells. (b) Cumulative data (left) and representative flow cytometry histograms are shown for each BpC. One-way analysis of variance (ANOVA), with Bonferroni's multiple comparisons test. (c) Representative plot (left) and cumulative data (right) showing Ki67 staining in CD8+ T cells after E. coli-stimulation at 10 BpC (n=4). (d) Proliferation of Vα7.2+CD161++CD8+ T cells in response to E. coli with anti-MR1, interleukin (IL)-12, and IL-18-blocking antibodies at the indicated BpCs. Results pooled from two independent experiments and analyzed by two-way ANOVA, with Bonferroni's multiple comparisons test. (e) GrB and perforin, and (f) GrA and GrK expression in CTV-labeled Vα7.2+CD161++CD8+ T cells following E. coli stimulation for 6 days. Cumulative data (left) and representative staining is shown (right). Gating for granzymes and perforin based on isotype controls. Results analyzed by paired t-test (n=8). Bars indicate mean±s.e.m. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001.