Journal: Nature Communications
Article Title: MAIT cells protect against pulmonary Legionella longbeachae infection
doi: 10.1038/s41467-018-05202-8
Figure Lengend Snippet: Human MAIT cells are activated by Legionella infection via MR1 in vitro. a Jurkat.MAIT and C1R.MR1 cells were co-incubated for 16 h with lysates of L. pneumophila (L. pn.) or L. longbeachae or 5-OP-RU, acetyl-6-formylpterin (Ac-6-FP) or PBS. Activation, detected by staining with anti-CD69, is enhanced by bacterial lysate or by the activating ligand 5-OP-RU, but not by acetyl-6-FP. Activation was blocked by anti-MR1 antibody (26.5) but not by isotype control (W6/32) 2 h prior to co-incubation. Experiment performed in triplicate wells on two separate occasions with similar results. Data show mean fluorescence intensity, MFI (±SEM). Statistical tests: one-way ANOVA and post hoc Dunnett’s comparing all columns with the first column (black). Unpaired t -test (blue), with *** P < 0.001; **** P < 0.0001. b , c THP1 cells (WT) or THP1 cells overexpressing MR1 (THP1.MR1+, purple) or deficient in expression of MR1 (THP1.MR1−, blue) were infected for 27 h with live or heat-killed (HK) L. longbeachae (MOI: 100) or 10 nM 5-OP-RU, then co-cultured for 16 h with sorted CD3 + Vα7.2 + CD161 + human peripheral blood MAIT cells, or MAIT-depleted conventional T cells. MR1-5-OP-RU-tetramer+ MAIT cell activation was measured by intracellular cytokine staining for b TNF or c IFN-γ. b , c Percentage cytokine-positive cells as mean (±SEM) data from three independent donors performed on two separate occasions are shown. Statistical tests: unpaired t- tests with Bonferroni corrections, each comparing against MOI 0 for the specific cell line. Statistics with * P < 0.05; ** P < 0.01. d Immunofluorescence micrographs showing CD3+TCRVα7.2+ MAIT cell (white arrow) within healthy human lung tissue (top panel) and 24 h post infection (bottom panels) ex vivo with L. longbeachae . Yellow arrow: intracellular L. longbechae bacilli. Red, TCRVα7.2; green, CD3; magenta, polyclonal rabbit anti -L. longbeachae ; blue, nuclei (Hoechst)
Article Snippet: Supernatants were used to transduce parent THP1 cells (ATCC TIB-202, ATCC) and cells were selected using puromycin resistance and single-cell sorting using anti-MR1 antibody (8F2.F9) after upregulation of MR1 using acetyl-6-FP.
Techniques: Infection, In Vitro, Incubation, Activation Assay, Staining, Control, Fluorescence, Expressing, Cell Culture, Immunofluorescence, Ex Vivo