Figure 3: T-cell activation by NAs complexed with antimicrobial peptides or core histones.

(a,b) Naive CD4⁺ T cells derived from WT and Myd88^−/− mice were stimulated with plate-bound anti-CD3∈ together with calf thymus (CT)- or E. coli (EC)-derived genomic DNA (a) or RNAs (b) either alone or premixed with LL37. After 48 h, IL-2 production and cell growth were assessed by ELISA and MTS assay, respectively. *P<0.05, Student’s t-test (compared with anti-CD3 plus LL37 in WT cells). (c) Naive CD4⁺ T cells were incubated with the Cy5-labelled CT DNA premixed with the indicated histones or LL37 at 37 °C for 90 min and the incorporated DNA were analysed by flow cytometry. (d,f) Naive CD4⁺ T cells derived from WT and Myd88^−/− Trif^−/− mice were stimulated with plate-bound anti-CD3 together with CT DNA alone (d), RNAs alone (f) or premixed with various histones (d,f), and analysed similarly in (a). *P<0.05, Student’s t-test (compared with anti-CD3 plus each histone or LL37 in WT cells). (e) Naive CD4⁺ T cells were stimulated with anti-CD3 with Cy5-labelled CT DNA premixed with Alexa488-labelled histone H3 for 18 h. Endosomes and Lysosomes were visualized by staining with dextran-Alexa Fluor 488 and LysoTracker, respectively. Confocal and differential interference contrast (DIC) images of representative cells are shown. Scale bars, 2.5 μm. Error bars indicate s.d. Data are representative of at least two independent experiments.