Figure 1.

Direct co-stimulation of pre-sensitized T cells via Toll-like receptor (TLR)-2. (a) Unselected splenocytes or fluorescence-activated cell sorting (FACS)-sorted T cells were cultivated on anti-hamster (ha)IgG plus anti-CD3 (3 ng per well) or anti-haIgG coated plates (control) in the presence or absence of Lip-OspA, Met-Asp-Pro (MDP)-OspA (10 μg/ml each), recombinant interleukin-2 (rec. IL-2; 50 U/ml) or lipopolysaccharide (LPS; 1 μg/ml) for 72 h. Proliferation of cells was measured by [³H]thymidine incorporation. Means ± SEM for six different wells are given. Asterisk denotes significant difference (P < 0.05) from control (anti-haIgG or anti-CD3 without supplements). One representative experiment is shown. (b) FACS-sorted T cells were stimulated with anti-CD3 (3 ng per well) and different amounts of Lip-OspA or MDP-OspA (10, 1 or 0.1 μg/ml each) or with 50 U/ml recombinant IL-2. Proliferation of cells was measured by [³H]thymidine incorporation. Means ± SEM for six different wells are given. Asterisk denotes significant difference (P < 0.05) from control (anti-CD3 without supplements). (c) Analysis of splenocytes from C57BL/6 (B6; wild-type), TLR-2^-/- and TLR-4^def C57BL/10ScNCr mice for different cell populations before and after FACS sorting for T cells (re-analysis). CD11c⁺ and I-A⁺ are, in combination, characteristic markers for dendritic cells. Data are given in percentages.