FIG. 4.

Activation of TLR2 by viruses expressing the WTF-H protein triggers release of IL-6 and expression of CD150 in human monocytes. (a and b) Cells were left untreated (lane 1) or were stimulated with LPS (lane 2), PamCSK (lane 3), mock supernatant (lane 4), ED (lane 5), ED(WTF-F) (lane 6), ED(WTF-H) (lane 7), ED(WTF-H; N→Y) (lane 8), ED(WTF-F/H) (lane 9), or WTF (lane 10). After 12 h, supernatants were harvested for determination of IL-6 (a), while cells were stained for CD150 surface expression (b). Values represent means of seven (a) or four (b) individual donors and were normalized to the IL-6 content of the inoculum (determined on the basis of the medium control; P ≤ 0.01) (a) or to the medium control (P ≤ 0.01) (b). (c and d) Cells (three donors) were pretreated with TLR2-, TLR4-, or CD14-specific antibodies and incubated with PamCSK (2.5, 0.5, and 0.1 μg/ml) (black bars) or WTF (10, 2 or 0.4 μg/ml of purified virus) (white bars). Alternatively, PamCSK or WTF (same concentrations as above) were treated with MV N- or MV H-specific antibodies prior to incubation with monocytes. Release of IL-6 (c) or induction of CD150 (d) was determined, and inhibition by the antibodies used (percent) was determined with respect to the control in the absence of antibody (P ≤ 0.01). Statistically significant differences from the control are indicated by asterisks.