Live mf of B malayi do not trigger TLR3 or TLR4 signaling pathways. (A) HEK293 cells transfected with different TLR (HEK293 cells endogenously express TLR5; no TLR is TLR5) were stimulated for 24 hours with 100 ng/mL flagellin (for “no TLR” to test TLR5), 2 μg/mL poly I:C, 100 ng/mL LPS, 1 μg/mL Pam3Cys or live mf at 2500 or 25 000 per well. Data are expressed as luciferase units. (B,C) Percentage inhibition of cytokines was calculated in 48-hour mf-exposed DCs with or without α-TLR2 antibody and compared with unexposed DCs. All cultures were then activated with either (B) poly I:C or (C) LPS for 72 hours. Cytokines shown (IFN-α, IL-12p40, IL-12p70, MIP-1α, and IL-1α for poly I:C activation and IL-12p40 for LPS activation) are the cytokines significantly down-regulated in mf-exposed DCs (Figure 2A,B). Data shown as bar graphs of 3 to 4 independent experiments with means and standard error of the mean.
