TLR8 agonists induce profound and prolonged degradation of IκB-α. Purified neonatal or adult monocytes were cultured in 100% autologous serum and incubated for the indicated number of minutes with buffer control (ie, unstimulated, U) or with 50 μM of the pure TLR7 agonist 3M-013 (7) or the pure TLR8 agonist 3M-002 (8) prior to lysis in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) buffer, electrophoresis, and Western blotting for IκB-α. Autoradiograms were scanned and digital intensity analyzed as described in “Materials and methods.” Representative autoradiograms are shown in panels A and B. Composite densitometric analysis expressed as a stimulation index (ie, density of IκB-α in the stimulated condition divided by that in the unstimulated condition) demonstrates that whereas TLR7 agonist-induced degradation of IκB-α in neonatal monocytes was of modest extent (∼50%) and duration (< 60 minutes; C), TLR8 activation was associated with profound (∼90%) and prolonged (≥ 60 minutes) disappearance of IκB-α (D). Statistical comparisons are made within groups (□, newborns; ▪, adults) in relation to the unstimulated condition (defined as 1.0). n = 4, *P < .05; **P < .01, ***P < .001.