Minocycline reduces LPS-induced IL-6, but not IL-1β, levels in the plasma. Mice were injected i.p. with vehicle or minocycline for three consecutive days. On the third day mice were injected with saline or LPS i.p. IL-1β and IL-6 were determined in plasma collected 4 h later. There was no detectable IL-6 (n.d.) in the plasma of saline-treated mice. Bars represent the mean ± SEM (n = 8). Means with different letters (a, b, or c) are significantly different (P < 0.05) from each other.