Effect of exogenous IL-10 and anti-IL-10 Ab on IL-12, IL-6, IL-1β, and TNF-α production. Vitamin D3-treated THP-1 cells (106/ml) were incubated with L-OspA (1 μg/ml) in the presence or absence of various concentrations of human rIL-10 and anti-IL-10 Ab (αIL-10). After 48 h, specific cytokines in cell-free supernatants were quantified by Ab capture ELISA. The lower limit of detection of the ELISA was 15 pg/ml. ∗, significantly different from value for cells incubated with L-OspA alone (P < 0. 007, P < 0.04, and P < 0.02 for IL-12, IL-6 and TNF-α, and IL-1β, respectively); ∗∗, significantly different from value for cells incubated with L-OspA alone (P < 0.01). P values were calculated by use of Student's t test. Each bar represents the mean ± standard deviation for duplicate cultures. Data are representative of those from three and two separate experiments for rIL-10 and anti-IL-10, respectively.