ELISA assays for production of IL-6 in human microglia. PAF (at 100 nM) induced no significant production of IL-6 from microglia following exposures from 1–24 h (n = 4 for each time points). PAF (at 1 μM) induced no significant production of IL-6 (following exposures for 8 h and 24 h; n = 3 for both time points); these values are near the lower limits for sensitivity of the ELISA kits. LPS was used as a positive control in these experiments (n = 4); note the change of scale for the ordinate (from 10 to 400 pg/ml). * P < 0.05 compared with unstimulated control.