IFNγ inhibits LPS- and PMA-induced MMP expression in primary monocytes. A-C, Primary human monocytes were stimulated with 100 ng/ml of LPS with or without IFNγ pre-treatment (100 U/ml, added 3 hr before LPS) for 3 hr (A and C), or 12 hr (B). D, PMA (100 ng/ml) stimulation of primary monocytes in the absence or presence of IFNγ pre-treatment. mRNA levels were analyzed using real time PCR and normalized relative to β-Actin; results are expressed as mean ± SD of triplicate determinants. Results are shown as expression in stimulated monocytes relative to expression in unstimulated cells (control), which was set at 1.