MMP-9, MMP-2, and active MMP-9 levels in the plasma of patients with IM. (A) Levels of MMP-9 in the plasma of healthy subjects (n = 25) and patients with IM (n = 45) and PV (n = 20) were assayed by ELISA. Each point represents the mean of the concentration of MMP-9 in each individual plasma sample assayed in duplicate. The bar represents the mean of each sample group. The levels of MMP-9 in the plasma of both patients with IM (P < .001) and patients with PV (P < .001) were significantly greater than that of normal control plasma. There was no significant difference between the levels of MMP-9 in patients with IM and PV (P > .05). (B) Levels of MMP-2 in the plasma of healthy subjects (n = 9) and patients with IM (n = 11) were assayed by ELISA. Each point represents the mean of the concentration of MMP-2 in each individual plasma sample assayed in duplicate. The bar represents the mean of each sample group. There was no significant difference between the levels of MMP-2 in the plasma of healthy subjects and patients with IM (P > .05). (C) Levels of endogenous active MMP-9 in the plasma of healthy subjects (n = 17) and patients with IM (n = 28) and PV (n = 10) were assayed by ELISA. Each point represents the mean concentration of endogenous active MMP-9 in each individual plasma sample assayed in duplicate. The bar represents the mean of each sample group. The levels of endogenous active MMP-9 in the plasma of both patients with IM (P < .01) and patients with PV (P < .01) were significantly greater than that of normal control plasma. There was no significant difference between the levels of endogenous active MMP-9 in patients with IM and PV (P > .05).