FIGURE 2.

Gremlin-1 inhibits monocyte differentiation into macrophages. a, macrophages/foam cells were differentiated from monocytes as described (30). The formation of macrophages/foam cells was evaluated over time through cell counting in the presence of Gremlin-1/Drm (1 μg/ml), Gremlin-2/PRDC (1 μg/ml), or the unspecific IgG (1 μg/ml) control. Representative photomicrographs are shown from five independent experiments. Data represent the mean ± S.E. (**, p < 0.01). b, macrophages/foam cells were differentiated from monocytes as described (30). 36 cytokines and chemokines were analyzed in the supernatant of this culture when most monocytes had differentiated into macrophages and foam cells (human cytokine array kit, R&D Systems). Expressions are shown as the density of the immunoreactive spots minus the base-line density of the gel. Among the analyzed factors MIF was prominently expressed in the macrophage/foam cell culture, indicating the central function of MIF in the differentiation of monocytes to macrophages and foam cells. c, the effect of MIF (10 ng/ml) compared with control diluent on monocyte/macrophage differentiation was evaluated. Data represent the mean ± S.E. of three independent experiments (**, p < 0.01). d, anti-MIF mAb (25 μg/ml) and IgG control (25 μg/ml) were analyzed regarding their effect on monocyte/macrophage differentiation. Data represent the mean ± S.E. of three independent experiments (*, p < 0.05).