FIGURE 4.

Role for IL-6 in negative regulation of neutrophil recruitment in cocultures. (A) Detection of IL-6 in supernatants of GEnC and podocyte cocultures (▴) and monocultures of GEnC (▪) and podocytes (●) that were treated with and without TNF-α. Data are means ± SEM (n = 4). Two-way ANOVA shows a significant effect of cytokine treatment on IL-6 production (p < 0.05). *p < 0.05 comparing IL-6 production between cocultures and GEnC monocultures by a Bonferroni post hoc test. (B) Neutralization of IL-6 in cultures by incorporation of 5 μg/ml anti–IL-6 Ab (labeled as IL-6 block) into TNF-α (100 U/ml)–stimulated cultures for 24 h starting from the time of establishing the cocultures. Neutrophil recruitment was assessed at 1 h and is expressed as percentage of cells recruited. Data are represented as minimum to maximum levels of recruitment (n = 5). The effects were compared with an isotype-matched mouse IgG in these experiments. *p < 0.05, **p < 0.001 comparing the effect of IL-6 neutralization with controls by a paired t test. (C) Recapitulation of coculture by addition of exogenous IL-6 in GEnC monocultures (n = 4). *p < 0.05 by Mann–Whitney U test when comparing treatments, ***p < 0.0001 comparing the effect of cytokine treatment by a paired Wilcoxon signed-rank test between treatments within cultures, ***p < 0.0001 comparing the effect of cytokine treatment by a paired Wilcoxon signed rank test between treatments within cultures.