Fig. 4

Stone particles induce sample- and concentration-dependent increases of pro-inflammatory cytokines in THP-1 macrophages. THP-1 macrophages were exposed to 0–400 μg/mL quartzite, anorthosite, rhomb porphyry, dacite, quartz diorite, hornfels and α-quartz for 24 h. The release of CXCL8 (a and d), IL-1β (b and e) and TNFα (c and f) in the cell culture supernatant was measured by ELISA. Results are presented as mean ± SD (n = 5–6). Area under the curve (AUC) values in (d-f) were calculated from the values in (a-c) for the concentration-range of 0–200 μg/mL, and are presented related to equal mass (white bars) and surface area (grey bars). Statistical significance is based on a two-way ANOVA followed by Dunnet’s post-test (a-c) or a one-way ANOVA followed by Tukey post-test (d-f). Values were log-transformed prior to statistical analysis based on deviation from normality and homoscedasticity. Asterisks (*) indicate statistically significant difference from the respective control (a-c), while a capped line indicates statistically significant difference between samples (d-f)