S100A9 and idiopathic pulmonary fibrosis: Univariate regression analysis showed that the percentages of S100A9+ cells (Gate 1 + 2), S100A9+CD163− cells (Gate 1), and S100A9−CD163+ cells (Gate 4) had statistically significant association with IPF, discriminating it from iNSIP among the four parameters (Table 3).