S100A9 and idiopathic pulmonary fibrosis: Although individuals of delta mean fluorescent intensity (M.F.I) of CD163 and S100A9 showed similar trends between classical and non-classical monocytes, the individual delta M.F.I of S100A9 and CD163 in classical monocytes but not that in non-classical monocytes showed a significant increase in iNSIP as compared to IPF patients (p < 0.05 and p < 0.05).