FABP4 and chronic obstructive pulmonary disease: In a research investigation involving 18 patients diagnosed with COPD and 28 control subjects, the monocytes/macrophages present in the pulmonary tissues of the participants were observed to be classified into 16 distinct sub-populations, among these sub-populations, three primary classes of monocyte/macrophage populations were found to be prevalent in individuals with COPD, including elevated expression levels of FABP4, CD52, and IL-1β respectively, implying a severe inflammatory reaction 82.