Moreover, the results of our mediation analysis supported the mediating effects of perfluoro octane sulfonate (PFOS, a plasma metabolite), IgD–CD27–B cells, CD62L-DCs, HLA DR++ monocytes, HLA DR+ natural killer cells, and CD16 on CD14+ CD16+ monocytes (five immunophenotypes), and CD40L receptor (an inflammatory protein) on gut or skin microbiota in asthma pathogenesis. Here, CD40 is linked to asthma.