Consistent with enrichment analyses, immunohistochemistry reveals increased pSTAT3 expression in the interfollicular space of iMCD lymph node tissue. (A) iMCD demonstrated significantly more positive staining for pSTAT3 in the interfollicular space compared with normal lymph nodes (P = .0037). No significant differences were observed in germinal centers (P = .2610), secondary follicles (P = .4119), and mantle zones (P = .552). (B) Within the interfollicular space, iMCD lymph nodes demonstrated significantly higher weak (P = .014) and medium (P = .0066) with no difference in strong staining intensity. Representative images of a normal lymph node (C) and an iMCD lymph node (D) (40× magnification) are provided.