Immunostaining of CX₃CL1 and CX₃CR1 in SSc-ILD.

CX₃CL1 protein is produced from the epithelium and infiltrating interstitial leukocytes in SSc-ILD, while its receptor CX₃CR1 is localized to infiltrating mononuclear cells. Representative histopathological staining of (n = 5) SSc-ILD for CX₃CL1 from (A) Type 2 pneumocytes, (B) Airway epithelium, (C) Epithelium involved in bronchiolization, and (D) Infiltrating mononuclear cells. Representative histopathological staining of (n = 5) SSc-ILD for CX₃CR1 from (E) Infiltrating interstitial mononuclear cells, (F) Morphologically from plasma cells via their eccentric cartwheel nuclei, (G) Representative staining of plasma cell marker CD138 confirming that the cells with eccentric cartwheel nuclei are plasma cells, (H) Representative immunofluorescence staining of plasma cell (red) in the interstitium, CX₃CR1 positive infiltrating mononuclear cells, and co-localization of CD138⁺ plasma cell expressing CX₃CR1 and infiltrating the interstitium.