Fig 2: Distribution of CD4+CXCR5+ cells among patients with IgG4-RD. (A) Merged image of IgG4-RD lacrimal gland stained for CD4 and CXCR5. (B) IgG4-RD lacrimal gland with DAPI counterstain. (C) Merged image of IgG4-RD lymph node stained for CD4 and CXCR5. (D) IgG4-RD lymph node with DAPI counterstain. (E) Merged image of IgG4-RD pancreas stained for CD4 and CXCR5. (F) IgG4-RD pancreas with DAPI counterstain. Scale bars, 50 µm; magnification, ×200. IgG4-RD, immunoglobulin G4-related disease; CD4, cluster of differentiation 4; CXCR5, C-X-C chemokine receptor type 5.

Fig 3: Expression of IL-21 in involved tissues of patients with IgG4-RD. (A) Representative micrographs stained for IL-21 of pancreas (left), orbital soft tissue (middle), and lymph node (right) with IgG4-RD (scale bar, 100 µm; magnification, ×100). (B) Representative micrographs were from the orbital soft tissue in IgG4-ROD patients. Immunofluorescent double staining of IL-21-positive cells (red) and CXCR5+ cells (green), cells in yellow indicate the coexpression of IL-21 and CXCR5 (scale bars, 50 µm; magnification, ×200). (C) Total IHC scores for IL-21 for patients with IgG4-RD. *P<0.05. (D) Correlation between IgG4 production and IL-21 IHC scores in orbital specimens from IgG4-ROD as determined by Spearman's rank test. IgG4-RD, immunoglobulin G4-related disease; IgG4-ROD, immunoglobulin G4-related ophthalmic disease; type 1 AIP, type 1 autoimmune pancreatitis; IgG4-RL, immunoglobulin G4-related lymphadenopathy; CXCR5, C-X-C chemokine receptor type 5; IL-21, interleukin 2; IHC, immunohistochemistry.

Fig 4: Frequency of CD4+CXCR5+ Tfh cells among patients with IgG4-RD. *P<0.05. IgG4-RD, immunoglobulin G4-related disease; IgG4-ROD, immunoglobulin G4-related ophthalmic disease; type 1 AIP, type 1 autoimmune pancreatitis; IgG4-RL, immunoglobulin G4-related lymphadenopathy.

Fig 5: CXCR5 mediates the VCAM‐1 expression and cell migration in response to CXCL13 incubation. A, The CL1‐0 lung cancer cells were transfected with CXCR5 siRNA for 24 h, and the knockdown efficiency of CXCR5 was confirmed by Western blot. B and C, The CL1‐0 lung cancer cells transfected with CXCR5 siRNA were further performed with cell migration assay B, in the presence of CXCL13 (30 ng/mL) for 24 h, as well as qPCR C, to detect VCAM‐1 expression. D and E, The CL1‐0 lung cancer cells were pre‐incubated with CXCR5 neutralized antibody (0.5 and 1 μg/mL) for 1 h and then performed with cell migration assay D, and qPCR E, in the presence of CXCL13 (30 ng/mL) for 24 h to evaluate cell migratory ability and VCAM‐1 expression, respectively. Results are expressed as the mean ± SD of triplicate samples. *P < .05 compared to the control group. #P < .05 compared to the CXCL13‐treated group