Figure 1

Immunohistochemical staining of activation-induced cytidine deaminase (AID). (a) IgG4-related sialadenitis (×100), (b) IgG4-related sialadenitis (×400). Greater numbers of strongly AID-positive cells were noted in IgG4-related sialadenitis than in those from healthy controls or patients with sialolithiasis. Ductal epithelia in IgG4-related sialadenitis were also positive for AID. In addition to AID-positivity in the germinal centres of AID-positive cells, the interfollicular areas were also AID-positive. AID-positive interfollicular areas were observed in lymphoid cells, plasma cells, and plasmacytoid cells. (c) Sialolithiasis (×400). Although lymphoid cell infiltration was observed in patients with sialolithiasis, fewer AID-positive cells were observed compared with IgG4-related sialadenitis. (d) Normal submandibular gland (×400). No AID-positive cells were noted in normal tissue.