The relationship of salivary gland function to elevated serum IgG4 in autoimmune pancreatitis

To compare salivary gland function in autoimmune pancreatitis (AIP) patients with and without an elevated serum IgG4 concentration.

We allocated 14 AIP patients into 2 groups: one group had high (>135 mg/dL) serum IgG4 and the other low serum IgG4. Sialochemistry and submandibular and parotid gland scintigraphy were done in these patients.

Serum IgG4 levels were elevated in 10 patients. Bilateral submandibular gland swelling was present in 5 patients with a high serum IgG4; there was no swelling in patients with a low serum IgG4. The salivary Na+ concentration was increased significantly in both patient groups (p<0.01) compared to controls. The beta2-microglobulin concentration was significantly higher in patients with a high serum IgG4 than in those with a low serum IgG4 (p<0.05) and controls (p<0.01). On submandibular and parotid gland scintigraphy, both the ratio of the cumulative peak count to the injected radionuclide (PCR) and the washout ratio (WR) were significantly lower in the high serum IgG4 group than in controls (p<0.01). In the low serum IgG4 group, the PCR on submandibular gland scintigraphy, and the PCR and WR on parotid gland scintigraphy were significantly lower than in controls (p<0.05, p<0.01 and p<0.05, respectively). On submandibular gland scintigraphy, the PCR was significantly lower in the high serum IgG4 group than in the low serum IgG4 group (p<0.05).

Salivary gland function was impaired in all AIP patients, but it was more impaired in patients with a high serum IgG4 than in those with a low serum IgG4.