Immune complex specific for the pancreatic duct antigen in patients with idiopathic chronic pancreatitis and Sjögren syndrome.

Circulating immune complexes (ICs) containing the pancreatic antigen against SP3-1 monoclonal antibody were measured in patients with idiopathic chronic pancreatitis (ICP) and Sjögren syndrome (SjS) by Raji cell and solid-phase radioimmuno-assays (RIA). The mean serum levels of ICs measured by solid-phase RIA were significantly higher in patients with ICP (n = 23) and SjS (n = 21) than control (n = 15, p < 0.05, p < 0.02, respectively). ICs were positive in 10 patients with ICP (43%) and 12 SjS patients (57%). Raji cell assay also revealed a significantly higher serum ICs levels in patients with ICP (n = 17) and SjS (n = 12) compared with those of control (n = 7, p < 0.025, p < 0.005, respectively). Seven patients with ICP (41%) and 8 SjS patients (67%) had positive ICs. This was in contrast to the normal level of ICs in patients with alcoholic chronic pancreatitis, primary biliary cirrhosis, and chronic thyroiditis. Our analysis demonstrated a significant and positive relationship between RIA and Raji cell assay (r = 0.70, p < 0.05). Our results suggest that ICs specific for SP3-1 may play a role in the pathophysiology of ICP and SjS.