Epidermal cell surface-associated IgG in patients with primary Sjögren's syndrome: in vitro evidence for immune complex binding

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.