Interspecies crossreactive antigen of the pancreatic duct cell prepared by monoclonal antibody. A preliminary study of its immunological significance in patients with chronic pancreatitis associated with Sjögren's syndrome.

An interspecies cross-reactive antigen (mol wt 60,000) for pancreatic duct cells was prepared by a monoclonal antibody (SP3-1; IgM). Homogenized pig pancreatic tissues were separated by gel filtration chromatography with Sephadex G-100 and ion-exchange column chromatography with DEAE-Sephacel and used as immunogens. Immunohistochemically, antigens against SP3-1 were distributed in duct cells of the pancreas, salivary gland, lacrimal gland, esophageal gland, bile duct, and the distal renal tubule in the pig, monkey, and human. The antigenic determinant contained protein, but not sialic acid or monosaccharide. Preliminary leukocyte migration inhibition test (n = 5) showed positive in four patients with definite Sjögren's syndrome (SS), whereas one patient without autoantibodies similar to SS showed negative. These findings suggest that this antigen may be involved in the pathophysiology in these conditions.