Calreticulin - an autoantigen in autoimmune and tumor diseases

Calreticulin - an autoantigen in autoimmune and tumor diseases Introduction: Calreticulin, a calcium binding protein and chaperon, is a common autoantigen in autoimmune diseases. Antibodies (Ab) against calreticulin (CRT) were recently detected in sera of some patients with hepatocellular carcinoma (CaH) and pancreatic tumors (CaP) using a combination of two-dimensional electrophoresis and Western blotting. Aims: The aims of this study were a) to quantify the levels of IgA and IgG Ab against CRT in sera of patients with CaH, CaP (metastatic, non metastatic), colorectal carcinoma, pancreatitis and viral hepatitis. b) to analyse the antigenic epitopes of CRT, c) to prepare the first half of human recombinant CRT. Methods: Direct ELISA test with human recombinant CRT as antigen was used for testing the levels of serum Ab. Antigenic epitopes of CRT recognised by serum IgA and IgG Ab were analysed by PEPSCAN method in patients with CaH and CaP. The first half of human recombinant CRT was prepared by recombinant technology and subsequently purified by affinity chromatography. Results: We found significantly elevated levels of IgA anti-CRT Ab in sera of patients with CaH (P< 0,01, 8/13), CaP (P< 0,05, 17/38), CaP with liver metastasis (P< 0,01, 2/8) and pancreatitis (P< 0,05, 4/14) in contrast to healthy controls..