cANCA exhibit a high sensitivity and specificity for Wegener's granulomatosis (prevalence 80 to 95%). The antibody titre correlates with the disease activity. Moreover, cANCA can occur in rare cases in microscopic arteritis and polyarteritis nodosa. The main target antigen of cANCA is proteinase 3. Autoantibodies against lactoferrin, myeloperoxidase, elastase and cathepsin G are associated with various autoimmune diseases like systemic lupus erythematodes, rheumatoid arthritis, Felty's syndrome, rapid progressive glomerulonephritis, microscopic polyarteritis, polyarteritis nodosa, Crohn's disease and ulcerative colitis. Autoantibodies against BPI were described in various diseases among them Wegener's granulomatosis, microscopic polyarteritis, colitis ulcerosa, Crohn's disease, vasculitis, autoimmune hepatitis. Antibodies against granulocytes (pANCA) are not only significant in the serological diagnosis of various forms of vasculitis, but also in the differential diagnosis of chronic inflammatory bowel disease. pANCA occurs in 67% of patients with ulcerative colitis and can also occur in Crohn's disease (7%).