CHARACTERIZATION OF TARGET ANTIGENS FROM ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN AUTOIMMUNE HEPATITIS TYPE-I

The occurrence of anti-neutrophil cytoplasmic antibodies (ANCA) has be en described in sera of patients with autoimmune hepatitis (AIH). The significance of this finding remains uncertain and the nature of the t arget antigen(s) has not yet been defined. We studied 32 sera from pat ients with AIH type-I and prepared extracts of human neutrophils to id entify the target antigen(s). A 43 kDa dominant immunoreactive protein was found and identified as the cytoskeletal component actin. Initial studies to define the antigenic determinants identified three differe nt actin domains.