MULTIPLE NUCLEAR DOT ANTINUCLEAR ANTIBODY IN PATIENTS WITHOUT PRIMARYBILIARY-CIRRHOSIS

Multiple nuclear dot (MND), or pseudocentromere, anti-nuclear antibody (ANA) is an uncommon pattern associated primarily with primary biliar y cirrhosis (PBC) and anti-mitochondrial antibody (AMA). A 53 kDa anti gen with an apparent molecular mass of 100 kDa as found on sodium dode cyl sulphate-polyacrylamide gel electrophoresis is thought to be respo nsible for the uncommon pattern. This study analyzes sera from 21 pati ents without PBC or AMA that produced the uncommon MND ANA immunofluor escence pattern. Diseases present include lupus, rheumatoid arthritis and scleroderma. On immunoblotting nineteen of 21 (91%) bound a 70 kDa protein. Western blot analysis showed that this nuclear antigen was d ifferent from pyruvate dehydrogenase, p80 coilin and the antigen respo nsible for MND ANA in those with PBC. Affinity purified anti-70 kDa re produced the MND ANA immunofluorescence pattern. Thus, the MND ANA in patients without PBC/AMA is associated with binding to a 70 kDa nuclea r protein and not with a 53 kDa antigen (that runs at 100 kDa) found i n those with MND and PBC/AMA. The data demonstrate that MND antigen wi thout PBC/AMA is immunologically distinct from the pattern when found with PBC/AMA.