Clinical and serological associations of anti-Ku antibody

Objective. To ascertain the clinical and serological associations of anti-K u antibody. Methods. Twenty-seven patients over a 7 year period (1987-1996) had anti-Ku antibody detected by counterimmunoelectrophoresis (CIEP). Nineteen patient s were available for clinical review. Five patients were assessed by chart review. Serum was taken at review for repeat antibody analysis. Patients we re assigned to diagnostic groups based on the American College of Rheumatol ogy criteria. Results. There were 22 women and 5 men. The duration of symptoms ranged fro m one year to 28 years, Nine patients fulfilled criteria for systemic lupus erythematosus (SLE), 4 scleroderma, 3 rheumatoid arthritis (RA), one disco id lupus, and 7 had an undifferentiated connective tissue disease. There wa s a low incidence of renal (2/24) and central nervous system involvement (1 /24); 19/24 had Raynaud's phenomenon, 15/24 had inflammatory arthritis but only one had erosions on radiograph; 11/24 reported esophageal reflux sympt oms. Three of 24 patients had myositis. All patients had anti-nuclear antib ody using indirect immunofluorescence of > 640 titer with a speckled and nu cleolar pattern. Anti-Ku antibody was detected on CIEP in 15/19 sera availa ble for repeat testing. Three patients had anti-Re antibody, 2 had anti-U1R NP antibody, one patient had anti-topoisomerase-1 and anti-lie. Conclusion. Anti-Ku antibody is found in a wide variety of connective tissu e syndromes. While several patients fulfilled diagnostic criteria for SLE, scleroderma, and RA, their clinical features were usually mild and did not form a distinctive clinical pattern. Common features associated with anti-g u were Raynaud's phenomenon, arthralgia, skin thickening, and esophageal re flux. Few patients had associated autoantibody specificities found in SLE o r scleroderma.