COMPARISON OF 4 IMMUNOBLOT SYSTEMS FOR TH E DIFFERENTIATION OF ANTIBODIES AGAINST NUCLEAR AND CYTOPLASMIC ANTIGENS

Since recently, immunoblots for detection and differentiation of antib odies against nuclear antigens (ENA), other nuclear antigens and cytop lasmic antigens, blotted on nitrocellulose strips (Western blot techni que) became commercially available. The aim of our analysis was to com pare the specifity and sensitivity of four different immunblot systems (blots A, B, L, V). We examined 20 sera of patients with various clin ically confirmed connective tissue diseases. The sera contained a tota l of 32 different antigens. The antibodies in the sera were defined by double immunodiffusion (Ouchterlony) test, immunofluorescence (HEp2 c ells) and by comparison with WHO reference sera. Results: Blot a detec ted 81%, blot B 30 %, blot L 57 % and blot V 58 % of the auto-antibodi es in the tested sera. In addition, we analysed the number of false po sitive bands. Blot A detected one, blot B 15, blot L none and blot V 1 0 false positive auto-antibodies. As sensitivity and specifity differ between the various blot systems, each clinical laboratory should firs t test the commercially available blot systems under daily conditions with standard sera. In comparison of four different blot systems, blot A was superior to the others with regard to sensitivity, specificity, quality and laboratory handling.