Serum A1 and B apolipoprotein determination: comparison of an immunoturbidimetric method with a monoclonal-antibody-based radial immunodiffusion assay.

Epidemiological and clinical evidence have indicated that apolipoprotein A1 and B determination can better define the lipoprotein pattern in normal subjects and in subjects with coronary heart disease. In this paper, a recent immunoturbidimetric method for routine apolipoprotein A1 and B measurement (using the Turbitimer system and commercially available antisera) has been evaluated. The precision and the accuracy of the method have been previously considered. Within-run and between-run coefficients of variation (ranging from 1.67% to 5.04%) for both assays indicate good precision of the method. Accuracy was evaluated on 2 consecutive days (n = 10 each run) using a standard serum for apolipoprotein A1 and B. The bias obtained was 3.79% for apolipoprotein A1 and 2.30% for B. Apolipoproteins A1 and B were then measured in 100 normal and hyperlipemic sera with the immunoturbidimetric assay and radial immunodiffusion (using the monoclonal antibodies). The data obtained were evaluated by linear regression analysis (Al, r = 0.893; B, r = 0.862). The good correlation between the two methods suggests that the immunoturbidimetric assay can be usefully performed for routine apolipoprotein A1 and B determination because of its lower cost, rapidity, and simplicity.

[The lupus band test in the diagnosis of systemic lupus erythematosus: its decisive usefulness in cases negative for anti-ds-DNA and anti-SM]. / Il lupus band test nella diagnosi del lupus eritematoso sistemico: sua decisiva utilità nei casi anti ds-DNA ed anti-Sm negativi.

The aim of this study was to evaluate an immunofluorescence skin test, the lupus band test (LBT), in comparison to other criteria as classified by the American Rheumatic Association for the diagnosis of systemic lupus erythematosus (SLE). Twenty patients with SLE and another 24 with different connective tissue diseases (rheumatoid arthritis 16, dermatomyositis 3, necrotizing vasculitis 5) were studied. Antinuclear antibodies (ANA) appeared very sensitive (100%) in the diagnosis of LES, though with a low specificity (63%). LBT was however both sensitive (80%) and specific (100%). Others ARA laboratory criteria (anti-dsDNA, anti-Sm, VDRL and hematological disorders) were also less sensitive and/or less specific than LBT. Most interestingly, LBT was positive in 7 SLE cases in which both dsDNA and Sm antibodies were negative. Thus, LBT appears a useful test in the diagnosis of SLE. In addition, it may be of critical value in certain subsets of patients in which the present ARA criteria may not suffice for diagnosis.