Systemic autoimmune rheumatic diseases in 2013: Problems of laboratory diagnosis

Progress in the laboratory diagnosis of systemic autoimmune rheumatic diseases (SRAD) is caused by the ever increasing clinical introduction of new highly productive methods for immune analysis using computer-aided systems and multiplex proteomic technologies. The urgent problem in the laboratory diagnosis of SRAD is the standardization of current methods for the detection of autoantibodies (autoAb), including the preparation of international reference materials for the calibration and external quality assessment of immunological assay. New autoAb technologies have a higher analytical validity than the previously used classical techniques immunodiffusion, agglutination, and immunofluorescence; however, their diagnostic sensitivity and specificity for SRAD have been poorly studied. Particular emphasis is laid on the standardization of the methods for examining antinuclear antibodies (ANAb), the major serologic marker of SRAD. According to the EULAR/ACR guidelines, indirect immunofluorescence reaction (IIFR) using human HEp-2 cells as substrate is the gold standard and a primary screening ANAb method. New methods for solid-phase analysis (enzyme immunoassay, multiplex test systems, etc.) cannot substitute the primary screening of ANAb using IIFR-HEp-2 as they identify antibodies to the limited number of antigens, increasing the number of false- negative results. The computer-aided systems for interpreting cell fluorescence tests contribute to the standardization and enhancement of the efficiency of detection of ANAb and other autoAb by IIFR. The use of complex diagnostic indices based on the multiparametric analysis of laboratory biomarkers in the serum makes it possible to most fully and objectively assess complex molecular mechanisms for the pathogenesis of SRAD, thus radically improving the early diagnosis, the estimation of the activity and severity of disease, the prediction of the outcomes of a pathological process and the response to treatment.