Antinuclear antibodies (ANA) are a group of autoantibodies characterized by specificity for numerous antigenic determinants of cell nuclei. While the role of ANA’s in the pathogenesis of autoimmune disease is controversial, they are quite useful as disease markers, primarily for diagnostic screening and also to monitor the course of connective tissue diseases.
The MBL Bion ANA (Anti-Nuclear Antibody) TEST SYSTEM is an indirect fluorescent antibody assay utilizing HEp-2 tissue culture cells as a substrate for the qualitative and/or semi-quantitative determination of antinuclear antibodies in human serum. The MBL Bion ANA TEST SYSTEM is intended for use as an aid in the diagnosis of certain autoimmune diseases.
Because of the high correlation of positive antinuclear antibodies with SLE a negative ANA essentially rules out this disease. Although antibodies specific to DNA have a high correlation with SLE, antibodies to a number of other nuclear antigens appear to be of diagnostic and/or prognostic significance in diseases such as Progressive Systemic Sclerosis, Mixed Connective Tissue Disease, Sjogren's Syndrome, and Polymyositis, making ANA testing useful not only for SLE, but as a general screening tool for connective tissue diseases.
Among the methodologies available to detect ANA’s are EIA, ELISA, Dot Blot and the Indirect Fluorescent Antibody (IFA) technique. The antigen for the first three methods can either be a spectrum of clinically significant, specific autoantigens, a single mixture of autoantigens from a cell lysate, or a combination of the two. These methods are not as sensitive as IFA, nor can they detect the variety of autoantibodies. They also do not have the pattern recognition quality of the IFA. The IFA test is sensitive, screens for a wide variety of known and unknown autoantibodies and, through pattern recognition, offers insights into the probable identity of the antigen and associated autoimmune disorder. It is the dominant methodology in clinical laboratories at this time and the method of choice for ANA screening and semi-quantitation.
The antigen of the MBL Bion ANA substrate is a human epithelial cell (HEp-2) line established by Moore, Sabachensky and Toolan. HEp-2 cells have been shown to have greater sensitivity than tissue sections and yield sharper pattern recognition. The presence of mitotic figures aids in differential pattern recognition as well as detecting previously unreported nuclear antibodies. Antinuclear antibodies can be found in all major immunoglobulin classes (IgG, IgA or IgM), therefore, antihuman gammaglobulin conjugate that detects all classes is recommended for use in routine ANA testing.
Indirect fluorescent antibody assay utilizing HEp-2 tissue culture cells as a substrate for the qualitative and/or semi-quantitative determination of antinuclear antibodies in human serum.