Diagnosis:
Autoimmune ANA testing
• Antinuclear antibody (ANA) testing provides a screening test for connective tissue diseases, including SLE, drug-induced lupus-like syndrome, mixed connective tissue disease, Sjögren syndrome, scleroderma, CREST syndrome, polymyositis-dermatomyositis, and rheumatoid arthritis. The figure shows a centromeric staining pattern.
• The standard method for ANA testing in the United States uses IFE analysis of HEp-2 cells. Mouse liver cells can also be used, but they are less sensitive than Hep-2 cells. Nondiseased individuals may exhibit ANA titers as high as 1:80 when HEp-2 cells are used.
• Enzyme-linked immunosorbent assay (ELISA) based methods can be used for screening purposes. However, the disadvantage of using such an approach is that this methodology cannot provide information on IF patterns, which have been the gold standard for decades.
• There are three antibodies commonly associated with systemic scleroderma: (1) anti-topoisomerase I, (2) anti-RNA polymerase, and (3) anti-centromere. Thus, a speckled or nucleolar pattern may be observed.
• Anti-centromeric antibodies are common (44% to 98%) in patients with CREST syndrome (a subset of scleroderma patients). CREST patients suffer from skin changes that are not systemic but are limited to the hands and face.
