Biology of the Antibody Specificity

From the Department of Dermatology, University of Cincinnati College of Medicine. Reprint requests: Diya F. Mutasim, MD, Professor and Chairman, Department of Dermatology, University of Cincinnati, PO Box 670592, Cincinnati, OH 45267-0592. E-mail: mutasdf@email. uc.edu. Copyright © 2000 by the American Academy of Dermatology, Inc. 0190-9622/2000/$12.00 + 0 16/2/103582 C onnective tissue diseases (CTDs) are a group of autoimmune disorders that have overlapping clinical features (Table I). The accurate diagnosis of a patient with one of these disorders depends on the evaluation of 4 parameters, namely clinical findings, histopathology, tissue immunofluorescence, and serologic testing. This article is limited to the serologic evaluation. Serologic testing does not substitute for evaluation of the other criteria. Serologic testing does help to confirm a clinical diagnosis and classify subsets of a CTD and thus help predict prognosis. For example, a patient who presents with cutaneous lupus erythematosus and who is found to have significantly high antibody titer to native DNA (nDNA) (or double-stranded DNA [dsDNA]) likely has systemic lupus erythematosus (SLE) with cutaneous involvement.1-4 In addition, a patient who has cutaneous sclerosis, calcinosis, and esophageal dysmotility and who is found to have anticentromere antibodies is much more likely to have a benign course associated with the CREST syndrome (calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia)5,6 rather than the usually severe course associated with systemic sclerosis (SSc).