Autoantibodies in Patients with Rheumatoid Arthritis

Aim:  The aim of this study is to examine the diagnostic value of autoanitbodies in patients suffering from rheumatoid arthritis. We evaluated the presence of the following autoantibodies: rheumatoid factor (RF), antinuclear antibodies (ANAs), antibodies against cadiolipin (a-CL) and antibodies against cyclic citrullinated peptide (anti-CCP).
Methods:  We studied the presence of RF, ANA, a-CL and anti-CCP in 40 patients with rheumatoid arthritis. Rheumatoid factor was measured using nephelometric method, while ANAs were examined by indirect immunofluorescence technique using Hep-2 cells as substrate. Sera that reacted at 1/80 dilution were classified as ANA positive. Positive sera were studied up to 1/1280 dilution. A-CL and anti-CCP were measured by enzyme-linked immunosorbent assay.
Results:  RF was positive in 30 patients (75%), ANA in 15 (37%), a-CL in 10 (25%) and anti-CCP in 36 (90%). Predominant pattern of nuclear staining of ANA-positive sera was homogenous and speckled type. ANA titres were particularly low; most patients (6) had ANA titre equal to 1/80, and five patients had a titre of 1/160, while only four out of 40 had an ANA titre of 1/320.
Conclusions:  Autoimmune disorders such as RA are characterized by various autoantibodies that usually are not specific, as they are present in many other diseases. However, RF and especially anti-CCP are very often and show higher specificity for RA, being useful diagnostic serological markers. On the other hand, ANA and a-CL are less common in RA paitents; they may be useful in terms of prognosis and treatment, but they always should be evaluated in correlation with the clinical features and the rest of the laboratory findings of each patient.