Clinical immunology
Antinuclear antibodies and anti-cyclic citrullinated peptide antibodies in patients treated with adalimumab

Introduction: Adalimumab is a fully human monoclonal anti-TNF-α antibody used in the treatment of rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis. Other available TNF-α inhibitors, such as infliximab (chimeric monoclonal antibody) and etanercept (soluble anti-TNF-α receptor),
can induce the synthesis of autoantibodies and even cause drug-induced lupus. Anti-cyclic citrullinated (anti-CCP) antibodies are highly specific to rheumatoid arthritis and are predictive for rapid progression and erosive disease.

Objective: The aim of the study was to assess the presence of antinuclear antibodies (ANAs) and anti-CCP antibodies in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) before treatment with adalimumab and after 16 weeks of treatment.

Material and Methods: The study group consisted of 10 patients with RA, 7 patients with PsA, and 5 patients with AS. Autoantibodies were measured in their sera before the treatment and after 16 weeks. Antinuclear antibodies were tested by immunofluorescence. Anti-CCP antibodies were detected by
a commercial second-generation ELISA kit. The data analysis included clinical and laboratory response indices.

Results: Antinuclear antibodies were detected in 68% of the patients before treatment and in 54% after 16 weeks of therapy. Although the number of ANA-positive patients was reduced, there was no statistically significant change in their titers. Anti-CCP antibodies were detected in 41% (8 with RA, 1 with AS) of the patients before and in 36% after treatment (all patients with RA). Increases in anti-CCP antibody concentration were observed in 87.5% of the RA patients (P=0.069, Wilcoxon’s test). The mean increase was 77%.