Rituximab vs Infliximab: Immune and Clinical Impact in Rheumatoid Arthritis

Abstract

Rheumatoid arthritis is a chronic systemic autoimmune disease in which inadequate control of inflammatory activity leads to progressive joint destruction and disability. The aim of this study was to compare the immunological effects and clinical efficacy of rituximab and infliximab in patients with rheumatoid arthritis who had not achieved an adequate response to prior therapy with disease-modifying antirheumatic drugs (DMARDs). The study included patients with a confirmed diagnosis who were prescribed one of the two biological agents. Changes in clinical and laboratory markers of disease activity—including the number of tender and swollen joints, levels of acute-phase reactants and immunoglobulins, and peripheral blood lymphocyte immunophenotyping—were assessed at baseline and during follow-up. Adverse events were recorded, and treatment persistence was analyzed. Both drugs were found to provide a similar reduction in clinical disease activity by the end of the follow-up period. However, their immunological effects differed fundamentally: rituximab induced a profound and sustained reduction in the number of CD20-positive B lymphocytes, whereas infliximab had no direct effect on the B-cell pool. Antibodies against the drug were detected in a subset of patients treated with infliximab; their presence was associated with reduced drug concentration and a diminished clinical response. No such pattern was observed in the rituximab group. These findings indicate that the choice of a biological agent for rheumatoid arthritis should be based not only on expected clinical efficacy but also on the patient's individual immunological characteristics.