Background: Infliximab, an antitumour necrosis factor-alpha chimeric monoclonal antibody, is effective for the treatment of severe psoriasis. While the induction of antinuclear antibodies (ANA) and antidouble-stranded-DNA antibodies (anti-dsDNA-ab) is frequently observed in patients with rheumatoid arthritis and Crohn disease receiving infliximab, the incidence of induced biological and clinical autoimmunity remains unknown in the context of psoriasis.
Objectives: To investigate biological and clinical signs of autoimmunity in 28 patients receiving infliximab for severe, recalcitrant forms of psoriasis, and the clinical response to treatment.
Methods: Twenty-eight patients, 15 men and 13 women (median age 39.4 years) with psoriasis refractory to three or more systemic treatments were included. Twenty presented with plaque-type psoriasis [median Psoriasis Area and Severity Index (PASI) score 25.9; range 7.2-48], five with psoriatic erythroderma (median PASI score 54; range 48-72) and three with generalized pustular psoriasis (GPP). Psoriatic arthritis was present in 13 patients (46.4%). Infliximab 5 mg kg(-1) was given at week (W) 0, W2, W6 and every 8 weeks thereafter. Clinical data were assessed at baseline and before each infusion. Detection of ANA and of IgM and IgG anti-dsDNA-ab were performed at baseline and at W22 by immunofluorescence and enzyme-linked immunosorbent assay, respectively.
Results: The mean number of infliximab infusions was 5.5 (range 2-15). Among patients with plaque-type and erythrodermic psoriasis, 17 of 25 (68%) and three of five reached a PASI improvement of 75% or more, respectively, while rapid improvement of clinical and biological signs was observed in all three patients with GPP. The prevalence of positive detection of ANA raised from 12% at baseline to 72% at W22 (P = 0.0001), an increase which was also observed for IgM anti-dsDNA-ab (68% vs. 0%, P < 0.0001), while no significant change was observed for the IgG isotype (16% vs. 0%, P = 0.125). Three patients developed nonerosive polyarthritis, without any other criteria for systemic lupus.
Conclusions: The incidence of biological autoimmunity is high in patients with refractory psoriasis receiving infliximab. The concomitant onset of polyarthritis in three cases raises the need to investigate the incidence of autoimmune manifestations in psoriatic patients receiving infliximab in further large-scale studies.