Email updates

Keep up to date with the latest news and content from Arthritis Research & Therapy and BioMed Central.

This article is part of the supplement: 25th European Workshop for Rheumatology Research

Poster presentation

Infliximab treatment does not induce apoptosis in peripheral blood mononuclear cells up to 24 hours after initiation of treatment in rheumatoid arthritis patients

CA Wijbrandts, P Reinders-Blankert, P Klarenbeek, TJM Smeets, MJ Vervoordeldonk and PP Tak

Author Affiliations

Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, The Netherlands

For all author emails, please log on.

Arthritis Research & Therapy 2005, 7(Suppl 1):P114  doi:10.1186/ar1635

The electronic version of this article is the complete one and can be found online at:


Received:11 January 2005
Published:17 February 2005

© 2005 BioMed Central Ltd

Background

Apoptosis of peripheral blood T lymphocytes from patients with Crohn's disease has been described after in vitro activation followed by incubation with infliximab. These ex vivo data raised the question of whether in vivo treatment of rheumatoid arthritis (RA) with the chimeric tumor necrosis factor alpha antibody, infliximab, causes apoptosis in peripheral blood mononuclear cells. This study was designed to detect the early effects of infliximab treatment on apoptosis in the peripheral blood of patients with RA.

Methods

Ten patients with active RA (Disease Activity Score [DAS 28] > 3.2) received 3 mg/kg infliximab intravenously in combination with methotrexate (mean dose of 25 mg weekly). All 10 patients underwent blood sampling before, 1 hour after and 24 hours after the administration of infliximab. Apoptosis was determined using double staining with annexin-V, as an early marker of apoptosis, and 7-amino-actinomycin D (AAD) to exclude necrotic cells from this population. Peripheral blood erythrocytes were lysed and the mononuclear cells were incubated with the different antibodies. The percentages of annexin-V-positive and 7-AAD-negative monocytes and lymphocytes were analyzed by flow cytometry. For statistical analysis, a paired t test was used to compare the percentages of apoptotic cells 1 hour and 24 hours after treatment with those at baseline.

Results

All samples were analyzed for the presence of and change in apoptosis. At baseline, the median percentage of apoptotic monocytes was 0.90% (range 6.23–0.19); 1 hour after treatment, the median percentage was 0.56% (range 2.90–0.32) and 24 hours after treatment the median percentage was 0.21% (range 2.90–0.00). In the lymphocyte population, the median percentage of apoptotic cells was 0.98% (range 2.15–0.00) at baseline as compared with 0.52% (range 6.30–0.00) 1 hour after treatment and 0.39% (range 2.85–0.00) 24 hours after infliximab administration.

Conclusion

In this in vivo study we found no statistically significant increase from baseline in the percentage of apoptotic monocytes or lymphocytes in the peripheral blood of RA patients at 1 hour or 24 hours after infliximab treatment.

Acknowledgement

Supported by Centocor.