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

Poster presentation

Abatacept (CTLA4-Ig) modulates human T-cell proliferation and cytokine production but does not affect lipopolysaccharide-induced tumor necrosis factor alpha production by monocytes

PM Davis, SG Nadler, KA Rouleau and SJ Suchard

Author Affiliations

Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey, USA

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Arthritis Research & Therapy 2005, 7(Suppl 1):P21  doi:10.1186/ar1542


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 and objectives

Activated T cells play a central role in the inflammatory cascade leading to the joint inflammation and destruction characteristic of rheumatoid arthritis (RA). The cytokines secreted by activated T cells are thought to both initiate and propagate the immunologically driven inflammation associated with RA.

Abatacept, the first of a new class of agents for the treatment of RA that selectively modulates the co-stimulatory signal required for full T-cell activation, was evaluated for its ability to regulate human T-cell proliferation and cytokine production in vitro. The effect of abatacept on lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) from monocytes was evaluated to distinguish the impact of this agent on innate versus adaptive, antigen-specific immune responses.

Methods

T cells were isolated from normal healthy human volunteers. The effect of abatacept on antigen-dependent T-cell activation was evaluated using either an irradiated human B-cell line (PM-LCL) as the antigen-presenting cells (APCs) for a primary mixed lymphocyte reaction (MLR), or autologous E-PBMCs as APCs for a recall response to tetanus toxin (TT). Cytokines were measured at various times post activation, with proliferation determined on day 5. Monocytes were isolated by elutriation, challenged with LPS and TNF-α levels measured at 6 hours. Chi L6 was included as a non-specific fusion protein control.

Results

Abatacept significantly downmodulated T-cell proliferation, in both primary and recall responses, at concentrations between 0.3 and 100 μg/ml, with maximal inhibition (~60–80%) observed at ~3–10 μg/ml. These concentrations are below the abatacept trough plasma levels observed in patients receiving a clinically effective dose [1]. Under conditions of maximal inhibition of proliferation, and similar to trough plasma levels in patients (30 μg/ml), abatacept also inhibited IL-2, TNF-α and interferon gamma secretion in both primary and TT-dependent recall responses. However, the extent, kinetics and rank order of cytokine inhibition by abatacept was somewhat different between primary and recall responses. In contrast, abatacept did not inhibit LPS-induced TNF-α production in primary human monocytes, demonstrating that its action is restricted to antigen-dependent T-cell responses.

Conclusion

Abatacept, a selective co-stimulation modulator, significantly inhibited the activation (as measured by cytokine production) and proliferation of human T cells in the context of a primary MLR or TT-dependent memory response. This inhibition occurred at concentrations below the serum Cmin levels observed in patients receiving a clinically effective dose of abatacept [1] (10 mg/kg monthly), consistent with suppression of T-cell activation in vivo. There was no effect of abatacept on LPS-stimulated TNF-α production in monocytes indicating that this agent may largely preserve innate immune responses.

References

  1. Kremer JM, Westhovens R, Leon M, Di Giorgio E, Alten R, Steinfeld S, Russell A, Dougados M, Emery P, Nuamah IF, et al.: Treatment of rheumatoid arthritis by selective inhibition of T-cell activation with fusion protein CTLA4Ig.

    N Engl J Med 2003, 349:1907-1915. PubMed Abstract | Publisher Full Text OpenURL