What is the role of T cells and neutrophils in the pathogenesis of Behçet disease?

Updated: Dec 21, 2020
  • Author: Nicole Davey-Ranasinghe, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Systemic involvement of multiple organs is observed in Behçet disease, rooted primarily in the development of vasculitic or vasculopathic lesions in the affected areas. These areas may demonstrate microscopic evidence of inflammatory tissue infiltration with both T cells and neutrophils. [12, 6, 13, 14]

Studies of T lymphocytes have suggested a T-helper type 1 (TH1)–predominant response. Both CD4+ and CD8+ lymphocytes demonstrate higher concentrations in peripheral blood, with characteristic and corresponding elevations of cytokines (interleukin [IL]–2] and interferon-γ [IFN-γ]). Serum levels of IL-12 have also been shown to be elevated in patients with Behçet disease, possibly helping drive the response. Decreased levels and impaired activity of natural killer cells were demonstrated in bronchoalveolar lavage specimens of Behçet disease patients with pulmonary manifestations. [15]

Because of the degree of neutrophilic infiltration demonstrated in characteristic Behçet disease lesions (eg, hypopyon, pustular lesions, and pathergy reactions), the activity and function of these cells has been explored extensively. Unfortunately, existing studies offer inconsistent results regarding cell adhesion and chemotactic behavior, superoxide production, and phagocytic properties.

Thus, the specific role of neutrophils in Behçet disease has been difficult to characterize. Some studies have found that cytokine release in Behçet disease may, by an unknown mechanism, place neutrophils in a static pre-excitatory “primed” state, eventually triggered into hyperactivity by environmental stimuli at a lower threshold than in individuals who do not have Behçet disease. [16, 17, 18, 19]


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