Increased entry of CD4+ T cells into the Th1 cytokine effector pathway during T-cell division following stimulation in Behcet's disease

Abstract

Objectives. To investigate the relationship between the production of Th1/Th2 cytokines and cell kinetics, cell division and proliferation in patients with Behçet's disease (BD). Methods. Peripheral venous blood was drawn from patients with BD (n = 24; 10 patients with active and 14 patients with inactive BD) and normal subjects (n = 22). Peripheral blood mononuclear cells were separated immediately and were cultured with concanavalin A (Con A) followed by phorbol 12-myristate 13-acetate and ionomycin (PMA+Ion). Intracellular cytokine production of interferon-γ (IFN-γ) (Th1) and IL-4 (Th2) in CD4⁺ T cells was determined by flow cytometry. Furthermore, CD4⁺ T cells labelled with CFSE [5 (and 6) carboxyfluorescein diacretate, succinimidyl ester] were stimulated and the cells were analysed for entry into the cytokine production effector pathway during cell division in active BD and normal subjects. Results. In active BD, enhanced entry into the Th1 response effector pathway of CD4⁺ T cells was observed after stimulation with Con A followed by PMA+Ion. Analysis of CD4⁺ T cells at an identical cell division number in response to Con A followed by PMA+Ion revealed that IFN-γ-producing cells were increased in active BD patients compared with normal subjects. These results suggest that the Th1 response of dividing CD4⁺ T cells is predominantly operating in active BD. Dividing CD4⁺ T cells stimulated with Con A followed by PMA+Ion showed a phenotype of activated effector memory T cells (CD45RA^low, CD45RO⁺, CD69^high). Conclusions. Cell kinetics play a crucial role in Th1 cell differentiation and pathophysiology in BD.