Induction of apoptosis in human blood T cells by 7,8-dihydroneopterin: the difference between healthy controls and patients with systemic lupus erythematosus

Neopterin (Neo) and 7,8-dihydroneopterin (H2Neo) are produced by human monocyte-derived macrophages upon stimulation with IFN-γ. Increased amounts of Neo and H2Neo in human body fluids are found in many disorders, including viral infections and autoimmune diseases. Recent data suggest that neopterin derivatives may exhibit distinct biochemical functions activating redox-sensitive transcription factors and inducing apoptosis in various cell lines. In this study we investigated the effect of H2Neo on human peripheral blood T cells (PBT) from healthy blood donors in comparison with PBT isolated from patients with systemic lupus erythematosus (SLE). H2Neo induced apoptosis in healthy PBT in a concentration-dependent manner. In short time culture, a significantly lower ability of PBT isolated from patients with SLE to undergo apoptosis in response to H2Neo compared to healthy controls was detected. Our results suggest a possible role of the neopterin derivative H2Neo in T cell apoptosis mediated by stimulated monocytes/macrophages.