To investigate the effect of cysteamine on mixed peripheral blood mononuclear cells (PBMCs)-chemically injured keratocytes reaction (mixed lymphocyte-keratocyte reaction; MLKR).

PBMC stimulation assay was performed after keratocytes were chemically injured with 0.05 N NaOH for 60 seconds. MLKR was treated with various concentrations of cysteamine (0-10 mM). Intracellular reactive oxygen species (ROS) formation was measured using the oxidation-sensitive fluorescent probe, 2'7'-dichlorofluorescein diacetate (DCF-DA). Proliferation rate of PBMCs stimulated by NaOH-treated keratocytes and secretion profiles of matrix metalloprotease-9 (MMP-9), transforming growth factor-beta1 (TGF-β1), interleukin-6 (IL-6), and macrophage migration inhibitory factor (MIF) were determined using the bromodeoxyuridine proliferation assay and enzyme-linked immunosorbent assay, respectively.

Proliferation rate of PMBCs was suppressed by cysteamine in a dose-dependent manner ( p = 0.019). Fluorescence of DCF-DA decreased depending on cysteamine concentration ( p < 0.001). MMP-9, IL-6 and TGF-β1 levels were suppressed by cysteamine in a dose-dependent manner ( p < 0.05), whereas MIF levels increased with cysteamine concentration of 0.5-10 mM ( p = 0.008).

These study results indicate that cysteamine induced the ROS-mediated inhibition of inflammatory cytokine release and proliferation of PBMCs stimulated by chemically injured keratocytes. Thus, cysteamine can be used in the treatment of chemical corneal burns.