A methylxanthine derivative with hemorrheologic and immunomodulating properties. Pentoxifylline inhibits phosphodiesterase, resulting in increased levels of cyclic adenosine monophosphate (cAMP) in erythrocytes, endothelium, and the surrounding tissues. This leads to vasodilation, improves erythrocyte flexibility, and enhances blood flow. In addition, the increased level of cAMP in platelets inhibits platelet aggregation, which may contribute to a reduction in blood viscosity. This agent also inhibits production of tumor necrosis factor-alpha and interferon-gamma, while it induces Th2-like (T-helper 2) cytokine production, thereby inhibiting Th1-mediated (T-helper 1) inflammatory and autoimmune responses.