Pentoxifylline, a phosphodiesterase inhibitor, induces immune deviation in patients with multiple sclerosis

Abstract

The outcome of immune responses can be predicted by the lymphokine production pattern of the participating cells. Cytokines of the T helper type 1 (Th1) cells mediate inflammatory responses and delayed-type hypersensitivity (DTH), whereas Th2-like T cells predominantly produce cytokines, which stimulate antibody production by B cells. Immunoregulatory therapy of autoimmune diseases with unknown antigens may be achieved by inhibiting the production of inflammatory cytokines and induction of protective cytokines of Th2-like T cells. To determine the immunoregulatory capacity of the phosphodiesterase inhibitor pentoxifylline (PTX), which is known to suppress the production of tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), this drug was used in mitogen and antigen-stimulated lymphocyte cultures as well as in patients with multiple sclerosis. PTX significantly decreased TNF-α and interleukin-12 (IL-12), whereas it increased IL-4 and IL-10 production. In addition, PTX inhibited cell proliferation, which was associated with a marked reduction in CD25 (IL-2 receptor α-chain) and CDS4 (intercellular adhesion molecule-1; ICAM-1) expression. Increasing doses of PTX significantly reduced TNF-α and IL-12 mRNA expression of blood mononuclear cells, but increased IL-4 and IL-10 expression in eight patients with relapsing-remitting multiple sclerosis. These results indicate that PTX modulates immune reactions favouring a Th2-like response and may therefore be useful for the treatment of autoimmune diseases with a dominant Th1-like T cell response.