Immunomodulating activity of heparin.

Aside from its well-known anticoagulant action, heparin has many other biologic effects. Recent data emphasize the immunomodulatory effects of low dose heparin. The agent alters the traffic of lymphocytes blocking their expression of heparanase, an enzyme that digests the extracellular matrix allowing cell penetration to target tissues. It also has a weak direct immunosuppressive action in vitro and in vivo. Oral administration of heparin may cause immunosuppression, although the effects are weaker than after subcutaneous administration.