Herbal factors in the treatment of autoimmunity-related habitual abortion

Deterioration in the balance of T helper-1 (Th1)/T helper-2 (Th2) during pregnancy may cause complications such as habitual abortion. Two types of immunity-related abortion are, at present, recognized. One is caused by autoimmune disorders as exemplified by the antiphospholipid antibody syndrome, in which the Th1/Th2 balance is excessively shifted to polarization of Th2. The other is caused by alloimmune fetal-maternal disorder, a condition associated with increased serum activity of Th1 cytokines. In Japan, herbal medicines such as Sairei-to (Sai) and Tokishakuyaku-san (Toki), which are prepared in granule forms and are manufactured, have been used in the treatment of these immunity-related habitual abortions and were reported to be clinically effective for these patients. The clinical effect of these herbal medicines can be explained by how they function in the maternal immune system. Sai and Toki enhance Th1 cytokine release from peripheral blood mononuclear cells (PBMCs) and might suppress the production of autoantibodies from B cells. However, Sai and Toki do not affect cytokine release from decidual mononuclear cells (DMCs), which are directly in contact with fetal trophoblasts. These herbal medicines might not enhance the killer activity of DMCs. Thus, the differential effects of Toki and Sai on the release of Th1/Th2 cytokines from PBMCs and DMCs may reveal the rationale for the use of these medicines in the treatment of autoimmunity-related habitual abortion.