Stimulation of tetanus toxoid-specific immune responses by a traditional Chinese herbal medicine.

The immunomodulatory properties of botanical medicinals are well-documented. In this study, the capacity for the traditional Chinese herbal medicine, Rehmannia Six Formula (R6F), to stimulate anti-tetanus toxoid (TT) immunity following oral administration to mice was examined. A significant rise in serum anti-TT antibody levels were observed in R6F-treated mice immunized with a minimum immunogenic dose of 10 microg TT suggesting an oral adjuvant effect. No such enhancement was found for unimmunized mice treated with R6F. This anti-TT response was preferentially IgG and antigen-specific in relation to antibody reactivity to a panel of unrelated antigens. The R6F used was safe with no adverse effects on mouse weight or survival, providing evidence for the use of R6F as an oral adjuvant.