Augmentation of the antibody response by lipoic acid in mice. II. Restoration of the antibody response in immunosuppressed mice.

Lipoic acid (Lip) was examined for its effect on the in vivo antibody response in mice. It was found that Lip significantly restored the suppressed antibody response to sheep erythrocytes (SRBC) in cyclophosphamide-injected mice when it was orally administered at 25 mg/kg twice a day for 4 consecutive days after immunization. On the other hand, Lip-administration did not affect the antibody response in normal mice immunized with SRBC. Normal or cyclophosphamide-treated mice were primed with horse erythrocytes (HRBC) and were given either saline or Lip for 3 consecutive days. HRBC-specific helper T cell activity of their spleen cells were compared by coculturing these cells with trinitrophenyl (TNP)-keyhole limpet hemocyanin-primed spleen cells in the presence of TNP-HRBC as the antigen. A significant restoration of the suppressed helper T cell activity was observed in the Lip-administered group. However, the helper T cell activity was not affected significantly by Lip-administration in normal mice. Lip could also partially restore the helper T cell activities that were suppressed by the treatment with hydrocortisone or X-ray irradiation.