Nonspecific immunomodulating effects of BCG vaccine on antibody-dependent cell-mediated cytotoxicity.

The effects of BCG vaccine on antibody-dependent cell mediated cytotoxic (ADCC) activity of spleen lymphocytes were examined after BCG treatment. A modified plaque assay method, using sheep red blood cells (SRBC) as targets and IgG antibodies from rabbit anti-SRBC serum, was applied. The changes of ADCC activity were different in spleen lymphocytes according to the route and the timing of the administration of the vaccine. Following i.p. administration we observed an immunosuppressive effect in mouse and rat spleen effector cells within the first seven days. The ADCC activity level returned to normal by the 14th day. The cytolytic activity was maximal at the 21st day after treatment, and decreased slowly thereafter. The ADCC activity of mouse spleen lymphocytes did not change within the first seven days after i.v. BCG administration while the maximal cytolytic activity was induced on the 14th day but it was lower than the peak value found after i.p. treatment.