Immunological aspects of intravesical administration of Bacillus Calmette-Guérin (BCG) in the guinea pig.

The only form of effective immunotherapy for human cancer is the intravesical administration of BCG in the treatment of superficial bladder tumors. In this study BCG was administered intravesically (once a week for six consecutive weeks) in guinea pigs to investigate the immune response. Both specific immune responses against BCG itself and nonspecific immune responses such as leukocyte subset distribution, mitogenic (ConA, PHA, LPS) lymphocyte stimulation and spontaneous cytotoxic (NK and LAK cell) activity were determined in the regional draining (iliac) lymph node and in the spleen. The PPD skin test became positive after the fourth intravesical instillation of BCG when 1 X 10(5) culturable particles or higher dosages of BCG were administered. A low dose of 1 X 10(3) c.p. of BCG induced a positive PPD skin reaction in 2 of 4 animals after six BCG instillations. After six BCG instillation BCG immune lymphocytes were present both in the iliac lymph nodes and in the spleen. No differences in mitogenic responses to ConA, PHA and LPS were observed in iliac lymph nodes or the spleen between placebo or BCG treated animals. In the regional iliac lymph nodes a significantly increased number of leukocytes was present. These lymph node cells showed a significant increase in the expression of MHC class II (Ia) immune response antigen on their surface. In the spleen no differences were observed after BCG administration regarding the number of cells present and in terms of the Ia antigen expression of the leukocytes.(ABSTRACT TRUNCATED AT 250 WORDS)