Immunotherapeutic response of concanavalin A-bound L1210 vaccine enhanced by a streptococcal immunopotentiator, OK-432.

Immunotherapeutic response to concanavalin A (Con A)-bound L1210 murine leukemic vaccine and immunopotentiators was examined in histocompatible animals bearing a small burden L1210 leukemic cells. When combined with Con A-bound vaccine, a streptococcal immunopotentiator, OK-432 (NSC B116209), prepared from Streptococcus pyogenes, was potent in antitumor therapy and resulted in a number of cured animals. Administration of either Con-A-bound vaccine or OK-432 alone did not produce any beneficial effect on leukemic animals. The enhanced therapeutic response was dependent on the effectiveness of the dose and timing of the administration of OK-432 when given after vaccination. Combined modality of Con A-bound L1210 vaccine and OK-432 was not effective in animals bearing P388 murine leukemic cells, which indicates specificity of therapeutic response. In enhancing the therapeutic potency of Con A-bound leukemia vaccine, pyran copolymer (NSC 46015) was as effective as OK-432, whereas Bacillus Calmette-Guérin and Corynebacterium parvum were far less effective. When combined with OK-432, therapeutic response to Con A-bound L1210 vaccine was much greater than response to glutaraldehyde-, mitomycin C-, or Vibrio cholerae neuraminidase-treated L1210 vaccine.