Correlations between humoral immunity and successful chemotherapy-immunotherapy

Experiments were designed to evaluate the characteristics of the humoral immune response induced by active immunotherapy, both specific (neuraminidase-treated tumore cells) and nonspecific (Bacillus Calmette-Guérin organisms), in the L1210-C57BL/6 X DBA/2F tumor-host system. Tumor burden was minimized with chemotherapy (1,3-bis-(2-chloroethyl)-1-nitrosourea) prior to immunotherapy. A marked increase in the concentration of serum immunoglobulins (immunoglobulin M, immunoglobulin G, and immunoglobulin G) was observed following successful therapy. The highest concentration of these immunoglobulins was found in mice given both Vibrio cholerae neuraminidase-treated cells and B. Calmette-Guérin after chemotheraphy. Tumor-specific immunoglobulin M and immunoglobulin G, as measured by indirect immunofluorescnece, were detected in the sera during the course of successful therapy. Positive immunofluorescence was not observed with progressive sera. Complement-dependent cytotoxic activity against L1210 cells was first detected 5 days after immunotherapy, and increased for several weeks. A high level of cytotoxic activity correlated with successful therapy, whereas low levels were foun in treated mice with recurring tumors. Serum cytotoxicity was not detected in untreated mice with progressively growing tumor.