Antigenic role of sialic acid in the antitumor activity of a GM3 ganglioside-based vaccinein B16 mouse melanoma

MARIANO R. GABRI; MARCELO D. GUTHMAN; GISELLE V. RIPOLL; DANIEL F. ALONSO; LEONARDO FAINBOIN; DANIEL E. GOMEZ

New Orleans, LA. Estados Unidos.

Congreso; 92st. Annual Meeting, American Association for Cancer Research (AACR); 2001

American Association for Cancer Research (AACR)

We have reported previously a GM3 based vaccine conjugated hydrophobically to OMP proteins, named GM3-VSSP. This vaccine has shown a potent antitumor effect accompanied with a strong antibody response against B16 murine melanoma cells. Ganglioside GM3 has been reported in several melanoma cells but not in carcinoma cells.  In this work we analyze the immunotherapheutic properties of GM3-VSSP vaccine over B16 cells and F3II murine mammary carcinoma cells. FACS analysis shown the presence of GM3 in B16 cells and the absence in F3II cells. To evaluate the antitumor properties of GM3-VSSP vaccine, mice were vaccinated four times with GM3-VSSP vaccine (120 mg GM3) every two weeks prior to the injection of 1x104 or 2x105 B16 and F3II tumor cells respectively. No differences was seen in latency between groups, treated and controls of F3II challenged mice. In contrast, mice challenged with B16 melanoma cells immunized only with the immunological adjuvant showed a significant latency disminution than treated mice. In order to elucidate the type of antigen recognized by the serum we incubate B16 cells with BFA that diminished the concentration of GM3 in cell membrane. Treated and untreated cells shown a distinct positive staining, suggesting that GM3 ganglioside is not the only antigen recognized by the immune serum. We treated fixed B16 monolayer cells with 0,1 UI/ml of Neuraminidase.  Lost of reactivity were seen with this treatment indicating that this residue is a key antigen in the humoral response after the vaccination with GM3-VSSP.