Enhanced expression of iNOS intratumorally and at the immunization site after immunization with IFNgamma-secreting rat glioma cells.

Nitric oxide (NO) can modulate both tumor growth and antitumor immune responses. In order to elucidate the mechanism of curative therapeutic immunization with IFNgamma-producing glioma cells, we examined the expression of inducible nitric oxide synthase (iNOS) in tissue sections from immunized animals. There was a significantly enhanced iNOS expression both intratumorally and at the immunization site. Although the mechanisms behind this dual expression of iNOS most probably are different, our results suggest a role for NO in both the induction and execution of the antitumor response.