Inoculation of human interleukin-17 gene-transfected Meth-A fibrosarcoma cells induces T cell-dependent tumor-specific immunity in mice.

OBJECTIVE

The biological activities of interleukin-17 (IL-17), a newly cloned cytokine, have not been fully elucidated. The present study was designed to assess the in vitro and in vivo effect of transfecting the IL-17 gene into tumor cells.

METHODS

A complementary DNA (cDNA) encoding human IL-17 (hIL-17) was obtained by polymerase chain reaction amplification from the human CD4+ T cell cDNA library and inserted into the plasmid pRc/cytomegalovirus to construct an expression vector for the hIL-17 gene. Murine Meth-A fibrosarcoma cells were transfected with the hIL-17 gene using the lipofectin method. The hIL-17 gene-expressing clone (Meth-A/IL-17) was selected and analyzed for cytokine expression by Northern blot.

RESULTS

There was no significant difference in the in vitro proliferation rate among parent Meth-A, cells transfected with vector alone and Meth-A/IL-17 cells. When the tumor cells were transplanted subcutaneously into BALB/c nude (nu+/nu+) mice, there was no difference in in vivo growth rates among the three cell lines. Challenge with tumor cells in conventional BALB/c mice, however, resulted in the rejection of Meth-A/IL-17 cells, but the other two lines did grow. After immunization with Meth-A/IL-17 cells, the mice were rechallenged by parent Meth-A or syngeneic MOPC-104E plasmacytoma cells; the immunized mice rejected the Meth-A cells, but not the MOPC-104E cells. Injecting the anti-thy 1,2 (CD90), anti-CD4 or anti-CD8 monoclonal antibody into conventional BALB/c mice resulted in the resumption of in vivo growth of Meth-A/IL-17 cells, but injecting the anti-asialo GM1 antibody did not. Furthermore, flow cytometric analysis demonstrated a significant increase in the expression of major histocompatibility complex (MHC) class I and class II antigens and lymphocyte function-associated antigen-1 on Meth-A/IL-17 cells.

CONCLUSION

Meth-A cells transfected with the hIL-17 gene can induce tumor-specific antitumor immunity by augmenting the expression of MHC class I and II antigens, and both CD4+ and CD8+ T cells may play important roles in inducing antitumor immunity, suggesting the possibility of developing a tumor vaccine incorporating IL-17-transfected tumor cells.