Effect of transgenic expression of CD40L on systemic immune protection in CD40⁺ plasmacytoma cell lines.

Transgenic expression of CD40L generates systemic immune protection in CD40⁺ plasmacytoma cell lines. Mice were vaccinated twice with sublethally irradiated MPC-11 (panel A) or S107 (panel B) cells mixed with CL7.1/mCD40L fibroblasts and challenged 2 weeks later at a distant site with live tumor cells. As a control, live tumor cells were injected in the back of nonimmunized animals. Transgenic expression of CD40L (broken lines) significantly increases tumor-free survival compared with controls (solid lines) for both MPC-11 and S107 cell lines. Data are derived from 8 animals in each group. (C) The immune response mediated by CD40L was specific. Mice vaccinated twice with S107 cells mixed with CL7.1/mCD40L fibroblasts and challenged 2 weeks later at a distant site with live MPC-11 cells (broken line) had poor tumor-free survival compared with animals challenged with the S107 cell line (solid line).