CD4+ T Cells and Antitumor Immunity - MHC Class II and Immunotherapy

MHC Class II and Immunotherapy

Many of the afore mentioned mechanisms by which CD4+ cells play a role in tumor immunity are dependent on phagocytosis of tumors by APCs and subsequent presentation on MHC class II. It is rare that tumor cells will express sufficient MHC class II to directly activate a CD4+ T cell. As such, at least two approaches have been investigated to enhance the activation of CD4+ T cells. The simplest approach involves upregulation of adhesion molecules, thus extending the presentation of antigens by APC (reference?). (Chamuleau et al., 2006) A second approach involves increasing the expression of MHC class II in tumor cells. This technique has not been used in vivo, but rather involves injection of tumor cells which have been transfected to express MHC class II molecules, in addition to suppression of the invariant chain (Ii, see below) through antisense technology. (Qiu, 1999) Mice vaccinated with irradiated strains of these cells show a greater immune response to subsequent challenge by the same tumor, without the upregulation of MHC class II, then do mice vaccinated with irradiated, but otherwise unaltered tumor cells. These findings signify a promising area of future research in the development of cancer vaccines.