Are MHC class II-restricted cytotoxic T lymphocytes important?

Although most cytotoxic T lymphocytes (CTL) are MHC class I restricted and most helper T cells class II restricted, some CTL are MHC class II restricted. The function of these cells is unclear. Here, Eric Braakman and co-workers suggest that they are an important regulatory influence, appearing late in the immune response and destroying cells presenting antigen in the context of class II molecules. The elimination of these cells inhibits the generation of the helper T response and consequently terminates the immune response to that antigen.