CD200 expression on tumor cells inhibits the ability of human lymphocytes to eradicate tumor cells by interaction of CD200 with its receptor alters cytokine profiles from Th1 cytokines like (IFNS, IL2) to Th2 cytokines (IL10, IL4) in mixed lymphocyte reactions, and results in the induction of regulatory T cells, which are thought to slow down tumor-specific effector T cell immunity. This evidence concerns the gene IL10 and neoplasm.