ICOS and gastric cancer: ICOS was mainly expressed in activated T lymphocytes and CD45 expressed in all leukocyte; they were associated with lymphocyte activation [4]; the lower levels of these molecules might be due to some lymphocytes in a inactivated state, which involved immunosuppressive microenvironment in gastric cancer patients, and the decreased IL-13 level was thought to be responsible for the low expression of ICOS and CD45.