The activity of CD8+T cells can also be greatly enhanced and can have a very strong cytotoxic effect.CD8+ T cells attack and destroy virus-infected CD23+B cells in body fluids and lymph nodes, inhibit their abnormal proliferation, release excessive cytokines and simultaneously cause symptoms of infectious mononucleosis (IM) [42], an EBV-associated disease. This evidence concerns the gene FCER2 and infectious mononucleosis.