The difference between cellular and humoral immunity is in definitions and roles etc. 1.Definition: (1) Cellular immunity, also known as cell-mediated immunity, mainly refers to the T-cell-mediated immune response, which has the characteristics of inflammatory response, specific cytotoxicity with monocyte infiltration, and it is also a more effective defense response to remove intracellular parasitic microorganisms and an effective means of rejecting homologous transplants or tumor antigens. (2) Humoral immunity is an immune mechanism that uses plasma cells to produce antibodies to achieve the purpose of protection, mainly by B cells. The antigens of humoral immunity are mostly proteins and polysaccharide macromolecules with a relative molecular mass of more than 10,000, and there are different antigens on the surface of bacteria and viral particles, so all of them can cause humoral immunity. 2.Role: (1) Cellular immunity is mainly involved in the immune response to intracellular parasitic pathogenic microorganisms and the immune response to tumor cells in the immunity against infection, but also involved in delayed-type allergic reactions, and can lead to the formation of autoimmune diseases. It is also involved in the regulation of humoral immunity and transplant rejection. (2) Humoral immunity is the formation of effector B cells and memory cells by B cells stimulated by antigen with the help of T cells. The effector B cell is an immune response that is accomplished by the specific combination of a specific antibody and the corresponding antigen.