Immune function tests include the following, such as rheumatological tests, autoantibody tests, lymphocyte subsets tests, immunoglobulin measurements and immunoelectrophoresis. The function of immune system is performed by T lymphocytes or B lymphocytes, T lymphocytes perform cellular immunity and B lymphocytes perform humoral immunity, T lymphocytes are mainly used to kill bacteria or viruses or foreign substances through cytotoxic effect, B lymphocytes are mainly differentiated into plasma cells to synthesize antibodies and fight against some substances. Immune function tests can be performed on immunoglobulins, subsets of lymphocytes, or subsets of B lymphocytes, such as CD3, CD4, and other differentiated antigens.