immune response

the response of the IMMUNE SYSTEM to antigens. There are two types of immune response produced by two populations of LYMPHOCYTE . B-lymphocytes (or B-cells) are responsible for humoral immunity, producing free antibodies that circulate in the bloodstream; and T-lymphocytes (or T-cells) are responsible for cell-mediated immunity (see HELPER T-CELL , CYTOTOXIC T-CELL , SUPPRESSOR T-CELL ).