CD37 controls both humoral and cellular immune responses. They function in the humoral immunity component of the adaptive immune system by secreting antibodies. Glucocorticoids also suppress the humoral immunity, thereby causing a humoral immune deficiency. Antibodies are major components of humoral immunity. Complement is the major humoral component of the innate immune response. In other words, immunogenicity is the ability to induce a humoral and/or cell-mediated immune responses. One set of innate immune mechanisms is humoral, such as complement activation. They can also regulate specific humoral and cell-mediated immunity. Exotoxins are extremely immunogenic meaning that they trigger the humoral response (antibodies target the toxin). This prolific production of antibodies is an integral part of the humoral immune response. The mononuclear phagocyte system is part of both humoral and cell-mediated immunity. The production of antibodies is the main function of the humoral immune system. Endocrine organs are activated to release their hormones by humoral, neural or hormonal stimuli. Several studies found that chronic stressors (like trauma or loss) suppressed cellular and humoral immunity. Passive immunity is the transfer of active humoral immunity of ready-made antibodies.