Immunomodulator drugs: Mechanism of action and systemic effects.

Immunomodulatory drugs or immunomodulators have now become mainstream therapeutic medicine in the field of pharmaceutical industry. They represent a unique class of drug products that are natural or synthetic substances, holding tremendous potential to modulate both innate and adaptive immunity, either by boosting or repressing the immune response. Immunomodulators have shown therapeutic benefits in the treatment of various infections, cancer, autoimmune diseases, as well as in organ transplantation. These drugs are classified into two major categories, immunostimulant and immunosuppressant drugs. Immunostimulant drugs can enhance the body's immune system by increasing the activity of lymphocytes and by producing various serum antibodies and cytokines to fight against various infections, tumors, primary or secondary immunodeficiency. In contrast, immunosuppressant drugs are used to suppress or reduce the immune response during organ transplants, chronic inflammation, and in autoimmune diseases such as rheumatoid arthritis, pemphigus, and lupus erythematosus. This chapter provides a cross-sectional perspective on the mechanism of immunostimulatory as well as of immunosuppressive therapeutics and their systemic effects on the human body.