Definition of Immunomodulator:
Immunomodulators are agents that alter the immune response by augmenting (immunostimulants) or reducing (immunosuppressants) the ability of the immune system to produce antibodies or sensitized cells that recognize and react with the antigen that initiated their production. Immunomodulators include corticosteroids, cytotoxic agents, thymosin, and immunoglobulins [Mosby2009]. Note, however, that stimulating one aspect of the immune system tends to suppress other aspects and vice versa, as is seen in the TH1 vs TH2 response that is mediated by cytokines [ORWJr].