Immunostimulants are substances that modulate the immune system by stimulating the function of one or more of the system’s components. There are two types. Specific immunostimulants, such as vaccines, stimulate an immune response to one or more specific antigenic types. In contrast, non-specific immunostimulants do not have any antigenic specificity but can act as general stimulants that enhance the function of certain types of immune cells.
In terms of immunostimulant substances used in the general human population, it is vaccines which are most commonly employed. Vaccines are used to stimulate a protective immune response to antigens from specific pathogens. The influenza vaccine, for example, uses several antigens from different strains of the flu virus. People who are vaccinated are then protected against infection from those particular strains.
Another type of immunostimulant called an adjuvant is often used in conjunction with vaccines. Adjuvants are a type of non-specific immunostimulant. Administering an adjuvant along with a vaccine helps generate a stronger protective response to the antigens in the vaccine, providing a better degree of protection against the pathogen. One example of an adjuvant is alum, which is often used in human vaccines. Alum is made from aluminum salts such as aluminum hydroxide and aluminum phosphate.
Many chemical substances produced by the human body function as immunostimulants. Cytokines are a type of immunostimulant which are produced by cells of the immune system, and many have a role in enhancing immune function. In addition, some female sex hormones, as well as granulocyte macrophage colony-stimulating factor, prolactin, and growth hormone, are known to have immunostimulant effects.
Several types of synthetic immunostimulant drugs have been manufactured. One of these is Macrokine, also known as tetrachlorodecaoxide, which has a variety of functions. Immunostimulant drugs such as Macrokine can function as adjuvants and have used in the treatment of ulcers, diabetic foot problems, and for wound dressings.
Immunostimulant nutrients are substances obtained from food or medicinal plants that have a stimulant effect on the immune system. This class of immunostimulants includes several vitamins, minerals, and other types of nutrients. One of the most well-known is Vitamin C, but although anecdotal evidence and the results of some studies indicate an immunostimulant effect, the true role of this vitamin is still not well known. Vitamin C has, however, been shown in at least one study to reduce the duration of infection with the common cold, but severity of symptoms is not reduced.
Beta-glucans are another type of immunostimulant nutrient, found in plants, fungi, and bacteria. Various types of beta-glucans occur in cellulose fibers in trees and plants, and can also be found in yeast, bacteria, and fungi. Beta-glucans have been trialed as adjuvants in cancer therapy, for wound dressing to help prevent post-surgical infection, as a treatment for radiation exposure, and in the treatment of certain types of allergy.