A Vet’s View: What's an immunostimulant?

The immune system functions to combat foreign invaders in the body through two basic pathways, cellular immunity and humoral immunity. Humoral immunity is the part most people have heard about, where circulating antibodies serve to neutralize invading pathogens (a pathogen is a disease-producing agent like a virus or bacterium).

The other side is cellular immunity, where cells such as macrophages, T-cells and natural killer cells, act to destroy invaders. These two sides work together in a complex and interdependent manner to keep the body healthy.

Immunostimulants can be used with a variety of different animals and are designed to increase the activity of the immune system to help fight off all pathogens. This is unlike a vaccine, which stimulates the immune system to form a lasting response to a particular antigen — making them effective when fighting a particular virus or bacteria. Non-specific increase in immune activity, on the other hand, is the hallmarks of an immunostimulant.

Sometimes immunostimulants are termed immunomodulators. This is because many immunostimulants are actually capable of down-regulating some immune pathways, while up-regulating others. For example, some are capable of increasing cellular immunity, while at the same time decreasing allergic reactions. In cases like this, the term immunomodulator may be a more accurate descriptor than immunostimulant.

Immunostimulants are derived from many different sources, but most are bacteria or viruses that are modified to not cause illness, but prompt an immune response. These agents, when injected into an animal, are incapable of disease and are recognized as foreign by the animal’s immune system. The immune system ramps up production of cells and cytokines, in order to fight what it believes is an infection.

In general, immunostimulants are not intended to fight an infection on their own, but rather act as a complement to standard medical treatment. Immunostimulants, in conjunction with routine therapy, have been shown to shorten the duration and decrease the severity of disease. This means less time in treatment and more productive, healthy time for our animals.

In addition, as antibiotic resistant bacteria become a more significant health concern, the need for other means to fight infection becomes more relevant. Immunostimulants may help animals fight minor viral infections without developing secondary bacterial infections, which would normally require antibiotics. In some cases, the immunostimulant itself may be adequate for fighting a bacterial infection without antibiotics, but a veterinarian should make this decision.

Immunostimulants are an important tool in the veterinary arsenal for fighting a diverse range of diseases from respiratory illness to dermatological issues. Treatment with an immunostimulant early in the course of disease will limit the animal’s suffering and help them recover quickly. Chronic infections, particularly those unresponsive to treatment, may also see quicker resolution with the administration of an immunostimulant.

This blog was written by Neogen’s professional services veterinarian, Dr. Joe Lyman. For more information on Neogen’s animal safety division, see our website.