immunostimulants

Immunostimulants are substances that enhance the immune system's ability to respond to threats. They can activate innate immune cells such as macrophages and natural killer cells, promote dendritic cell maturation and antigen presentation, and increase cytokine and chemokine production. Immunostimulants may be endogenous mediators like body-produced cytokines or exogenous agents including microbial components, plant or fungal extracts, and synthetic compounds that modulate immune signaling. They differ from vaccines, which aim to elicit specific adaptive immunity, though many immunostimulants are used as adjuvants to improve vaccine responses.

Common examples include cytokines such as interleukins and interferons, topical or systemic agents like imiquimod (a TLR7 agonist) and levamisole, and various adjuvants added to vaccines. Immunostimulants also appear in cancer therapy, such as Bacillus Calmette-Guérin (BCG) for bladder cancer. Natural products such as beta-glucans have been studied for their immunostimulatory activity, with evidence of benefit varying by indication.

In infectious diseases and immunodeficiency, immunostimulants may be used to support immune responses, though benefits are often context-dependent and time-limited. Safety concerns include excessive inflammation and risk of autoimmunity; adverse effects can limit use to specific indications and patient groups.

Regulatory status varies by agent and jurisdiction. Some immunostimulants are approved therapies for particular conditions, others are research agents or dietary supplements. Dosing, monitoring, and patient selection are important to balance potential benefits against risks.