Overview of Immune System
The immune system provides a multi-faceted natural defense mechanism in mammals against invading infectious pathogens, such as bacteria, viruses and parasites, and also plays a critical role in recognizing and preventing abnormal cell expansion such as cancer. The immune system is comprised of a variety of cell types and soluble factors, working in concert, to generate an immediate (hours to days) first-line response to pathogens, termed innate immunity as well as a more specialized longer duration (weeks) response, termed adaptive immunity with immunological memory.
- Innate immunity develops rapidly in the face of pathogen invasion resulting in a generalized, short-term immune response, i.e., cytokine and NK cell activation and expansion.
- Adaptive immunity requires a longer period of time (days to weeks) to become sensitized, expand, and differentiate into mature immune effectors, but results in a more highly specific and powerful activity conferring long-term immunity.
Under normal conditions, the innate and adaptive immune pathways provide ongoing immune surveillance and protection function for the body. Many pathogens and cancer cells, however, have evolved mechanisms, i.e., mutations, immune suppression, to evade or circumvent the immune system and, in this manner, chronic infectious diseases and cancers can become established. Current vaccines are generally administered prophylactically, i.e., before encountering the disease agent, and are primarily designed to produce specific antibodies that are able to counteract the invading pathogen before it can cause disease in the host. However, treatment of established diseases, e.g., chronic infections and cancer, requires a much more powerful immune response to overcome an existing disease process, not only by better recognition of the disease target, but also through more effective elimination of the causative agent. Therefore, efficient and broadly effective therapeutic immunostimulants are essential to boost these specialized immune effector systems in the context of an ongoing disease process.
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