Innate and Adaptive Immunity
We live in a world where microorganisms dominate. The immune system, the body's main defense system against cancer and infections, consists of innate immunity and adaptive immunity. The innate immune system is responsible for rapid, non-specific response to any foreign body. A simple example is white blood cells rushing to the site of a laceration to stave off infection. The adaptive immune system is responsible for antigen-specific immune responses and includes certain immune cells (like B cells and T cells) that are designed to recognize and attack that antigen.
1. What are the basic components of Innate and Adaptive Immunity?
The innate and adaptive immune responses play a major role in cancer prevention, anti-infections and also retarding cancer progression. The basic components of the innate and adaptive immune responses to infection and cancer are depicted in Fig.1. Innate immune response includes dendritic cells, which are involved in antigen presentation, neutrophils and phagocytes, and activation of the complement system. The adaptive immune response leads to activation of B lymphocytes, which produce specific antibodies and T lymphocytes involved in cytokine release, direct cytotoxicity and retention of memory for the antigens.
Fig. 1 The basic components of the innate and adaptive immune responses to infection and cancer
*This diagram is derived from reference 1.
2. What are the Difference between Innate and Adaptive Immunity?
Innate immunity presents right from the birth and recognizes molecular structures that are unique to microbes via pattern recognition receptors (PRR). The innate immune system aims to eliminate microbes and other foreign particles by physical barriers, complement, phagocytosis and cytotoxic killing. Adaptive immunity, also known as acquired immunity, is acquired during the course of life. A key role of the adaptive immune system is building a memory bank of antigens for easier recognition and attack of the same antigens in the event of future exposure. We summarize the difference between innate and adaptive immunity on the following table.
| |
Innate Immunity |
Adaptive/Acquired Immunity |
| Definition |
Innate immunity is the inborn resistance against infections that an individual possesses right from birth, due to his genetic or constitutional markup. |
Acquired immunity is the resistance against infecting foreign substances that an individual acquires or adapts during the course of life. |
| Origin |
Prior exposure to the antigen is not required. It is present before the first exposure to microbial antigen. |
Develops during lifetime following the antigenic exposure. |
| Activity |
Always present. |
Normally silent but triggers often exposure to pathogens. |
| Diversity |
Diversity is limited; It is active only against a limited repertoire of antigens. |
Adaptive immunity is more varied and involves specialized immune responses. |
| Specificity |
Non-specific defends against any pathogen upon first exposure. |
Antigen specific-responds to specific pathogen on 2nd or latter exposure. |
| Functional against |
General microbes (bacteria, fungi, parasites), etc, Chemical irritants, burns, tissue injury, etc. |
Microbes, as well as nonmicrobial substance, called antigen. |
| Response time |
Immune response occurs in minutes. |
Takes days to generate immune response. |
| Potency |
It has a limited and lower potency. |
It has highly potent immune response. |
| Target Antigens |
Innate immunity develops against antigens that are shared by many microbes (called pathogens-associated molecular patterns). |
Acquired immunity develops against antigens that are specific for each microbe. |
| Host Cell Receptors |
Host cell receptors of innate immunity (called pattern recognition receptors) are non-specific, e.g. Toll-like receptor. |
Host cell receptors are specific, e.g. T cell receptor and B cell immunoglobulin receptor. |
| Immunological Memory |
Absent
It reacts with equal potency upon repeated exposure to same pathogen. |
Present
Presence of memory cells triggers a faster and potent response when re-exposed to same pathogen. |
| Heritance |
Innate immunity is inheritable. |
Passive acquired immunity is heritable from mother to neonates for a brief period after birth. |
3. Featured Targets Related to Innate and Adaptive Immunity
CUSABIO collects and lists the related molecules/targets of innate and adaptive immunity, click to see all the related molecules/targets and research reagents of them.
● T Cell
● B Cell
● NK Cell
● Adhesion Molecules
● Co-stimulatory & Co-inhibitory Molecules
References
[1] Mehta K, Patel K and Parikh RA. Immunotherapy in genitourinary malignancies [J]. J Hematol Oncol. 2017, 10(1):95. Published 2017 Apr 24.
