The immune system is an interlinked set of biological processes that protect an individual from diseases. It can detect and respond to a wide variety of microbes, including viruses, bacteria, parasitic worms, and cancer cells.
The immune system consists of several types of cells, each with different functions that work together to ensure that pathogenic microbes that enter the body are swiftly eradicated. The immune system is divided into two main parts:
The innate immune system
The adaptive immune system
The cells from the innate immune system function to eliminate the invading pathogen soon after entry and is, therefore, the first line of defense. The cells of the adaptive immune system then interact with these cells to create a memory of the pathogen. If the body encounters the pathogen in the future, the memory cells produce antibodies that aid in eliminating the microbe. This is also the basis of how vaccines work.
Immune cells regulate inflammation and anti-microbial processes through the secretion of immune modulators known as cytokines and chemokines. The five different types of immune cells are:
Monocytes and macrophages
Multiple disorders of the immune system exist, with many of them being attributed to single nucleotide polymorphisms (SNPs) in the genes encoding certain immune modulators. Some conditions are less pervasive such as pollen allergy, while others are severe, such as genetic conditions that destroy the function of an entire group of immune cells. Further, evidence suggests that a dysregulated inflammatory response plays a pivotal role in cancer development.
Research suggests that chronic inflammation underpins several cancers. Normally, pro-inflammatory cytokine function is counteracted by the release of anti-inflammatory cytokines to restore balance. However, studies reveal that SNPs in the gene encoding a key anti-inflammatory marker may be associated with the development of colon cancer 2, prostate cancer 3, breast cancer 4, and non-small-cell lung cancer 5. Therefore, there is a convincing association between SNPs in anti-inflammatory mediators and a predisposition to cancer development.
Normally, histamine plays a key role in the inflammatory process of allergies and asthma. In severe or chronic cases of asthma, histamine plays a central role in its pathophysiology. Genetic polymorphisms in genes associated with the histamine pathway affect its production and degradation 6. For example, SNPs have been detected in the gene which is responsible for the degradation of histamine after its release 7. This allows histamine to linger in the airways which further contributes to bronchoconstriction (tightening of the airways). Different SNPs in the same gene have surprisingly been linked to migraine susceptibility 8.
Various enzymes play a supportive role in facilitating reactions in several immune cells. These reactions may aid in either promoting the secretion of an immune modulator or in the clearance of harmful substances. Recent research has found that SNPs in the genes encoding enzymes with clearance functions play a key role in the growth of tumors and have been marked as a potential therapeutic target for cancer therapy 9.