The Important Indicator of Immune System: Interleukin

Posted by beauty33 on June 24th, 2019

IL is short for interleukin. Interleukin is a kind of cytokines produced by many kinds of cells and used in many kinds of cells. It belongs to the same family of cytokines as hemocyte growth factor. They coordinate and interact with each other to complete hematopoiesis and immune regulation. Lnterleukin plays an important role in signaling, activating and regulating immune cells, mediating T and B cell activation, proliferation and differentiation, as well as inflammatory responses.

The function of interleukin is related to the expression and regulation of immune response, which is involved by many factors such as lymphocytes or macrophages. In the process of studying the immune response, many molecules with biological activity were found in the cell culture supernatant stimulated by mitogen. Researchers named each molecule after their measured activity, and reported nearly 100 kinds of factors for more than ten years. A comparative study using molecular biology techniques later found that many of the factors previously named for biological activity were actually the same substance with pleiotropic properties. In 1979, to avoid the confusion of naming, the second international symposium on lymphokines uniformly named the leukocyte interaction cytokines during the immune response as interleukin (IL). At present, at least 38 interleukins, named IL1 ~IL38 respectively, have been found, with complex functions, network formation and overlap. They play important roles in the maturation, activation, proliferation and immunomodulation of immune cells. In addition, they also participate in a variety of physiological and pathological reactions of the body. Here to introduce 5 kinds of interleukin below.

1. IL2

IL2 is also called T cell growth factor (TCGF). It is mainly produced by T cells and exerts its effects in the form of autocrine and paracrine. It can activate T cells and promote cytokine production, stimulate NK cell proliferation, enhance NK killing activity and generate cytokines, induce LAK cell production, promote B cell proliferation and secrete antibodies, and activate macrophages. Its receptor IL2R is composed of IL2Rα, IL2Rβ and IL2Rγ.

2. IL11

IL11 was initially found in the culture supernatant of primate bone marrow stromal cell line pu-34. It mainly generated by mesenchymal-derived adherent cell, such as bone marrow stromal cells, matrix fibroblasts, human embryonic lung fibroblasts and trophoblast cells.

The function of IL11 is similar to that of IL1, IL6, G-CSF and SCF:

1. To promote the production of B cell antibodies.

2. To promote the growth of some IL6-dependent cell lines such as TF-1.

3. Synergistic effect with IL3 and IL4 on bone marrow hematopoietic stem cells, to shorten the Go phase of stem cells.

4. Synergism with IL3 can promote the colony formation, growth and maturation of megakaryocytes in vitro, increase cell volume and the number of peripheral blood platelets.

5. IL11 can stimulate erythrocyte progenitor cells at different differentiation stages of mouse bone marrow and fetal liver.

6. To induce acute phase protein synthesis in hepatocytes.

7. It can inhibit lipoprotein lipase (LPL) activity and adipocyte differentiation, hence, it is also known as an AGIF.

3. IL12

Interleukin-12 (IL12) is a cytokine with extensive biological activity, mainly produced by activated inflammatory cells. Its main functions are:

1. To synergize IL2 to promote differentiation of CTL, NK and LAK.

2. To promote the proliferation of PHA activated T cells.

3. To promote Ig production and type conversion of B cells.

4. IL18

IL18 belongs to IL1 ligand family and its structure is similar to IL1 protein family. It is a powerful pro-inflammatory cytokine with the most characteristic function of regulating cell proliferation, differentiation and extracellular matrix formation. Therefore, IL18 plays an important role in the occurrence and development of diabetic nephropathy (DN). It can be combined with IL18BP to inhibit its biological activity. Therefore, IL18 BP is called a natural antagonist of IL18.

5. IL22

Interleukin-22 (IL22) is a member of the IL10 cytokine family discovered in recent years, originally known as IL10-related T cell differentiation induction factor (IL-TIF). IL22 was found to be highly expressed in a variety of malignant tumors of the digestive system, and the increased expression of it was associated with tumor progression and poor prognosis of patients.

Interleukins are clinically used as indicators of the state of the immune system. It also acts as a cellular signal to regulate immune system function and treat immune diseases. The study of interleukins can deepen the understanding of physiological functions of human body, deepen the understanding of the occurrence and development of diseases, and deepen the understanding of the origin of life processes.