What Is a Cytokine?

A class of compounds synthesized and secreted by immune cells (such as monocytes, macrophages, T cells, B cells, NK cells, etc.) and certain non-immune cells (endothelial cells, epidermal cells, fibroblasts, etc.) upon stimulation. Widely biologically active small molecule proteins. Cytokines generally regulate cell growth, differentiation, and effects by binding corresponding receptors, and regulate immune responses. Cytokine (CK) is a low-molecular-weight soluble protein that is induced by a variety of cells by immunogens, mitogens, or other stimulants. It has the ability to regulate innate and adaptive immunity, hematogenesis, cell growth, APSC pluripotent cells, and damage. Tissue repair and other functions. Cytokines can be divided into interleukins, interferons, tumor necrosis factor superfamily, colony-stimulating factors, chemokines, growth factors, and so on.

Cytokine (CK) is a small molecule polypeptide or glycoprotein synthesized and secreted by a variety of tissue cells (mainly immune cells). Cytokines can mediate cell-cell interactions and have a variety of biological functions, such as regulating cell growth, differentiation and maturity, function maintenance, regulating immune response, participating in inflammatory responses, wound healing, and tumor growth and growth. Initially, people were not clear about the nature of cytokines, so they were named according to their biological activities, resulting in multiple names for the same cytokine. Later, people realized that cytokines are mainly synthesized by leukocytes, and they mainly mediate the interaction between leukocytes. Therefore, these factors are collectively named interleukin (IL), and they are named with Arabic numerals in the order of discovery. Such as IL-1, IL-2, IL-3 and so on. Since Lssac discovered interferon in 1957, more than 200 cytokines have been discovered to date. People call all interleukins, interferons, tumor necrosis factors, hematopoietic factors, growth factors, chemokines and so on collectively called cytokines. The rapid development of modern genetic engineering and cell engineering technology provides technical conditions for the discovery of more cytokines and the study of their structure and function. The research results of cytokines provide a scientific basis for clinical prevention, diagnosis, and treatment of diseases, especially The use of cytokines to treat tumors, infections, hematopoietic dysfunction, and autoimmune diseases has a very broad application prospect ^[1]

Recombinant cytokine requirements:

1. Authenticity: Recombinant protein products are consistently analyzed by N-terminal amino acid sequence; if necessary, SDS-PAGE, RP-HPLC, and mass spectrometry (MS) are used to check their authenticity.

2. Purity: Apply SDS-PAGE and RP-HPLC methods to analyze product purity.

3. Biological activity: Perform corresponding in vitro or in vivo activity tests.

4. Protein content: detected by ultraviolet spectrum analysis, SDS-PAGE electrophoresis; if necessary, quantify the standard protein solution by HPLC.

5.

(1) Different classification according to the type of cells producing cytokines

In order to maintain the physiological balance of the body, resist the invasion of pathogenic microorganisms, and prevent tumorigenesis, many cells of the body, especially

Cytokines play a biological role by binding to the corresponding cytokine receptors on the cell surface. Cytokines and their receptors initiate complex intracellular molecular interactions that ultimately cause cells

Many cytokines have the following common action characteristics.

(1) Most cytokines are glycoproteins with a mass of less than 25kDa, and those with low mass, such as IL-8, are only 8kDa. Most cytokines exist as monomers, and a few cytokines, such as IL-5, IL-12, M-CSF, and TGF-, play biological roles in the form of dimers. Most genes encoding cytokines are single-copy genes (except IFN-), and consist of 4-5 exons and 3-4

From the molecular structure point of view, cytokines are small peptides, most of which are composed of about 100 amino acids. Cytokines can exert their biological effects only by specifically binding to cytokine receptors on the surface of target cells. These effects include promoting the proliferation and differentiation of target cells, enhancing anti-infective and tumor-killing effects, and promoting or inhibiting other cytokines. Synthesis, promote inflammatory processes, affect cell metabolism and so on. These effects of cytokines have network characteristics, that is, each cytokine can act on multiple cells; each cell can be regulated by multiple cytokines; and different cytokines have synergistic or restrictive effects. This constitutes a complex cytokine immunoregulatory network. What people know about this network is far from clear.

In recent years, genetically modified cytokines have made remarkable achievements in clinical application as a new type of biological response regulator. For example, the earliest clinical use of interferon alpha is in the treatment

Cytokines have other biological effects, such as promoting apoptosis and promoting wound tissue repair. Some cytokines in the tumor necrosis factor superfamily can directly kill or induce apoptosis of target cells. For example, TNF-a and LT- can kill target cells or tumor cells infected by the virus. Transforming growth factor-B (TGF-B) can stimulate fibroblasts and osteoblasts to promote the repair of damaged tissues. Epidermal growth factor can promote the proliferation of epithelial cells, fibroblasts and endothelial cells, and promote skin wound healing ^] .