Immunology encompasses the study of all aspects of the immune system. The study of immunology is clinically relevant because an increased understanding of how the immune system functions will allow researchers to develop better treatments for both infectious and autoimmune diseases. Immunological research can also be targeted toward finding ways to harness the immune system to protect against the development of various cancers. Various proteins, including cytokines, chemokines, interferons and interleukins, are involved the various pathways associated with the immune system.
Cytokines are soluble extracellular proteins that act as key modulators of both innate and adaptive immune responses. They are composed of two major subfamilies, chemokines and interleukins, which act as chemotactic cytokines and mediators of leukocyte communication, respectively. Cytokines are released by leukocytes in response to stimuli and regulate many biological processes, including cell activation, cell migration, cell proliferation, cell death, differentiation, angiogenesis, development and tissue repair.
Chemokines are a family of cytokines that have the ability to induce directed chemotaxis in nearby cells. Homeostatic chemokines are involved in controlling the migration of cells during tissue maintenance and development. These chemokines also participate in immune surveillance by directing lymphocytes to the lymph nodes. Pro-inflammatory chemokines are induced by an immune response and recruit immune cells to sites of infection. Their release is stimulated by cytokines in response to bacterial infections, viruses and/or physically damaging agents.
Chemokines can be divided into four classes based on the arrangement of the conserved cysteine residues of the mature proteins. Members of the CC group, which contain two adjacent cysteines near the amino terminus, induce the migration of monocytes, as well as NK cells and dendritic cells. The CXC group contains two N-terminal cysteines separated by one amino acid and is involved in the migration of neutrophils and lymphocytes. C chemokines, the third group, contain one N-terminal cysteine and one downstream cysteine. Members of this group attract T cell precursors to the thymus. The final group, CX3C chemokines, contains three amino acids between two cysteines and serves as adhesion molecules.
Interferons (IFNs) are a type of cytokine that facilitate communication between cells to trigger the immune system. These proteins are synthesized and released by host cells in response to either pathogens or tumor cells. In addition to their ability to interfere with viral replication, IFNs also activate immune cells and up-regulate antigen presentation to T lymphocytes. Ten distinct IFNs have been identified in mammals and are classified among three IFN classes, Type IFN, Type II IFN and Type III IFN.
Interleukins (ILs) are a large group of cytokines that mediate cell-to-cell communication. They display a wide spectrum of biological activities including cell activation, differentiation, proliferation and motility. The majority of interleukins are produced by T helper cells, as well as by monocytes, macrophages and endothelial cells. ILs promote the development and differentiation of T-, B- and hematopoietic cells.
A deeper understanding of the various functions of cytokines, chemokines, interferons and interleukins in the body’s defense against pathogens, as well as the development autoimmune diseases, may one day lead to the development of better treatments and possibly even cures for a variety of diseases. Antibodies against these various factors are vital to the study of immunology, and antibody manufacturers are designing product lines to address the needs of this growing research area.