In immunology,an antigen (Ag) is a molecule,moiety,foreign particulate matter,or an allergen,such as pollen,that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.
An antibody (Ab) or immunoglobulin (Ig) is a large,Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses,including those that cause disease. Antibodies can recognize virtually any size antigen with diverse chemical compositions from molecules. Each antibody recognizes one or more specific antigens. Antigen literally means "antibody generator",as it is the presence of an antigen that drives the formation of an antigen-specific antibody. Each tip of the "Y" of an antibody contains a paratope that specifically binds to one particular epitope on an antigen,allowing the two molecules to bind together with precision. Using this mechanism,antibodies can effectively "tag" a microbe or an infected cell for attack by other parts of the immune system,or can neutralize it directly.
In immunology,autoimmunity is the system of immune responses of an organism against its own healthy cells,tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". Prominent examples include celiac disease,diabetes mellitus type 1,Henoch–Schönlein purpura,systemic lupus erythematosus,Sjögren syndrome,eosinophilic granulomatosis with polyangiitis,Hashimoto's thyroiditis,Graves' disease,idiopathic thrombocytopenic purpura,Addison's disease,rheumatoid arthritis,ankylosing spondylitis,polymyositis,dermatomyositis,and multiple sclerosis. Autoimmune diseases are very often treated with steroids.
B cells,also known as B lymphocytes,are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. When a naïve or memory B cell is activated by an antigen,it proliferates and differentiates into an antibody-secreting effector cell,known as a plasmablast or plasma cell. In addition,B cells present antigens and secrete cytokines. In mammals B cells mature in the bone marrow,which is at the core of most bones. In birds,B cells mature in the bursa of Fabricius,a lymphoid organ where they were first discovered by Chang and Glick,which is why the B stands for bursa and not bone marrow,as commonly believed.
The T helper cells (Th cells),also known as CD4+ cells or CD4-positive cells,are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considered essential in B cell antibody class switching,breaking cross-tolerance in dendritic cells,in the activation and growth of cytotoxic T cells,and in maximizing bactericidal activity of phagocytes such as macrophages and neutrophils. CD4+ cells are mature Th cells that express the surface protein CD4. Genetic variation in regulatory elements expressed by CD4+ cells determines susceptibility to a broad class of autoimmune diseases.
Immunotherapy or biological therapy is the treatment of disease by activating or suppressing the immune system. Immunotherapies designed to elicit or amplify an immune response are classified as activation immunotherapies, while immunotherapies that reduce or suppress are classified as suppression immunotherapies. Immunotherapy is under preliminary research for its potential to treat various forms of cancer.
A cancer vaccine,or oncovaccine,is a vaccine that either treats existing cancer or prevents development of cancer. Vaccines that treat existing cancer are known as therapeutic cancer vaccines or tumor antigen vaccines. Some of the vaccines are "autologous",being prepared from samples taken from the patient,and are specific to that patient.
The regulatory T cells (Tregs or Treg cells),formerly known as suppressor T cells,are a subpopulation of T cells that modulate the immune system,maintain tolerance to self-antigens,and prevent autoimmune disease. Treg cells are immunosuppressive and generally suppress or downregulate induction and proliferation of effector T cells. Treg cells express the biomarkers CD4,FOXP3,and CD25 and are thought to be derived from the same lineage as naïve CD4+ cells. Because effector T cells also express CD4 and CD25,Treg cells are very difficult to effectively discern from effector CD4+,making them difficult to study. Research has found that the cytokine transforming growth factor beta (TGF-β) is essential for Treg cells to differentiate from naïve CD4+ cells and is important in maintaining Treg cell homeostasis.
Cancer immunotherapy (immuno-oncotherapy) is the stimulation of the immune system to treat cancer,improving the immune system's natural ability to fight the disease. It is an application of the fundamental research of cancer immunology (immuno-oncology) and a growing subspecialty of oncology.
The adaptive immune system,also known as the acquired immune system,or specific immune system is a subsystem of the immune system that is composed of specialized,systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system is one of the two main immunity strategies found in vertebrates.
Cluster of differentiation 40,CD40 is a type I transmembrane protein found on antigen-presenting cells and is required for their activation. The binding of CD154 (CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of downstream effects.
B-lymphocyte antigen CD19,also known as CD19 molecule,B-Lymphocyte Surface Antigen B4,T-Cell Surface Antigen Leu-12 and CVID3 is a transmembrane protein that in humans is encoded by the gene CD19. In humans,CD19 is expressed in all B lineage cells. Contrary to some early doubts,human plasma cells do express CD19,as confirmed by others. CD19 plays two major roles in human B cells:on the one hand,it acts as an adaptor protein to recruit cytoplasmic signaling proteins to the membrane;on the other,it works within the CD19/CD21 complex to decrease the threshold for B cell receptor signaling pathways. Due to its presence on all B cells,it is a biomarker for B lymphocyte development,lymphoma diagnosis and can be utilized as a target for leukemia immunotherapies.
CD70 is a protein that in humans is encoded by CD70 gene. CD70 is also known as a ligand for CD27.
Understanding of the antitumor immunity role of CD4+ T cells has grown substantially since the late 1990s. CD4+ T cells (mature T-helper cells) play an important role in modulating immune responses to pathogens and tumor cells,and are important in orchestrating overall immune responses.
Lymphocyte-activation gene 3,also known as LAG-3,is a protein which in humans is encoded by the LAG3 gene. LAG3,which was discovered in 1990 and was designated CD223 after the Seventh Human Leucocyte Differentiation Antigen Workshop in 2000,is a cell surface molecule with diverse biological effects on T cell function but overall has an immune inhibitory effect. It is an immune checkpoint receptor and as such is the target of various drug development programs by pharmaceutical companies seeking to develop new treatments for cancer and autoimmune disorders. In soluble form it is also being developed as a cancer drug in its own right.
The following outline is provided as an overview of and topical guide to immunology:
The Immune Response Corporation (IRC) was a pharmaceutical company that worked in the development of immunotherapeutic products. The firm was founded by Jonas Salk and Kevin Kimberlin when Kimberlin,"asked Salk to become lead scientific advisor for a new biotech company specializing in 'anti-idiotypes,' a novel vaccine technology." Salk called the proposal "liberating."
B10 cells are a sub-class of regulatory B cells that are involved in inhibiting immune responses in both humans and mice. B10 cells are named for their ability to produce inhibitory interleukin:Interleukin-10 (IL-10). One of their unique abilities is that they suppress the innate and adaptive immune signals,making them important for regulating the inflammatory response. Like the B cell,the B10 cell requires antigen specific binding to the surface of CD5 receptor to elicit a response from the T cell. Once an antigen binds to the CD19 receptor,immediate downregulation in B-cell receptor (BCR) signal expression occurs and mediates the release of IL-10 cytokines. In mice and humans,B10 cells are distinguishable in their expression of measurable IL-10 due to the lack of unique cell surface markers expressed by regulatory B cells. However,IL-10 competence is not limited to any one subset of B cells. B10 cells do not possess unique phenotypic markers or transcription factors for further identification. B10 cells predominantly localize in the spleen,though they are also found in the blood,lymph nodes,Peyer's patches,intestinal tissues,central nervous system,and peritoneal cavity. B10 cells proliferate during inflammatory and disease responses.
Whole-cell vaccines are a type of vaccine that has been prepared in the laboratory from entire cells. Such vaccines simultaneously contain multiple antigens to activate the immune system. They induce antigen-specific T-cell responses.
Freda Kathryn Stevenson is a British immunologist and Professor at the University of Southampton. She was elected a Fellow of the Academy of Medical Sciences in 2000,and was the first British researcher to be awarded the American Society of Hematology Henry M. Stratton Medal.
