Immuno Flashcards
Mast Cells
Mast cells are very similar tobasophil granulocytes(a class ofwhite blood cells) inblood. Both are granulated cells that containhistamineandheparin, ananticoagulant. Mast cells are activated as part of a hypersensitivity response
Polymorphonuclear Cells
Nucleus with several lobes and a cytoplasm that contains granules
Basophils
Basophils are the least common of thegranulocytes, representing about 0.5% to 1% of circulatingwhite blood cells.[3]However, they are the largest type of granulocyte. They are responsible for inflammatory reactions during immune response, as well as in the formation of acute and chronic allergic diseases, includinganaphylaxis,asthma,atopic dermatitisandhay fever
Neutrophils
Neutrophils(also known asneutrocytes) are the most abundant type ofgranulocytesand the most abundant (60% to 70%)[citation needed]type ofwhite blood cellsin mostmammals. They form an essential part of theinnate immune system.
Functions
Chemotaxis – Neutrophils can detect the chemical gradients of cytokines to migrate to infected tissues
Anti-microbial function – 3 methods: phagocytosis, degranulation (causing apoptosis) and NETs
Phagocytosis – After opsonisation, neutrophils form a phagosome within which they secrete ROS, formation of super oxides and hydrolytic enzymes.
Degranulation – Release of already formed and secondarily generated chemicals which are used to break down bacteria
Neutrophil extracellular traps (NETs) – Formation of a web of fibers composed of chromatin and serine proteases that trap and kill extracellular microbes, also have potential to prevent spread of pathogens.
Eosinophils
Eosinophils are a variety ofwhite blood cellsand one of theimmune systemcomponents responsible for combating multicellularparasitesand certaininfectionsinvertebrates.[2]Along withmast cellsandbasophils, they also control mechanisms associated withallergyandasthma i.e. Type 1 hypersensitivity reactions.
Following activation by an immune stimulus, eosinophils degranulate to release an array of cytotoxic granule cationic proteins that are capable of inducing tissue damage and dysfunction.[23]These include:
major basic protein(MBP) – activates mast cells
eosinophil cationic protein(ECP)
eosinophil peroxidase(EPX)
eosinophil-derived neurotoxin(EDN)
Monocytes
Monocytesare a type ofleukocyte, orwhite blood cell. They are the largest type of leukocyte and candifferentiateintomacrophagesandmyeloidlineagedendritic cells.
Macrophages
Macrophages(Greek:big eaters) are a type ofwhite blood cellof theimmune system, that engulfs and digests cellular debris, foreign substances,microbes, cancer cells, and anything else that does not have the type of proteins specific to healthy body cells on its surface[3]in a process calledphagocytosis.
They take various forms (with various names) throughout the body (e.g.,histiocytes,Kupffer cells,alveolar macrophages,microglia, and others), but all are part of themononuclear phagocyte system. Besides phagocytosis, they play a critical role in nonspecific defense (innate immunity) and also help initiate specific defense mechanisms (adaptive immunity) by recruiting other immune cells such aslymphocytes. For example, they are important asantigen presenterstoT cells.
Dendritic Cells
Dendritic cells(DCs) areantigen-presenting cells(also known asaccessory cells) of themammalianimmune system. Their main function is to processantigenmaterial andpresentit on the cell surface to theT cellsof the immune system. They act as messengers between theinnateand theadaptive immune systems.
Dendritic cells are present in those tissues that are in contact with the external environment, such as theskin(where there is a specialized dendritic cell type called theLangerhans cell) and the inner lining of thenose,lungs,stomachandintestines. They can also be found in an immature state in theblood. Once activated, they migrate to thelymph nodeswhere they interact withT cellsandB cellsto initiate and shape the adaptive immune response.
Natural Killer Cells
Natural killer cells, also known asNK cellsorlarge granular lymphocytes (LGL), are a type ofcytotoxiclymphocytecritical to theinnate immune system. The role NK cells play is analogous to that ofcytotoxic T cellsin the vertebrateadaptive immune response. NK cells provide rapid responses tovirus-infected cells, acting at around 3 days afterinfection, and respond totumorformation.
T Lymphocytes
AT cellis a type oflymphocytewhich develops in thethymusgland (hence the name) and plays a central role in theimmune response. T cells can be distinguished from other lymphocytes by the presence of aT-cell receptoron thecell surface.
Helper CD4+ T Cells
T helper cells(THcells) assist other lymphocytes, including maturation ofB cellsintoplasma cellsandmemory B cells, and activation ofcytotoxic T cellsandmacrophages.
Cytotoxic CD8+ T Cells
Cytotoxic T cells(TCcells, CTLs, T-killer cells, killer T cells) destroy virus-infected cells and tumor cells, and are also implicated intransplantrejection.
CD8+ T cells also produce the key cytokines IL-2 and IFNγ, which influence the effector functions of other cells, in particular macrophages and NK cells.
Memory T Cells
The single unifying theme for allmemory T cellsubtypes is that they are long-lived and can quickly expand to large numbers of effector T cells upon re-exposure to their cognate antigen. By this mechanism they provide the immune system with “memory” against previously encountered pathogens. Memory T cells may be either CD4+or CD8
B Lymphocytes
B cells, also known asB lymphocytes, are a type ofwhite blood cellof the smalllymphocytesubtype.[1]They function in thehumoral immunitycomponent of theadaptive immune systembysecretingantibodies.[1]Additionally, B cellspresent antigen(they are also classified as professionalantigen-presenting cells (APCs)) and secretecytokines
Plasma Cell
Plasma cells, also calledplasma B cells, arewhite blood cellsthat originate in thebone marrowand secrete large quantities of proteins calledantibodiesin response to being presented specific substances calledantigens.
Plasma cells can only produce a single kind of antibody in a single class of immunoglobulin. In other words, every B cell is specific to a single antigen, but each cell can produce several thousand matching antibodies per second.[11]This prolific production of antibodies is an integral part of thehumoral immune response.
