A&P Immune system- White blood cells

Memory T-cells

A subset of antigen-specific T cells that persist long-term after an infection has resolved. They quickly expand to large numbers of effector T cells upon re-exposure to their cognate antigen, thus providing the immune system with "memory" against past infections.

Phagocyte

A type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles.

Natural killer cells

Able to kill cells of the body that do not display MHC signals. Decreased expression of MHC class I and up-regulation of MIC-A can happen when cells are infected by a virus or become cancerous.

Macrophages

After a monocyte leaves the bloodstream they become this. This Engulfs and digests cellular debris, foreign substances, microbes, and cancer.

White blood cells

Also called leukocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All leukocytes are produced from a hematopoietic in the bone marrow. Five different and diverse types of leukocytes exist

Heparin

An anticoagulant that inhibits blood clotting and promotes the movement of white blood cells into an area. They can also release chemical signals that attract eosinophils and neutrophils to an infection site.

Lymphocyte

Are distinguished by having a deeply staining nucleus that may be eccentric in location, and a relatively small amount of cytoplasm. There are different types of lymphocytes.

Leukocytes

Are white blood cells and vise versa.

Helper T-cells

Assist other white blood cells in maturation of B cells into plasma cells and memory B cells, and activation of cytotoxic T cells and macrophages. They express the CD4 glycoprotein on their surfaces. They become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells. They then divide rapidly and secrete small proteins called cytokines that regulate or assist in the active immune response.

Basophil

Basophils are chiefly responsible for allergic and antigen response by causing vasodilation. They are the rarest of the white blood cells. They can be recognized by several coarse, dark violet granules, giving them a blue hue. The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules that hide it.

(natural) Killer T-cells

Bridge the adaptive immune system with the innate immune system. These cells recognize the glycolipid antigen presented by a molecule called CD1d. Once activated, these cells can cause cytokine production and release of cytolytic/cell killing molecules. They are also able to recognize and eliminate some tumor cells and cells infected with herpes viruses.

Hydrolitic enzymes

Capable of breaking down virtually all kinds of biomolecules, including proteins, nucleic acids, carbohydrates, lipids, and cellular debris.

Lysosomes

Capable of breaking down virtually all kinds of biomolecules, including proteins, nucleic acids, carbohydrates, lipids, and cellular debris. Thus they act as waste disposal system of the cell by digesting unwanted materials in the cytoplasm.

Cytotoxic T-cells

Destroy virus-infected cells and tumor cells, and are also implicated in transplant rejection. They express the CD8 glycoprotein at their surfaces. These cells recognize their targets by binding to antigen associated with MHC class I molecules, which are present on the surface of all nucleated cells.

B-cells

Distinguished by the presence of a protein surfaceknown as a B cell receptor (BCR). This allows a B cell to bind to a specific antigen. Immature B cells are formed in the bone marrow. The principal functions of B cells are to make antibodies against antigens and to develop into memory B cells after antigen interaction. B cells also release cytokines.

Plasma B cells

Large B cells that have been exposed to antigen and produce large amounts of antibodies, which bond to them and make them easier targets for phagocytes and the complement system. An antibody factory, lots of rough endoplasmic reticulums for synthesizing the antibody. in the cell's cytoplasm. After the antigen-infected cell dies, the plasma B-cell that bonded to it also dies.

T cells

Plays a central role in cell-mediated immunity. They are distinguished by the presence of a T-cell receptor (TCR) on the cell surface. They are called T cells because they mature in the thymus (some mature in the tonsils). There are different types of T-cells.

Memory B-cells

Specific to the antigen encountered during the primary immune response. These cells are able to live for a long time, and can respond quickly following a second exposure to the same antigen.

Types of helper T-cells

TH1, TH2, TH3, TH17, Th9, or TFH, which secrete different cytokines to facilitate different types of immune responses.

Vasodilation

The widening of blood vessels

Regulatory T-cells/ suppressor t-cells

Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress autoreactive T cells that escaped the process of negative selection in the thymus. Regulatory T cells can develop either during normal development in the thymus or can be induced peripherally and are called peripherally derived Treg cells. These two subsets were previously called "naturally occurring", and "adaptive" or "induced".

Neutrophil

They defend against bacterial or fungal infection. Their activity and death in large numbers forms pus. They have a nucleus with of three to five lobes connected by slender strands.The cytoplasm may look transparent because of fine granules that are pale lilac when stained. These cells are not able to renew their lysosomes and die after having phagocytosed a few pathogens. The most common cell for inflammation.

Monocyte

They present pieces of pathogens to T cells so that the pathogens may be recognized again and killed. Monocytes eventually leave the bloodstream and become tissue macrophages. Monocytes are able to replace their lysosomal contents and are thought to have a much longer active life. They have the kidney shaped nucleus and are typically agranulated. They also possess abundant cytoplasm.

Eosinophil

They primarily deal with parasitic infections and allergic reactions. Rare in the blood, but numerous in the mucous membranes of the respiratory, digestive, and lower urinary tracts. They secrete chemicals that destroy large parasites that are too big for any one white blood cell to phagocytize. Their nucleus is bi-lobed andconnected by a thin strand. The cytoplasm is full of granules that are pink-orange color with eosin staining.

Cytokine

Used for signaling immune regulatory functions.

Histamine

Widening blood vessels and increase the flow of blood to an injured tissue.