Tag: bio-chemistry

An antibody, also known as an immunoglobulin is a large, Y-shaped protein which is produced mainly by plasma cells and it is used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses. Antibodies are secreted by B lymphocytes of the adaptive immune system, mostly by differentiated B cells called plasma cells. 

Antibodies are produced by specialized white blood cells called B lymphocytes/ B-cells. When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone. The mature B cells,called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system. Hence antibodies are secreted from lymphocytes.

Immunoglobulin A is an antibody that plays a crucial role in the immune function of mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other types of antibody combined. It is the main immunoglobulin found in mucous secretions, including tears, saliva, sweat, colostrum and secretions from the genitourinary tract, gastrointestinal tract, prostate and respiratory epithelium. It is also found in small amounts in the blood. Hence it provides immunity to the digestive tract as it is made up of a mucous membrane.

Immunoglobulin E (IgE) is a type of antibody that has only been found in mammals. IgE is synthesised by plasma cells. It plays an essential role in type I hypersensitivity, which manifests in various allergic diseases, such as allergic asthma, rhinitis etc. It also plays a pivotal role in responses to allergens, such as anaphylactic drugs, bee stings, and antigen preparations used in desensitization immunotherapy.

An antibody is produced by plasma cell. The B-Lymphocytes are white blood cells that secrete large volumes of antibodies. Plasma cell originates in the bone marrow. B cell differentiate into a plasma cell that produces antibody molecules. These are transported by the blood plasma and the lymphatic system. Once these are released into the blood and lymph, these antibody molecules bind to the target antigen and initiate its neutralization or destruction.

Immunoglobulin M (IgM) is one of several forms of the antibody that are produced by vertebrates. IgM is the largest antibody and it is the first antibody to appear in the response to initial exposure to an antigen. On the basis of its sedimentation velocity and appearance in electron micrographs, it was inferred that IgM is mostly a pentamer i.e., a polymer composed of five monomers.

• In response to an allergy, IgE is secreted and circulates in the blood and binds to an IgE-specific receptor on the surface of other kinds of immune cells called mast cells and basophils, which are both involved in the acute inflammatory response.
•  The IgE-coated cells, at this stage, are sensitized to the allergen. 
• Hence, IgG and mast cells are involved in an allergic reaction.
• So, the correct answer is 'IgG and mast cells'.

• Immunoglobulin A (IgA) is an antibody that plays a crucial role in the immune function of mucous membranes.
• Colostrum is a milky fluid that comes from the breasts of humans, cows, and other mammals the first few days after giving birth before true milk appears.
• Immunoglobulin abundant in colostrum is IgA in the form of secretory IgA or sIgA. Much of these are produced by plasma cells in the mammary tissue.
• So, the correct answer is 'IgA'.

Immunoglobulin M (IgM) is one of several forms of the antibody that are produced by vertebrates. IgM is the largest antibody and it is the first antibody to appear in the response to initial exposure to an antigen in the blood. IgM antibodies appear early in the course of an infection and usually reappear to a lesser extent after further exposure to the same antigen. IgM antibodies do not pass across the human placenta.

The thymus gland, despite containing glandular tissue and producing several hormones, is much more closely associated with the immune system than with the endocrine system. The thymus serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. T cells defend the body from potentially deadly pathogens such as bacteria, viruses, and fungi. The function of the thymus is to receive immature T cells that are produced in the red bone marrow and train them into functional, mature T cells that attack only foreign cells. T cells first reside within the cortex of the thymus where they come in contact with epithelial cells presenting various antigens. The immature T cells that respond to the antigens corresponding to foreign cells are selected to survive, mature, and migrate to the medulla while the rest die via apoptosis and are cleaned up by macrophages.