Tag: diseases and immunity

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.

Antibodies are secreted by cells of the adaptive immune system; B cells, which are formed by the differentiation of the plasma cells. B lymphocytes have antibodies attached to them. Once they detect an antigen, they transform into plasma cells and secrete antibodies until the immune response is over. 

If the identical antibodies are produced by the single clone of cells such antibodies are called as monoclonal antibodies. They are clones or single type but they are target specific. Each monoclonal antibody recognizes one particular protein (antigen). They work in different ways depending on the protein they are targeting. Thus, the correct answer is option B.