Tag: diseases and immunity

An antibody or immunoglobulin is a  proteinaceous compound produced mainly by differentiated plasma cells i.e., B lymphocytes. It is used by the immune system to identify and neutralize pathogens such as bacteria and viruses. Thus, the correct answer is option B.

• Antibodies are the Y-shaped proteinaceous compound. Each is made up of 2 heavy chains and 2 light chains. 
• An antibody is made up of a variable region and a constant region, and the region that changes to various structures depending on differences in antigens is called the variable region, and the region that has a constant structure is called the constant region.
  
  Hence, option A is correct.

The encounter of B cell with a specific antigen activates its clonal expansion which in turn gives rise to plasma cell and memory cells.  Memory cells are the B cells (antibodies) responsible for long-term immunity and confirm the previous encounter of a person with the specific virus. Antigens are foreign substances that induce the immune system to produce antibodies. Disease-causing organisms are called as pathogens. Natural killer cells and macrophages are components of immune system. So, the correct answer is option D.

An antibody is a protein which is produced in response to the antigen by the plasma cells. Antibodies are $\gamma$-globulin proteins that have sugar groups attached to amino acid chains. They can be classified as glycoproteins. These are y-shaped. So, the correct answer is option B.

Plasma cells, also known as plasma B cells or plasmocytes are white blood cells that secrete large volumes of antibodies. They are transported by the blood plasma and the lymphatic system. Plasma cells are originated in the bone marrow, B cells differentiate into plasma cells that produce antibody molecules. Once released into the blood and lymph, these antibody molecules bind to the target antigen (foreign substance) 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. 
• IgM can bind to complement component and activate the classical pathway, leading to opsonization of antigens and cytolysis (lysis of foreign cells).
  
• IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. 
• Coating of IgG on pathogen surfaces (known as opsonization) allows their recognition and ingestion by phagocytic immune cells leading to the lysis of foreign cells.
  

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 by secreting antibodies. B-cells bind to an antigen, receive help from a cognate helper T cell and differentiate into a plasma cell that secretes large amounts of antibodies.

During an active immune response, the body can produce a massive number of antibodies to combat pathogens. The estimate of 20 trillion is generally cited in immunological literature regarding the total number of antibody molecules produced daily.

An antibody is produced by plasma cell. This plasma cell /plasma B cells/effector B cell 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.