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Each antibody binds to a specific antigen in a highly specific interaction analogous to a lock and key.. An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that cause disease.
Plasmablasts secrete more antibodies than B cells, but less than plasma cells. [12] They divide rapidly and are still capable of internalizing antigens and presenting them to T cells. [12] A cell may stay in this state for several days, and then either die or irrevocably differentiate into a mature, fully differentiated plasma cell. [12]
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. [1] They function in the humoral immunity component of the adaptive immune system. [1] B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. [2]
Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses, bacteria, and fungi, IgG protects the body from infection. [citation needed]
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
Complementarity-determining regions (CDRs) are polypeptide segments of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively. CDRs are where these molecules bind to their specific antigen and their structure/sequence determines the binding activity of the respective antibody.
These B cells produce IgM antibodies to help clear infection. [20] T-bet memory B cells. T-bet B cells are a subset that have been found to express the transcription factor T-bet. T-bet is associated with class switching. T-bet B cells are also thought to be important in immune responses against intracellular bacterial and viral infections. [21]
Here, a pathogen spends most of its life-cycle inside host cells, where it is shielded from direct contact with immune cells, antibodies and complement. Some examples of intracellular pathogens include viruses, the food poisoning bacterium Salmonella and the eukaryotic parasites that cause malaria ( Plasmodium spp. ) and leishmaniasis ...