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Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response, making it one of the mechanisms of antigenic escape. It is related to phase variation. Antigenic variation not only ...
Acting as both an antigen and adhesion protein, it is thought to play a key role in the high level of virulence associated with P. falciparum. It was discovered in 1984 when it was reported that infected RBCs had unusually large-sized cell membrane proteins, and these proteins had antibody-binding (antigenic) properties. An elusive protein, its ...
IgM is first expressed as a monomer on the surface of immature B cells. Upon antigenic stimulation, IgM+ B cells secrete pentameric IgM antibody formed by five Ig monomers which are linked via disulfide bonds. The pentamer also contains a polypeptide J-chain, which links two of the monomers and facilitates secretion at mucosal surfaces.
The classical pathway is distinct from the other complement pathways in its unique activation triggers and cascade sequence. Activation of the complement pathway through the classical, lectin or alternative complement pathway is followed by a cascade of reactions eventually leading to the membrane attack complex.
Mechanism of class-switch recombination that allows isotype switching in activated B cells. Immunoglobulin class switching, also known as isotype switching, isotypic commutation or class-switch recombination (CSR), is a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG. [1]
Antigen processing and presentation in MHC-I pathway Cytotoxic T cells (also known as T c , killer T cell, or cytotoxic T-lymphocyte (CTL)) express CD8 co-receptors and are a population of T cells that are specialized for inducing programmed cell death of other cells.
Memory T cells also make use of this pathway and have higher levels of Lck expressed and the function of Csk is inhibited in these cells. [ 14 ] The binding of the antigen-MHC to the TCR complex and CD4 may also help the APC and the T h cell adhere during T h cell activation, but the integrin protein LFA-1 on the T cell and ICAM on the APC are ...
The alternative pathway is a type of cascade reaction of the complement system and is a component of the innate immune system, a natural defense against infections. The alternative pathway is one of three complement pathways that opsonize and kill pathogens. The pathway is triggered when the C3b protein directly binds a microbe. It can also be ...