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Some memory B cells can be activated without T cell help, such as certain virus-specific memory B cells, but others need T cell help. [26] Upon antigen binding, the memory B cell takes up the antigen through receptor-mediated endocytosis, degrades it, and presents it to T cells as peptide pieces in complex with MHC-II molecules on the cell ...
These T cells bind to the MHC II-antigen molecule and cause activation of the B cell. This is a type of safeguard to the system, similar to a two-factor authentication method. First, the B cells must encounter a foreign antigen and are then required to be activated by T helper cells before they differentiate into specific cells. [8]
B cells and T cells are derived from the same multipotent hematopoietic stem cells, and look identical to one another until after they are activated. B cells play a large role in the humoral immune response , whereas T cells are intimately involved in cell-mediated immune responses .
Germinal centers or germinal centres (GCs) are transiently formed structures within B cell zone (follicles) in secondary lymphoid organs – lymph nodes, ileal Peyer's patches, and the spleen [1] – where mature B cells are activated, proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation aimed at achieving higher affinity) during a normal immune response ...
Step 3: A T helper cell binds to the macrophage and becomes an activated T helper cell. Step 4: The activated T helper cell binds to a B cell in order to activate the B cell. Step 5: When the B cells are activated, some B cells turn into plasma cells and are released in the blood, while other B cells become B memory cells that quicken response ...
T cells are grouped into a series of subsets based on their function. CD4 and CD8 T cells are selected in the thymus, but undergo further differentiation in the periphery to specialized cells which have different functions. T cell subsets were initially defined by function, but also have associated gene or protein expression patterns.
Co-stimulation of the B cell by activated T cell resulting in its complete activation. Proliferation [note 4] of B cells with resultant production of soluble antibodies. Steps in production of antibodies by B cells: 1. Antigen is recognized and engulfed by B cell 2. Antigen is processed 3. Processed antigen is presented on B cell surface 4.
They present the antigen to T cells and, if there is a T cell with the appropriate T cell receptor, it will be activated. [27] B cells acquire antigen directly from the afferent lymph. If a B cell binds its cognate antigen it will be activated. Some B cells will immediately develop into antibody secreting plasma cells, and secrete IgM.