How do B cells process antigen?

How do B cells process antigen?

The presentation of antigens by B cells on MHC class II molecules is a complex process that involves several stages: first, external antigens are recognized and captured by B cells through their B cell receptor (BCR); second, the antigen is processed by degrading the antigen in internal compartments within the B cell ...

What does antigen-presenting B cells mean?

An antigen-presenting cell (APC) is an immune cell that detects, engulfs, and informs the adaptive immune response about an infection. ... Before activation and differentiation, B cells can also function as APCs. After phagocytosis by APCs, the phagocytic vesicle fuses with an intracellular lysosome forming phagolysosome.

Do B cells ingest antigens?

Most of the B cells act as "effector" or "plasma" B cells. They make large amounts of their receptor proteins and then release them into the body fluid. These "circulating B receptors" are also known as "antibodies" or "immunoglobulins". ... The result is that any foreign cells having the antigen on them are destroyed.

How is an antigen produced?

Endogenous antigens are generated within normal cells as a result of normal cell metabolism, or because of viral or intracellular bacterial infection. The fragments are then presented on the cell surface in the complex with MHC class I molecules.

What types of antigens do B cells recognize?

B-cell receptors (BCRs) are membrane-bound monomeric forms of IgD and IgM that bind specific antigen epitopes with their Fab antigen-binding regions.

Where do B cells see antigen?

Membrane-bound immunoglobulin on the B-cell surface serves as the cell's receptor for antigen, and is known as the B-cell receptor (BCR). Immunoglobulin of the same antigen specificity is secreted as antibody by terminally differentiated B cells—the plasma cells.

When do B cells act as antigen-presenting cells?

In addition to their role as secretors of antibodies, B cells function as professional antigen-presenting cells (APCs) for CD4+ T cells by expressing cell-surface major histocompatibility complex class II (MHCII) molecules with bound peptide, the ligand of the α/β T cell receptor.

How do B cells of immune system respond to antigens?

In one class of response, B cells secrete antibodies that neutralize the virus. In the other, (more...) In cell-mediated immune responses, the second class of adaptive immune response, activated T cells react directly against a foreign antigen that is presented to them on the surface of a host cell.

How does the immune system recognize antigens?

How Does the Immune System Work? When the body senses foreign substances (called antigens), the immune system works to recognize the antigens and get rid of them. B lymphocytes are triggered to make antibodies (also called immunoglobulins). These proteins lock onto specific antigens.

What are 3 types of antigens?

The three broad ways to define antigen include exogenous (foreign to the host immune system), endogenous (produced by intracellular bacteria and virus replicating inside a host cell), and autoantigens (produced by the host).

What happens when a B cell receptor connects to an antigen?

• When a B-cell receptor connects to its specific antigen, a Helper T-cell releases chemicals that tell that B-cell to divide many times. This makes an army of B-cells with the perfectly shaped B-cell receptor to connect to the invader in your body.

How are antibodies made in the B cell?

• Plasma cells make and release antibodies that connect to the same antigen as the original B-cell receptor. Plasma cells make thousands of antibodies per second, which spread throughout your body, trapping any viruses they see along the way. What do antibodies do? Antibodies trap invading viruses or bacteria in large clumps.

Where does B cell activation occur in the body?

• B cell activation occurs in the secondary lymphoid organs (SLOs), such as the spleen and lymph nodes. After B cells mature in the bone marrow, they migrate through the blood to SLOs, which receive a constant supply of antigen through circulating lymph. At the SLO, B cell activation begins when the B cell binds to an antigen via its BCR.

What happens when a B cell becomes a plasma cell?

• B-Cell. Many of these B-cells quickly turn into Plasma cells. Plasma cells make and release antibodies that connect to the same antigen as the original B-cell receptor. Plasma cells make thousands of antibodies per second, which spread throughout your body, trapping any viruses they see along the way.