memory B cell differentiation

Definition

Target type: biologicalprocess

The process in which a B cell acquires the specialized features of a memory B cell. Memory B cells are cells that can respond rapidly to antigen re-exposure by production of high-affinity antibody. [GOC:jal, ISBN:0781735149]

Memory B cell differentiation is a complex process that involves the development of long-lived B cells that retain the ability to rapidly mount an immune response upon re-exposure to a specific antigen. This process is crucial for providing long-term immunity against pathogens.

Upon encountering an antigen, naive B cells undergo a series of activation and differentiation steps. These steps include:

1. **Antigen recognition and activation:** Naive B cells express B cell receptors (BCRs) on their surface that specifically bind to antigens. When a BCR encounters its cognate antigen, it triggers a signaling cascade that leads to the activation of the B cell.

2. **T cell-dependent activation:** Most B cell responses require the help of T helper cells (Tfh cells). Activated B cells present antigen fragments to Tfh cells, which in turn provide signals that promote B cell proliferation, differentiation, and antibody production.

3. **Germinal center formation:** Activated B cells migrate to specialized structures called germinal centers within secondary lymphoid organs, such as lymph nodes and the spleen. Germinal centers are sites of intense B cell proliferation, somatic hypermutation, and affinity maturation.

4. **Somatic hypermutation:** During germinal center reactions, B cells undergo somatic hypermutation, a process that introduces random mutations into the variable regions of their immunoglobulin genes. This process leads to the generation of B cells with diverse antibody specificities.

5. **Affinity maturation:** B cells that produce antibodies with higher affinity for the antigen are preferentially selected for survival and proliferation. This process, known as affinity maturation, ensures that the antibody response becomes increasingly specific and effective over time.

6. **Differentiation into memory B cells:** A subset of activated B cells differentiate into memory B cells, which are long-lived cells that can survive for many years. Memory B cells retain the antigen specificity of their parental B cells and are primed to rapidly mount an immune response upon re-exposure to the antigen.

7. **Plasma cell differentiation:** Another subset of activated B cells differentiate into plasma cells, which are specialized antibody-secreting cells. Plasma cells produce and secrete large quantities of antibodies into the bloodstream.

Memory B cells play a critical role in providing long-term immunity against pathogens. When an individual is re-exposed to an antigen that they have previously encountered, memory B cells can quickly recognize and bind to the antigen. This binding event triggers the rapid activation and differentiation of memory B cells into plasma cells, which then produce a high-affinity antibody response that effectively neutralizes the pathogen.'
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