B cells

Definition

B cells are a type of white blood cell that plays a crucial role in the adaptive immune response by producing antibodies. They originate from bone marrow and are essential for recognizing specific antigens, leading to the activation of other immune cells and the formation of memory cells, which helps the body remember past infections.

5 Must Know Facts For Your Next Test

1. B cells develop in the bone marrow and migrate to lymphoid organs where they encounter antigens.
2. When activated, B cells undergo clonal expansion, producing many identical copies that can secrete antibodies.
3. B cell activation requires help from T helper cells, which release cytokines that promote B cell proliferation and differentiation.
4. Humoral immunity, which is mediated by B cells, is crucial for defense against extracellular pathogens such as bacteria and viruses.
5. Dysfunction of B cells can lead to immunological disorders, including autoimmune diseases where the immune system mistakenly targets the body's own tissues.

Review Questions

• How do B cells contribute to the adaptive immune response and what role do they play in antibody production?
  • B cells are vital in the adaptive immune response as they are responsible for producing antibodies that target specific antigens. Upon encountering an antigen, B cells become activated, often with assistance from T helper cells, and then undergo clonal expansion to produce a large number of identical B cells. Some of these will differentiate into plasma cells that secrete antibodies, while others will form memory B cells to provide long-term immunity.
• Discuss the interaction between B cells and T helper cells during the activation process of B cells.
  • The interaction between B cells and T helper cells is critical for effective activation of B cells. When a B cell binds its specific antigen through its receptor, it internalizes the antigen and presents it on its surface via Major Histocompatibility Complex (MHC) class II molecules. T helper cells recognize this complex through their T cell receptors, leading to activation and secretion of cytokines that promote further B cell proliferation and differentiation into antibody-secreting plasma cells.
• Evaluate the implications of dysfunctional B cell activity on overall health and how it relates to autoimmune diseases.
  • Dysfunctional B cell activity can have significant health implications, particularly in relation to autoimmune diseases. In such conditions, B cells may produce antibodies against self-antigens, leading to tissue damage and inflammation. This misdirected immune response can result in various disorders, such as rheumatoid arthritis or lupus. Understanding the mechanisms behind this dysfunction can aid in developing targeted therapies to regulate B cell activity and restore normal immune function.

Related terms

Antibodies: Proteins produced by B cells that specifically bind to antigens, neutralizing pathogens or marking them for destruction by other immune cells.

Plasma Cells: A differentiated form of B cells that produces large quantities of antibodies in response to an infection.

Memory B Cells: Long-lived B cells that remain in the body after an infection has been cleared, providing rapid and effective responses to future infections by the same pathogen.