[03] Lymphocyte Development and Activation Flashcards
What are the two main types of lymphocytes?
- B lymphocytes (B cells)
- T lymphocytes (T cells)
Where do lymphocytes originate from?
They originate from stem cells in the bone marrow
Where do B cells mature?
B cells mature in the bone marrow
Where do T cells mature?
T cells mature in the thymus
What is the role of B cells in immunity?
They produce antibodies that are used to attack invading bacteria, viruses, and toxins
What is the role of T cells in immunity?
They are involved in cell-mediated immunity
What does it mean when a B cell or T cell is “activated”?
An activated lymphocyte has recognized its specific antigen and responds by proliferating and differentiating
What triggers B cell activation?
Interaction with an antigen and assistance from a helper T cell
What are the outcomes of B cell activation?
- Plasma cells that produce antibodies
- Memory B cells that are ready for future exposure to the antigen
What triggers T cell activation?
Interaction with an antigen presented on the surface of an antigen-presenting cell (APC)
What are the outcomes of T cell activation?
- Cytotoxic T cells that destroy infected cells
- Helper T cells that assist in B cell activation
- Memory T cells that are ready for future exposure to the antigen
What are antigen-presenting cells (APCs)?
Cells that process and present antigens to T cells
What is the role of helper T cells in lymphocyte activation?
They enhance the response of other immune cells like B cells and cytotoxic T cells
What is the role of cytotoxic T cells in lymphocyte activation?
They kill infected cells
What is the role of memory B cells and memory T cells?
They provide long-term immunity and rapid response upon re-exposure to the same antigen
What is clonal expansion?
The rapid multiplication of B or T cell clones after activation by an antigen
What is clonal selection?
The process by which a B or T cell is activated by its specific antigen, leading to the production of more cells that recognize the same antigen
What is immune tolerance?
The ability of the immune system to avoid responding to its own cells and proteins
How does the immune system achieve tolerance?
Through mechanisms during lymphocyte development that lead to deletion or inactivation of self-reactive cells
What is the function of regulatory T cells in immune tolerance?
They suppress the immune response to prevent an overreaction
