20 Questions
Where are B cells concentrated in lymph nodes?
Follicles located around the periphery
What is the role of germinal centers?
Production of highly effective antibodies
Where are T lymphocytes concentrated in the spleen?
Periarteriolar lymphoid sheaths surrounding small arterioles
What attracts and retains B cells in the follicles?
Chemokines
What is the physiologic function of the immune system?
To eliminate infectious microbes and cancers
Where are microbial antigens concentrated to increase the likelihood of T cells finding their antigens?
Secondary lymphoid organs, particularly lymph nodes
Which cells remain in lymphoid organs and the bone marrow to secrete antibodies that find and eliminate microbes?
Plasma cells
What is the function of cytotoxic T lymphocytes (CTLs)?
Kill infected cells harboring microbes in the cytoplasm
What do B lymphocytes produce?
Antibodies
Which chemokine is secreted by follicular dendritic cells (FDCs) to attract naive B cells into lymphoid organ follicles?
CXCL13
Which chemokine receptor is expressed by naive T lymphocytes recognizing chemokines in the paracortex of lymph nodes and periarteriolar lymphoid sheaths of the spleen?
CCR7
Where do antigen-activated B and T cells migrate towards each other to interact?
Edge of follicles
What ensures cells interact and communicate after antigen exposure in lymphoid organs?
Lymphoid organ structure
Where are B cells primarily located in a histological section of a lymph node?
Follicles
Where do effector T cells exit to reach distant infection sites?
Lymph nodes and spleen
What is the primary function of plasma cells in mucosal organs?
Secreting antibodies combating ingested and inhaled microbes in mucosal organs' lumen
Where do naive T lymphocytes primarily migrate from the blood into the T cell zones of lymph nodes?
High endothelial venules
How do naive T cells primarily enter lymph nodes?
Binding to adhesion molecules and chemokines on high endothelial venules
How do naive T cells primarily remain in the paracortex of lymph nodes?
Chemokine attraction
What is the primary function of effector T cells at sites of infection?
Locating and eliminating microbes
Study Notes
Lymphocyte Migration and Interaction in Lymphoid Organs
- FDCs in follicles secrete a chemokine, CXCL13, recognized by naive B cells expressing the receptor CXCR5, which attracts B cells from the blood into lymphoid organ follicles.
- Naive T lymphocytes express CCR7, recognizing chemokines in the paracortex of lymph nodes and periarteriolar lymphoid sheaths of the spleen, segregating T cells in these regions.
- Upon antigen activation, lymphocytes alter their chemokine receptor expression, allowing antigen-activated B and T cells to migrate towards each other and interact at the edge of follicles.
- Lymphoid organ structure ensures cells interact and communicate after antigen exposure, exemplifying how cells recognizing an antigen interact and communicate when necessary.
- Histological section of a lymph node shows B cells in follicles and T cells in the parafollicular cortex, highlighting the anatomic segregation of T and B cells.
- Effector T cells exit lymph nodes and spleen, entering the circulation to reach distant infection sites, while some remain in lymphoid organs to help B cells produce antibodies.
- Naive lymphocytes recirculate between blood and secondary lymphoid organs, where they may be activated by antigens to become effector cells, and effector lymphocytes migrate to sites of infection.
- Effector T cells migrate to sites of infection to locate and eliminate microbes, while B cell–derived plasma cells secrete antibodies that circulate in the blood.
- Plasma cells in mucosal organs secrete antibodies combatting ingested and inhaled microbes in the lumen of these organs.
- Naive T lymphocytes migrate from the blood through high endothelial venules into the T cell zones of lymph nodes, where they are activated by antigens.
- T lymphocytes migrate into lymph nodes by binding to adhesion molecules and chemokines on the endothelial lining of high endothelial venules, remaining in the paracortex due to chemokine attraction.
- Naive T cells move around rapidly along specialized connective tissue fibers in the lymph node paracortex, scanning the surfaces of dendritic cells for antigens, forming stable conjugates upon recognition.
Test your knowledge on the migration and interaction of lymphocytes in lymphoid organs. Learn about the chemokines, receptors, and structural segregation that facilitate lymphocyte movement and communication.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
