Test Your Knowledge on Peripheral Lymphoid Organs and Immune Responses

Anatomy and Function of Peripheral Lymphoid Organs in Immune Responses

• Peripheral lymphoid organs include lymph nodes, spleen, and mucosal and cutaneous immune systems.
• These organs promote the development of adaptive immune responses by enabling T and B lymphocytes to locate and respond to microbes.
• The anatomic organization of peripheral lymphoid organs allows APCs to concentrate antigens and lymphocytes to locate and respond to them.
• Helper T cells interact with and help B lymphocytes in peripheral lymphoid organs, resulting in antibody production.
• Lymph nodes are encapsulated nodular aggregates of lymphoid tissues located along lymphatic channels throughout the body.
• The lymph contains a mixture of substances absorbed from epithelia and tissues, and antigens of microbes become concentrated in draining lymph nodes.
• The spleen serves the same role in immune responses to blood-borne antigens as lymph nodes in responses to lymph-borne antigens.
• Cutaneous and mucosal immune systems are specialized collections of lymphoid tissues and APCs located in and under the epithelia of the skin and gastrointestinal and respiratory tracts.
• T and B lymphocytes are segregated into different anatomic compartments in peripheral lymphoid organs.
• Chemokines attract B cells to follicles and T cells to paracortex of lymph nodes and periarteriolar lymphoid sheaths of the spleen.
• The anatomic organization of peripheral lymphoid organs ensures that cells that have recognized and responded to an antigen interact and communicate with one another only when necessary.
• Effector T cells exit the node through efferent lymphatic vessels and leave the spleen through veins, while some activated T cells remain in the lymphoid organ and help B cells to make high-affinity antibodies.