Antigens can come from pathogens, foreign particles, or cell debris. They can be particulate, existing as solid particles. In lymph nodes, dendritic cells, follicular dendritic cells, and macrophages transfer antigens to B cells. B cell receptors recognize and process antigens, triggering B cell activation. Learn more about Professional Antigen Presenting Cells in our free Immunology course.

The lymph node's anatomy is finely tuned to process lymphatic fluid and launch immune responses. Key components include the capsule, afferent and efferent lymphatic vessels, subcapsular region, cortex with B cell follicles and T cell-rich paracortex, and the medulla. This setup aids in antigen capture, immune cell activation, and adaptive immune response generation.

Dendritic cells play a crucial role in the immune system, transitioning from immature to mature states to activate T cells. They enter lymph nodes through afferent lymphatic vessels or high endothelial vessels, using chemotaxis and adhesion molecules. Once inside, they interact with T cells to initiate adaptive immune responses. This is part of a free immunology course.