Lecture 4 Flashcards
Name the primary and secondary lymphoid tissue
primary: bone marrow and thymus
secondary: lymph nodes, spleen, bronchi associated lymphoid tissue, nasopharynx LT, skin associated LT, gut associated LT
What occurs at the secondary lymphoid organs?
antigen encounters lymphocytes
Describe the draining lymph nodes.
Draining lymph node are a site where antigen bearing dendritic cells interact with lymphoctes. They are located where lymphatic vessels converge. When activated they prolif and release effector cells lasting 4-6 days. Naive lymphocytes not activated recirculate through the secondary lymphoid tissues until they recognise antigen or die.
Describe the Cellular architecture of the lymph node
Drawing slide 5 l4
outer cortex - houses B cells organised into follicles
paracortex - T cells and dendritic cells reside
During an immune response, secondary follicles form with germinal centers of proliferating activated B cells
Medulla consists of macrophages and antibody-secreting plasma cells
describe the Transport of antigen to the lymph node for presentation to t cells
immature dendritic cells take up antigen in the peripheral tissues (macropinocytosis and receptor-mediated endocytosis)
They’re then activated through PRR detection of PAMPs, migrate via afferent lymphatics to the regional lymph nodes
Once there, they present antigen and expression co-stimulatory molecules to activate naiive t cells that enter the higher endothelial venules.
Describe the transport of antigen to the lymph node for presentation to b cells
compliment opsonised Ags (free antigen/peptide) enter the lymph node and bind to the surface of the macrophages in the subcapular sinus
macrophages maintain Ag on their surfaces allowing B cells to encounter them
Also allows Ag to be transported into the follicle to become trapped on the surface of follicular dendritic cells
Describe the structure of the follicle
primary follicles are a collection of naiive B cells
