University:
York University
Course:
SC/BIOL 3120 | Immunobiology
Academic year:

2023
Views:

268

Pages:

2
Author:

Niklas

T-cell Trafficking, Activation, and Helper Subset Differentiation Lymphocyte Circulation and Arrival & 2 Lymphoid Organ Lymphocyte Circulation: B-cells and T-cells originate in the bone marrow B-cells mature in bone marrow T-cells mature in thymus mature but naïve because it hasn't encountered antigen circulate around blood, lymph, barrier organs lymphocytes travel through the lymph drain into lymph nodes stay in lymph node for a little while and then moves on this is where T-cell activation 1) antigen travel to the lymph node antigen enters the body antigen can flow into the lymph node by itself via draining lymph antigen can travel to the lymph node via antigen presenting cell (dendritic cell) dendritic cells take up antigens in the skin and then move to enter a draining lymphatic vessel dendritic cells bearing antigen enter the draining lymph node, where they settle in the T-cell areas 2) lymphocytes travel to the lymph node Naïve T-cells enter a draining lymph node by two routes in the blood in the afferent lymph coming from an upstream lymph node 2 lymphoid organs: lymph nodes and spleen where lymphocytes come into contact with antigen Anatomy of Lymph Node: Follicle (B-cell zone) Paracortex (T-cell zone) Incoming (afferent) lymphatics Blood vessels Lymphocytes, APCs Outgoing (efferent) lymphatics Subcapsular sinus Cortex High endothelial venule (HEV) How does T-cell enter? Circulates through bloodstream/lymphatics arrives through high endothelial venules (HEV) migrates to the paracortex (T-cell zone) How does the antigen/APC (DC) arrive? antigen is processed and presented by the DC DC's arrive via afferent lymphatic vessels Lymphocyte Trafficking: Endothelial Cell Rolling Adhesion Diapedesis Helper T-cells (CD4+) lines the walls of vessels (blood/lymphatic) inflammation causes neutrophils/monocytes WBC move to site of injury T-cell makes its way to 2' lymphoid tissue Endothelial Cell Selectins Integrins and lg super family members Chemokines Selectins are responsible for mediating step #1 Integrins/lg super family members are responsible for mediating steps #2,3,4 Chemokines are responsible for mediating all steps (1,2,3,4)