Immuno lec 4 lymphocytes pt2 Flashcards
Why are lymphocytes mostly found densely packed in specific tissues?
To increase chance of APC presentation to other lymphocytes.
To increase
What is the difference between primary and secondary lymphoid organs?
Primary or central lymphoid organs is where lymphocytes first express antigen receptors and fully mature.
Secondary lymphoid organs are the places where lymphocytes respond to foreign antigens.
What is hematopoiesis?
generation of all types of blood cells.
Where does hematopoiesis take place?
In all the skeleton in birth but becomes limited to the marrow of flat bones.
Where do T cells recognize self-antigens?
Thymic medullary epithelial cells.
T cells start at the cortex of the thymus and migrate to the medulla.
What is DiGeorge syndrome?
A syndrome where T cell count is decreased due to a gene mutation required for the thymus to grow.
How do antigens, cells, and inflammatory mediators move from the tissue to lymph nodes?
They enter into the lymphatic system when tissue fluid is absorbed.
What are lymph nodes?
Secondary lymphoid organs that are encapsulated and vascularized. Contain follicles containing B cells around follicular dendritic cells. T cells are found near the cortex (parafollicular cortex)
How are B and T cells separated into different compartments in lymph nodes and what is its importance?
They respond to different chemokines present in each part of the lymph node, this ensures that each lymphocyte is near the appropriate APCs (T with DC) (B with FDC)
How are heavy and light antigens delivered differently to B cells in the lymph node?
Heavy antigens such as viruses are collected by sinus macrophages (around the lymph node) and delivered to cortical B cells.
Light and soluble antigens are transported to resident dendritic cells and then display the antigens to T cells INITIALLY, long-term response requires delivery via tissue dendritic cells
What is the function of the spleen?
Get rid of aging and damaged blood cells and particles and initiate the adaptive immune response to blood-borne antigens.
What are the divisions of the spleen?
Red pulp, made mainly of blood filled vascular sinusoids.
White pulp full of lymphocytes.
How is blood filtered in the spleen?
macrophages in the red pulp remove microbes and damaged cells.
Who are the people that are at risk of encapsulated bacteria infections?
people lacking a spleen.
What is the function of the white pulp in the spleen?
Promotes immunity against blood-borne antigens.
