Card Set Information
SFOS Lymphoid Organs Immune Response
What cells have CD4?
CD4 - Helper T Cells
CD8 - Cytotoxic Cells
What cells are effected by Natural Killer Cells and gd T lymphocytes?
By what mechanism?
Tumor cells or virally-transformed cells
Release perforins and fragmentins or cytokines
What defines an Antigen Presenting Cell?
Must express MHC Class II
Langerhans' cells in epidermis
Reticular dendritic cells of spleen/lymph nodes
Define Antigen processing
Intracellular conversion of native proteins into peptides and loading onto MHC molecules
What presents endogenous antigens?
Where does antigen processing take place?
MHC Class I
Virally infected cells, tumor antigens
Occurs in cytoplasm of infected/tumor cells
What presents exogenous antigens?
MHC Class II
What are the two types of cytokines and their associated responses?
Pro-inflammatory - cellular immune response
Anti-inflammatory - humoral immune response
Describe the mechanism of interferons
Produced by virally infected cells
Activate natural killer cells
What are lymph nodules?
Unencapsulated lymphoid tissue
MALT, GALT, BALT
What are the structural and functional differences between primary and secondary nodules (follicles)?
Secondary nodules have pale Germinal Center, contains B-lymphoblasts (active proliferation)
Primary nodules - densely packed small lymphocytes
What are Peyer's pathes and their associated structures?
Unencapsulated lymph nodules in ileum
Contain high endothelial venules (blood vessels)
M (microfold) cells - endocytose antigens
1. Are tonsils encapsulated?
2. Describe the crypt structure of different tonsils
1. Yes - dense connective tissue capsule
2. Palatine tonsil - 10 to 20 deep crypts
Pharyngeal tonsil (adenoid) - no crypts
Lingual tonsil - single crypt
What are the function of lymph nodes?
Reaction to antigens presented to B lymphocytes by macrophages and follicular dentritic cells
Extensions of the capsule into the lymph tissue
What are the structural framework cells/fibers of lymph nodes?
Describe the path of lymph in a lymph node
Afferent lymphatic capillaries -->
Subcapsular sinuses -->
Trabecular sinuses -->
Medullary sinuses -->
Efferent lymphatic vessel
Where do B cells differentiate?
Interfollicular spaces in the cortex of lymph nodes
Where are T Cells located in lymph nodes?
Deep dense paracortical area
Describe the splenic features:
1. White pulp
2. Periperal white pulp
3. Red pulp
4. Marginal zone
1. T-lymph in Periarteriolar lymphatic sheaths (PALS), B-lymph in nodules
2. B-cell area in white pulp
3. Splenic cords and sinusoids
4. Area between white and red pulp containing APCs
Does the thymus have germinal centers or nodules?
Cortex is T Cells
What tissue forms the thymus?
Endoderm - epithelial reticular tissue
What is thymic education and where does it take place?
Maturation of lymphatic stem cells
What prevents foreign antigens from reaching the thymic cortex?
Blood-thymic barrier (type I cells)
What are the types of epithelioreticular cells?
Type I - blood thymic barrier
Type II - express MHC I/II
Type III - express MHC I/II, cortex/medulla barrier
Type IV - cortex/medulla barrier
Type V - ?
Type VI - for Hassel's corpuscles (produce thymic hormones)