Immune System Flashcards
Types of immunity
Innate and adaptive
Adaptive immunity
Humoral - B cells and B lymphocytes
Cell based - T cells and T lymphocytes; APC’s with MHC II
Thymus
Primary lymphoid organs
Trains incompetent T cells; site of development and maturation
T cells are tested for:
-Ability to interact with MHC I molecules (self) = positive selection
-Ability to recognize epitopes of self-antigens (anti-self) = negative selection
Adipose tissue replaces thymic tissue with age
Thymic cortex
Proliferation of T lymphocytes
Site of positive selection for “self” MHC I molecules
Thymic medulla
Negative selection against self-antigens (final step to generate immunocompetent T cells)
Contains Hassall’s corpuscles
Bone marrow
Primary lymphoid tissue
Site of B cell development and maturation
Cloacal bursa
Primary lymphoid organ for B-cell production in birds
High endothelial venules
Found in all secondary venules found in all secondary lymphoid structures except for spleen
Peyer’s patch
Lymphoid follicles in ileum (part of GALT)
Contains M-cells - APC’s that capture antigens and present them to lymphocytes
Lymph nodes
Dense encapsulated lymphoid tissue
Lymph nodules
Primary lymphoid nodule - B cell foci; lack germinal centers
Secondary lymphoid nodule - Germinal center formation
Porcine lymph node
Reverse histologic pattern with the same function
Central lymph nodules
Peripheral and internal medullary cords
Hemal nodes
Found in ruminants
Found at vertebral column and jugular furrow
Act as miniature spleens - not necessary for life
Spleen
Contains red pulp (mechanical filtration of RBC’s) and white pulp (immune response)
Site of EMH
Stores RBC’s and is capable of splenic contraction to increase RBC’s in circulation
PALS
Periarterial lymphoid sheath
Dense sheath of T lymphocytes and some APC’s
Blood borne antigens presented to T cells by APC’s
