Immunology-Lymphoid System Flashcards
Primary lymphoid system
lymphoiesis ex. development of T and B lymphocytes to mature antigen-specific cells
maturation and selection of lymphocytes
not influenced by antigen challenge, don’t respond to antigen
most active in young animals, atrophy with age
supply T and B cells to secondary lymphoid system
Secondary lymphoid system
generate immune response
populated by T and B cells and macrophages
spleen, lymph nodes, tonsils, Peyer’s patches
lamina propria of GI and bronchioles
each organ in charge of particular environment
Spleen
major filtration organ of blood
responds immunologically to antigens within the blood
antibody production, hemopoiesis, storing blood, removing effete erythrocytes
made of red and white pulp
red=network of cell cords (macrophages, plasma cells, and fibroblasts) and vascular sinuses
white=discrete lymphoid aggregations surrounding an arteriole
PALS= immediately surrounding arteriole, sheath of T cells
PALS<zone of B cells and marcrophages (marginal zone)
How do lymphocytes migrate in the spleen?
enter in arterial blood> into white pulp> T cells migrate through PALS, B cells through marginal zone> into marginal sinuses> splenic sinuses>splenic vein>
if interact w/ antigen, immune response takes place in white pulp
T cells prolif in PALS, B cells in MZ
products leave spleen via marginal sinuses, some plasma cells stay in splenic cords and secrete antibody
What is the anatomy of a lymph node?
contained within fibrous capsule that extends into node as trabeculae
subcapsular sinus under capsule
node divided into compartments
>cortex: outer region, B cells arranged as follicles, surrounded by paracortex of T cells
>medulla: contains medullary cords made of lymphocytes, plasma cells, macrophages, and fibroblasts, between cords are medullary sinuses
What animal has an inverted lymph node structure?
Pig-nodules located in center, surrounded by paracortex, then medulla
Why do lymphocytes recirculate?
- optimizes different cell populations required for induction of immune response
- facilitates interaction of small numbers of antigen-reacitve cells with specific antigen
- disseminates immune response throughout body
- disseminates memory cells throughout body
What is the regional immune system comprised of?
lymphoid tissues associated with skin and mucosal surfaces
Peyer’s patches
aggregates of lymphoid cells distributed between villi along intestine
B cell-rich follicles, T cell-rich interfollicular areas, macrophages and dendritic cells scattered throughout
Lamina propria
diffusely scattered throughout area
include lymphocytes, plasma cells, macrophages, dendritic cells, mast cells, eosinophils
Intra-epithelial cells
small number of cells among epithelial layer
appear to be type of T cell
important in protection against mycobacterial infection
Tonsils
lymph node-like structures asscoated with upper pharynx, lower cecum/rectum junction
Mesenteric lymph nodes
large string of lymph nodes that drain GI tract
includes Peyer’s patches and lamina propria
highly reactive
Pulmonary/mediastinal lymph nodes
one or two lymph nodes drain each lung (pulmonary)
entire thoracic cavity (mediastinal)
What determines the ability to generate a mucosal immune response?
antigen type
dose
presentation
