Immunology Flashcards
Where in the lymph node do B cells localize?
Localized in the follicle of the lymph node.
Primary follicles are in the outer cortex and are dormant.
Secondary follicles are in the center germinal centers and are very active.
What is found in the lymph node medulla?
Medullary cords and medullary sinuses.
Communicate with efferent lymphatics and contain reticular cells and macrophages.
What is found in the paracortex of the lymph node?
Houses T cells
This is the region between the cortex and follicles of the medulla.
B and T cells enter from the blood here and not well deveoped in DiGeorge syndrome.
Which part of the lymph node is not well developed in patients with De George syndrome?
Paracortex
In extreme immune responses, which part of the lymph node enlarges?
The paracortex
the right lymphatic duct drains what?.
The entire right side of the body above the diaphragm
The left lymphatic duct drain what?
Drains everything except for the right side of the body above the diaphragm.
EMPTIES INTO THE LEFT SUBCLAVIAN AND INTERNAL JUGULAR VEINS.
where are T cells found in the spleen?
These are found in the periarterilar lymphatic sheath within the white pulp of the spleen.
Where are B cells found in the spleen?
The follicles within the white pulp of the spleen.
what is the marginal zone in the spleen and what can be found here?
Marginal zone is between the red and white pulp containing the antigen presenting cells and specialized B cells.
they capture blood born molecules here.
Why is the spleen so important for encapsulated bacteria?
The macrophages in the spleen remove encapsulated bacteria.
Thus, when a patient misses a spleen they are at increased risks.
Howell jolly bodies, target cells, thrombocytosis, and lymphocytosis is all seen after…
After a splenectomy.
Howel jolly bodies are nuclear remnants
Thrombocytosis is loss of sequestration and removal
Lymphocytisis is loss of sequestration of lymphcytes.
what is the thymus important for?
Differentiation and maturation of T cells!
Which pharyngeal pouch does the thymus evolve from?
The third pharyngeal pouch.
From mesenchymal origin
What is found in the cortex of the thymus?
Immature T cells
Medulla is pale with mature T cells and hassall corpuscles containing epithelial reticular cells.
Which type of immunity relies on toll-like receptors for antimicrobial activity?
This is in innate immunity.
TLR’s recognize patterns (PAMPS)
such as LPS, flagellin and ssRNA.
What do MHC I cells bind?
TCR and CD8 on T killer cells.
these present through synthesized antigens
Where are antigen peptides loaded onto MHC I in the cell?
By the rough endoplasmic reticulum
What protein is associated with MHC I ?
B2 microglobulin
What cells present MHC II?
Antigen presenting cells present exogenously synthesized antiges to CD4 helper T cells.
What cells read MHC II?
CD4 T cells.
How do natural killer cells work?
Work by using perforin and granzymes to induce apoptosis.
What upregulates natural killer cells?
IL-2
IL-12
IFN-alpha
IFN Beta
What do CD4 cells do?
CD4 helper T cells help to make B cells compose antibodies
What is positive selection of T cells?
Thymic cortex, T cells that express TCRs capable of BINDING SELF MHC molecules survive.
What is negative selection of T cells?
Thymic medulla
T cells express TCRs with high affinity for self antigens undergo apoptosis.
Where does positive selection of T cells occur?
In the thymic cortex
Where does negative selection of T cells occur?
In the thymic medulla.
What do TH1 cells secrete to activate macrophages?
TH1 secretes interpheron gamma to activate macrophages and CD8 cells.
What cytokines activate TH1 cells?
IFN gamma and IL-12
IL-4 and IL-10 from TH2 cells deactivate TH1 cells.
What cytokines are secreted by TH2 cells?
IL-4
IL-5
IL-10
IL-13
What do TH2 cells do?
Recruit eosinophils for parasite defence and promotes IgE production by B cells
What activates TH2 cells?
IL-4