immuno lec 3 lymphocytes Flashcards
What is the # of WBCs in 1 microliter of blood in a healthy individual?
4,500-11,000
(7,500 mean)
What are the types of white blood cells and their cell count per microliter?
Neutrophils (4400)
Eosinophils (200)
Basophils (40)
Lymphocytes (2500)
Monocytes (300)
total (7400)
What happens to WBC number during infections?
No change in blood WBC count and the response is usually localized to the tissues.
Having extremely low neutrophils in the blood is called:
Neutropenia (can be congenital or acquired)
To what cells do APCs signal to and what are the general effects?
lymphocytes, it induces proliferation and differentiation.
How can naive T cells be activated?
Only by dendritic APCs
What are dendritic cells and where are they found?
Phagocytic cells with antigen-presentation capability. They are found in organ parenchyma, mucosal epithelium, and lymphoid tissue.
What are the 2 true types of dendritic cells and their functions?
conventional dendritic cells, mainly for antigen presentation to T cells.
Plasmacytoid dendritic cells, used for interferon type 1 synthesis upon viral stimulation
What are follicular dendritic cells and their functions?
Cells with membranous projections, found in germinal centers surrounded by activated B cells in lymph nodes and spleen. They capture Ag-Ab and present them to B cells without modifications.
What cells bind to macrophage APC and what are the effects?
Helper T cells, results in activation of these T cells and production of molecules that increase phagocytic function
Where do B cells present their antigens?
lymph nodes and spleen to T cells .
How does the MHC 1 work?
proteins in most cells are degraded by a proteosome and are then displayed on MHC 1, which works as an inhibitory signal for natural killer cells.
Cytotoxic T cells will lyse the cell if it presents antigens on MHC 1
How and where does MHC 2 function?
Found on dendritic and B cells in addition to macrophages and some endothelial cells. MHC 2 displays antigens for different lymphocytes like helper T cells
What are the types of lymphocytes in the body?
Natural killer cells
T cells
B cells
How do natural killer cells function?
works in innate immunity against intracellular infections. They are able to lyse cells without stimulation. To be stopped, inhibitory signals like MHC 1 must be present on the surface of the cell.
Where do B and T cells originate and where do they mature?
Both from bone marrow.
B cells early maturation in bone marrow
T cells mature in the thymus
What are CDs
Cluster of differentiation. surface molecules that are used to identify cells and serve as ligands or receptors.
What do T cells do?
When detecting an antigen on MHC 1, cytotoxic T cells lyse the infected cell. When detecting MHC 2, helper T cells release cytokines and induce phagocytosis and inflammation.
What is humoral immunity and cell-mediated immunity?
Humoral: mediated by antibodies
Cell-mediated: mediated by T lymphocytes
What are perforin granzymes?
Molecules released by killer T cells and have a serine protease function that triggers apoptosis of the cell via caspase cascade.
What is the distribution of lymphocytes in the body?
2% blood
10% bone marrow
15% mucosal lymphoid tissue
65% lymphoid organs like the spleen
How are T cells able to bind to each possible antigen?
Each clone of the T cells has a unique antigen receptor, there are countless T cells so new antigens can be detected.
How are T cells able to form different antigen receptors with the same genes?
Genes encoding for antigen receptors are recombined during the maturation of T cells.
