Immunology Overview Dr. Bossaer Flashcards
All cells of the immune system are derived from ___
pluripotent cells
differentiation is stimulated by cell-to-cell interaction and hematopoietic growth factors
Which molecule makes dendritic cells the most potent antigen-presenting cells (APC)?
MHC-II on the surface (presenting antigens of pathogens)
T-lymphocytes have TCR (T-cell receptors) binding to different antigens. T/F
False.
TCRs of a T-lymphocyte bind to only one antigen
->same with IgM, IgD, IgA, IgG of B-lymphocytes
When do B-lymphocytes produce antibodies?
When activated and differentiated into a plasma cell
the antibodies are then specific to an antigen
Which immune cells are considered Granulocytes?
-Neutrophils (fight bacteria)
-Basophils (blood) - release histamine
-Mast cells (tissue) - release histamine, heparin, 5HT3
-Eosinophils (fight parasites)
Basophils are found in the ___, Mast cells are found in the ___
Basophils in the blood
Mast cells in the tissue
What is the function of a Macrophage and a monocyte?
they are closely related
Macrophage: Phagocytosis
Monocyte: antigene-presenting cell (APC)
Monocytes are found in the ___, Macrophages are found in the ___
Monocytes in the blood
Macrophages in the tissue
Which immune cells kill virally infected or mutant cells?
NK cells
Which immune cells help stimulate the immune system by upregulating antibodies?
CD4+ T-helper cell
help the immune system to target an antigen
Which immune cells fight viral infections and cancerous cells intracellular?
CD8+ T-cells
CD4+ T-cells work intra or extracellular?
CD8+ T-cells work intra or extracellular?
CD4+ T-cells: extracellular
CD8+ T-cells: intracellular
Which (4) immune cells are considered Lymphocytes?
-NK cells
-CD4+ T-cells
-CD8+ T-cells
-B-cells
What are the (4) functions of the Complement system?
-stimulate chemotaxis (attract neutrophils to the site of infection)
-Opsonize pathogens (prevent pathogen entry or flagging)
-clear immune complexes (deposition of immune complexes can lead to inflammation and pain
-cell lysis via MAC (membrane attack complex)
How does MAC work?
complement molecules (C5b, C6, C7) come together and form a hole in the membrane of a cell
Which immune cells are most common in the bloodstream?
Neutrophils (40-60%)
-fight bacterial infections
How do Neutrophils get to the site of infection?
via L-selectin and adherence molecules -> then migration into the tissue
-then directed to the pathogen via Chemotaxis (through cytokines like IL-8)
What is demargination?
Neutrophils are pushed into the middle of the blood vessels (instead of the outside (margin)
-can be caused by corticosteroids
Why do corticosteroids cause higher WBC counts?
better detection of WBC doesn’t mean that there are more WBC
-steroids are also immunosuppressive bc they cause de-margination and neutrophils being less efficient in the center of the blood vessels
What are the (3) ways Neutrophils kill bacteria?
-direct phagocytosis (without opsonization, they detect pathogens by bacterial flagella, dsRNA, fungal zymosan)
-directed phagocytosis (without opsonization)
-release of granules after phagocytosis (oxidative metabolites of granules)
What do mature and immature Neutrophils look like?
Normal: polymorphic nucleus
Immature: Band-like nucleus (sometimes go from the bone marrow into the bloodstream when in need)
Macrophages are found in which organs or tissues?
-Kupffer cells in the liver
-Microglial cells in the brain
-Osteoclasts in the bone
Remember: in the bloodstream -> Monocytes
MHC-II is found on which cells?
antigen-presenting cells
-Macrophages
-dendritic cells
-B-cells
-TH1-cells
-T-follicular helper cells
-Treg cells
MHC-I is found on which cells?
on all nucleated cells
-NOT RBC
MHC-I present peptides made inside the cell, if not recognized by CD8+ T-cells it will be killed (could be a virus or a cancer cell)
Which (3) interactions are required to activate a CD4+ T-cell?
-Signal 1: MHC-II (dendritic cell) to TCR (CD4+ cell)
-Signal 2: CD40 (DC) to CD40-L (CD4+)
-Signal 3: IL-2 (DC) to IL-2 receptor (CD4+)
IL-2 is a target for reducing autoimmune respones
How are CD8+ T-cells activated?
often via IL-2
How do activated cytotoxic T-cells (CD8+) kill?
-Perforin system
Perforins (holes in the cells)
Granzymes (entering cells and induce apoptosis)
-Fas-Fas Ligand pathway (Fas binds to Fas-Ligand causing apoptosis)
How do cancer cells escape the immune system?
-upregulation of anti-apoptotic elements (like BCL2)
-downregulation of Fas
What are ways to reduce lymphocyte activity?
-CTLA expression
-PD-1 expression
-Fas expression
-CD4+ Tregs (antigen-specific, requires binding)
How are NK cells different from cytotoxic CD8+ T-cells?
They dont require activation in the same way as CD8+ cells
-still need a form of activation
How does B-cell activation work?
-Ig on the surface recognizes bacteria -> Phagocytosis
-present bacterial antigen through MHC-II to CD4+ T-cells
-CD4+ produces cytokines (IL-4, 5, 6, 10, 13) to activate B-cells that multiply and pump out free antibodies
-also formation on memory B-cells that get activated faster when in contact with the bacteria again
What are the types of antibodies and what does the structure look like?
-IgM, IgG, IgA, IgE, IgD
-Fc (constant) region binds to Fc-receptors phagocytes
-Fab is variable and binds to unique antigens
Which of the immunoglobulins indicate a recent infection?
IgM (pentamer) first responder
Which of the immunoglobulins indicate immunity to a pathogen?
IgG - 2nd responder
most prevalent Ig (indicate B-cells that still produce antibodies)
Which Immunoglobulin crosses the placenta?
IgG
-last for 3 months
-after 3 months the baby starts producing their own IgG
Which immunoglobulin is secreted in body fluids?
IgA (dimer), present in saliva, tears, GI, and respiratory tract, breast milk
-helps to prevent Cold and Flu (preventing pathogens from entering the cells)
What is the function of IgE?
Elimination of parasites
-Histamine release (bound to Fc receptors of Mast cells and antigen-presenting cells)
What is the function of IgD?
-not understood
-high IgD concentration correlates with auto-immune diseases
Function of IL-2
activate
T-cells
B-cells
NK-cells
Function of TNF-α
activate
-Neutrophils
-endothelial cells (activated: cause inflammation, coagulation)
-lymphocytes
-liver cells to produce acute phase proteins
produced by Macrophages, NK-cells, T-cells, B-cells, mast cells
Function of TNF-β
Tumoricidal
Which Cytokine has a negative effect on the immune system (immunosuppressive)?
INF-β
reduce IL-17, used as a drug for autoimmune disorders
Where in the lymph node are more B-cells and where are more T-cells?
B-cells in the Cortex
T-cells in the Paracortex
Macrophages in the medulla
