Immunology Overview Dr. Bossaer Flashcards by o e

All cells of the immune system are derived from ___

pluripotent cells

differentiation is stimulated by cell-to-cell interaction and hematopoietic growth factors

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Which molecule makes dendritic cells the most potent antigen-presenting cells (APC)?

MHC-II on the surface (presenting antigens of pathogens)

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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

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When do B-lymphocytes produce antibodies?

When activated and differentiated into a plasma cell

the antibodies are then specific to an antigen

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Which immune cells are considered Granulocytes?

-Neutrophils (fight bacteria)

-Basophils (blood) - release histamine
-Mast cells (tissue) - release histamine, heparin, 5HT3

-Eosinophils (fight parasites)

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Basophils are found in the ___, Mast cells are found in the ___

Basophils in the blood
Mast cells in the tissue

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What is the function of a Macrophage and a monocyte?

they are closely related

Macrophage: Phagocytosis

Monocyte: antigene-presenting cell (APC)

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Monocytes are found in the ___, Macrophages are found in the ___

Monocytes in the blood
Macrophages in the tissue

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Which immune cells kill virally infected or mutant cells?

NK cells

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Which immune cells help stimulate the immune system by upregulating antibodies?

CD4+ T-helper cell

help the immune system to target an antigen

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Which immune cells fight viral infections and cancerous cells intracellular?

CD8+ T-cells

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CD4+ T-cells work intra or extracellular?
CD8+ T-cells work intra or extracellular?

CD4+ T-cells: extracellular

CD8+ T-cells: intracellular

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Which (4) immune cells are considered Lymphocytes?

-NK cells
-CD4+ T-cells
-CD8+ T-cells
-B-cells

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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)

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How does MAC work?

complement molecules (C5b, C6, C7) come together and form a hole in the membrane of a cell

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Which immune cells are most common in the bloodstream?

Neutrophils (40-60%)

-fight bacterial infections

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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)

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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