2-overview of immune system I Flashcards by Fumeng Sun

4 major categories of pathogens immune response fight against

Virus-retrovirus
Parasite-filaria
Bacterium- M.tuberculosis
Fungus- C.albicans

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Different pathogens require…

different immune responses

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A major difference is between microorganisms we have to deal with is

Intracellular microorganisms – virus
Extracellular microorganisms – bacteria

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explain Intracellular & extracellular microorganisms and what are there impact on our immune response

-processed differently
-generate different types of responses
intracellular: replicate inside cell
extracellular: replicate outside of cell

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Immune response is….., involves….., sometimes can….

-Complex
-Involves molecules/cells/tissues over time
-In different locations
-Sometimes can result in life-long immunity

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2 interconnected immune responses

Innate immunity – 1st line of defense (fast/non-specific)
Adaptive immunity – highly diverse/specific

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organs & tissues in immune system

Bone marrow
Thymus
Lymphatics (lymphatic system)
Lymph nodes

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Primary (Central) lymph organs

where immune cells are generated

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example of primary lymph organs

Bone marrow
Thymus

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Secondary (PERIPHERAL) lymphoid organs

where immune cells are activated

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example of Secondary (PERIPHERAL) lymphoid organs

Lymph nodes - especially
Spleen
Mucosal associated lymphoid tissues (malt)
Other diffuse and loosely organized areas

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how are Secondary (PERIPHERAL) lymphoid organs connected together?

via blood & lymphatic circulatory systems

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Key cells of innate & adaptive immunity: different cells are ….

diffferent cells associated with different/both immunity

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what is immune cells also known as?

leukocytes or white blood cells

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where do immune cells originate from?

they originate in the bone marrow

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All mature blood cells arise from 1 single cell type

HSC, hematopoietic stem cell

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what is hematopoiesis

process HSCs differentiate into mature blood cells in bone marrow

what are the 2 lineages in the origin of immune cells?

Common lymphoid progenitor
Common myeloid progenitor

what cells does lymphoid lineage generate

Mainly adaptive immune cells:
B&T lymphocytes (cells)
ILC-innate lymphoid cells
(NK cells)

what cells does myeloid lineage generate

Most other leukocytes:
Granulocytes:
Neutrophils
Eosinophils
Basophils/Mast cells (inflammation/allergies)

Monocyte which eventually becomes macrophages

One cell that can arrise from both progenitor

Dendritic cells - bridge innate and adaptive immune system

what happens when the cells are developped?

reside in tissues/organs OR circulate in blood/in lymphatic system

red blood cells from myeloid lineage

erythrocytes: carry O2 to cells/tissues & can generate antimicrobial compounds

what does Megakaryocytes do…

give rise to platelets (blood clotting)

what happens to monocyte from myeloid lineage, what is its role?

migrate into tissues & differentiate into macrophages Repair/remodel, destroy pathogens, present antigens (triggers our immune response)

what are Macrophages/immature dendritic cells/neutrophils from myeloid lineage specialized for?

Phagocytosis, cellular uptake by engulfment

what can macrophages do?

phagocytosis & present anitgens to T cells

What happens to immature DC after it phagocytoses an antigen?

mature & migrate out of the location to another – to present antigen to T cells

what are Dendritic cells?

Key bridge in immune response: -this is how they bridge between innate & adaptive Activate adaptive immunity -most potent antigen-presenting cells – for activating naive T cells Involved in detecting infection

Lymphocytes (B&T cells): similarity & differences

Appear very similar Different sets carry different clusters of differentiation (CD) molecules on their surface

what are B&T cells responsible for?

adaptative immunity (Generate highly specific responses )

how is B&T cells specificity determined?

Specificity – determined by expression of receptors on cell surface B cells – B cells receptor (BCR) -Can be bound to membrane or secreted as antibodies T cells – T cell receptor (TCR) -Membrane bound

how do immune cells communicate with each other?

signaling molecules are produced by activated innate immunity -stimulate & direct adaptive immune response -function to communicate (between cells/inside cells) OR mediate interactions between cells

what does molecules do to cells they need to target? (5)

it can trigger changes in target cells: activation/signaling/migration/transcription/cellular differentiation

key types of molecules: (40

Secreted proteins Receptors on cell surface Intracellular signaling molecules & transcription factors Antigens

Secreted proteins communicate through (2), what are they & what do they do?

Communication through cytokines & chemokines Cytokines: messenger proteins secreted by certain cells Chemokines: type of cytokines that recruits specific to a site

Receptors on cell surface, what ar their roles

Cytokines & chemokines bind to target cells via specific receptors Cells can interact via receptors

Intracellular signaling molecules & transcription factors

Many stimuli result in intracellular (inside the cell) signaling – involves signaling proteins & transcription factors

Antigens (Ag)

-Key molecule targeted by immune response -Antigen (Ag) = any specific molecule that can trigger an immune response -Can be a protein (most) or nucleic acid/polysaccharide/lipid/organic chemicals/drugs

what is an epitope?

Specific portion of Ag recognized by a receptor on immune cell

How does Molecules mediate actions/changes

cells interact with each other via receptors – resulting in change (Cell migration) cells migrate to a higher concentration of chemokines