Innate Immune Reponse

blood cell count from largest to smallest

plasma

RBC
WBC

hematopoiesis

all cells in our blood come from a hematopoietic stem cell

what type of blood are leukocytes

white blood cells

white blood cells

granulocytes

mononuclear phagocytes

lymphocytes

types of granulocytes

neutrophils

basophils

eosinophils

neutrophils

granule contains the enzyme MPO that directly breaks down microbe structure

basophils

granule contains histamine which activates inflammation and allergic reactions

eosinophils

granule has major basic protein that binds to helminth cell walls and break them down

types of mononuclear phagocytes

monocytes

macrophages

dendritic cells

monocytes

• circulate in the blood

• are precursors to macrophages and dendritic cells

macrophages

• in tissues to eliminate pathogens via phagocytosis

• secrete cytokines by PRR

dendritic cells

• in tissues as sentinel cells

  • initiate adaptive immune response by traveling to lymph nodes upon activation

types of lymphoid cells

T cells

B cells

T cells

release cytokines

B cells

secrete antibodies to promote other cells to kill microbe

a sample tissue is processed and stained for immune cell infiltration. it is found that a granulocyte is present that stains positive for an MPO signal. what type of immune cell is this?

neutrophil

what lymphocytes are found in the blood?

T cells

B cells

Innate immunity

immunity youre born with

adaptive immunity

immunity that develops over lifetime

what does the first line of defense consist of

• physical barriers

• chemical barriers

• microbiomes

physical barriers: skin

• layers of skin keeps the microbe out

• dead skin at the top to create wall

  • sheds every 28 days

physical barriers: mucous membranes

• barrier of epithelial cells coated in thick mucous layer

  • mucus is made of thick glycoproteins

    • trab microbes

    • prevent tracts from drying out

physical barriers: microbiomes

• produce antimicrobial products

• nutrient and area competition

chemical barriers: enzymes

• lysozyme (tears/saliva)

  • degrades bacteria cell walls

• peroxidase (saliva)

  • kill bacteria via hydrogen peroxide

chemical barriers: antimicrobial peptides

short peptides by host cells to kill bacteria

Which of the following represents a physical barrier for the body against

pathogens?

A. sweat secreted from ducts in the skin

B. lysozyme found in saliva of mouth

C. cilia movement in respiratory epithelial cells

D. decreased pH in vaginal fluid

C. cilia movement in respiratory epithelial cells

The skin microbiome can prevent pathogens from binding to the surface of

the gut epithelium. How might the skin microbiome do this?

A. promotes increased gut mucus production

B. competes for nutrients on the gut membrane surface

C. secretes excess sebum to prevent microbe growth

D. use microbial cilia to push other pathogenic microbes away

B. competes for nutrients on the gut membrane surface

what happens when the first line of defense is breached?

sensory systems are activated

steps for cytokine activation

• host cells recognizes Pathogen Associated Molecular Pattern (PAMP) via pattern recognition receptors (PRR)

• production and secretion of cytokines

  • alarm for all out immune response

sensory: complement system activation

• C1 - C9 (complement proteins) and antibodies (made by B cells) are circulating in blood in an inactive state

• antibodies recognize foreign pathogen and bind onto it

• complement proteins bind to antibody

  • C3 is split into Ca and Cb to become activated

    • = effector

effector: cytolysis

• C9 embeds itself onto pathogen

• Membrane attack complex

  • creates a pore (hole)

  • water rushes out of pathogenic cell

    • = death of cell

effector: opsonization

• C3b binds around pathogen to make it “tastier” for macrophage

• macrophage sees tasty pathogen

• PRR on macrophage bind onto pathogen

• pathogen enters via endocytosis

• phagosome is formed inside macrophage

• lysosome fuses with phagosome to make phagolysosome

  • pathogen gets broken apart by enzymes

effector: inflammation

• increase vasodilation

  • more immune cell in blood

  • more immune cell activity

• cytokines gather in one place

  • chemotaxis (signal where cytokines are grouped together alert the body)

  • neutrophils are recruited out of the blood (increased immune cell recruitment)

effector: fever

• caused by the release of specific cytokines

  • interleukin 1

  • tumor necrosis factor alpha

• triggers the hypothalamus to increase body temperature

  • metabolic activity increases for immune cells to work more efficiently

  • prevent microbial growth/spread

A complementary protein is activated in infected tissues followed by pathogens breaking open due to formation of small holes (MAC) in their membranes upon further complement effector functions. Which complement effector pathway is responsible for this?

A. opsonization

B. cytolysis

C. increased inflammation

D. neutralization

B. cytolysis

A macrophage successfully engulfed and endocytosed a bacteria into a

phagosome. What would happen next in this pathway?

A. The pathogen would be opsonized by C3 proteins.

B. The phagosome would fuse with a lysosome for degradation.

C. The pathogen would being to breakdown in the acidic phagosome.

D. The pathogen would further stimulate a pattern recognition receptor for

cytokine release.

B. The phagosome would fuse with a lysosome for degrada