Chapter 14 Innate Immunity

immunology

study of organisms immune defenses

immunity

state of being immune

innate immunity

against a broad array of microbes

adaptive immunity

produced in response to a specific foreign antigen, get memory

antigen

substance that triggers an immune response (non-self)

normal flora

bacteria that normally inhabit body surfaces

Hematopoietic stem cell

formed in bone marrow, have potential to become any type of blood cell

hematopoiesis

stem cell to specific blood cell

cytokines

signaling molecule that produces a response

opsonization

coat surface of microorganism with molecule easily recognized by phagocytes

inflammation

a localized response to an injury or to the destruction of tissues

diapedesis

the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation

What first line defenses function as physical barriers to the entry of pathogens?

skin, mucous membranes, muco-ciliary escalator, flushing, peristalsis of GI

How do each of these physical barriers function?

barriers that separate the interior of body from environment, prevent microbial entry

What antimicrobial substances function as first line defenses?

Lysozyme, peroxidase enxymes, lactoferrin/transferrin, fatty acid/acidic, defensins

Lysozyme

bodily secretions specialized WBC, breaks beta 1-4 glycosidic bond between NAG and NAM

Peroxidase enzymes

hydrogen peroxide superoxide anion, steals electrons

Lactoferrin and transferrin

siderophores tightly bind to iron to get where it needs to go, limit access of iron to viruses

Fatty acids and acidic environments

sebaceous secretions inhibit growth, denature proteins

Defensins

small cationic peptides that poke hole in cell membrane

How does normal flora function as a first line defense mechanism?

make difficult for potential pathogen to attach

What leukocytes are considered to be granulocytes?

eosinophils, basophils, neutrophils

Neutrophils

over half in circulation, primary phagocyte bind engulf destroy nonself

Eosinophils

destroy parasites (tapeworms, roundworms, hookworms)

Basophils

allergic reactions (seasonal allergies, dust/pollen)

What leukocytes are considered to be agranulocytes?

Monocyte, lymphocytes (T cells and B cells)

Monocytes

phagocyte in bloodstream, can leave to transform into macrophage or dendritic cell

Lymphocytes

T cells, B cells, and NK cells; help eliminate precancerous cells

What leukocytes are classified as lymphocytes?

T cells and B cells

T cells

helper T: coordinates immune response, cytotoxic T: kill infected and abnormal cells

B cells

become plasma cells, secrete antibodies

NK cells

identify and kill infected/abnormal cells

What leukocytes can function as phagocytes?

neutrophils, monocytes, macrophages, dendritic cells

Which phagocyte is the first to respond to an infection?

neutrophil

What is the function of phagocytes?

engulf and destroy antigens

How do cells in the immune system communicate with each other?

cell surface receptors bind ligands that produce a cellular response

Chemokines

induce chemotaxis, attract WBC to area of infection

Colony stimulation factors

drive process of hematopoiesis, differentiation

Interferons

antiviral, induce fever, inflammation

Interleukins

produced by leukocytes cause response in other leukocytes

Tumor necrosis factor

inflammation, apoptosis

What sensor systems exist to detect the presence of foreign antigens and how do they function?

Pattern Recognition Receptors (PRRs), B and T cell receptors

What are toll-like receptors

protein receptors within cell membrane of macrophages

what types of antigens do toll-like receptors detect?

pathogen associated molecular patterns (PAMPs), peptidoglycan, flagella, LPS

What happens when toll-like receptors bind foreign antigens?

release pro-inflammatory cytokines

What is the function of NOD-like proteins?

detect bacterial PAMPs

Of RIG-like proteins?

detect viral PAMPs (double stranded RNA, uncapped RNA)

What are PAMPs and DAMPs?

pathogen associated molecular patterns and damage associated molecular patterns

What is the complement system?

series of proteins in inactive state in circulation

In what ways can the complement system be activated?

alternative pathway, lectin pathway, classical pathway

What are the possible results of activating the complement system?

inflammation, attack complex, opsonization

Be familiar with the function of C3a, C5a, and C3b as well as the components of the membrane attack complex.

C3a and C5a

chemokine, WBC to area, inflammation

C3b

opsonization, or combine with C5 to produce C5a or C5b

C5b

initiates formation of membrane attack complex, form pore that leaks out cytoplasmic contents

How do interferons function to detect viruses and prevent their spread?

activating pattern recognition receptors (PRRs) triggers interferon release, signals nearby cells to produce antiviral proteins that block viral replication and spread

Be familiar with the steps involved in phagocytosis.

chemotaxis, recognition and attachment engulfment, phagosome maturation, destruction and digestion, exocytosis

How does opsonization enhance phagocytosis?

By coating microbes with C3b, promoting attachment to phagocytes

How do phagocytes kill ingested microbes?

lysosome combines with phagosome create phagolysosome containing digestive enzymes

What are the signs of inflammation?

redness, heat, swelling, pain

What are the triggers of inflammation?

microbial products (LPS, flagellin, bacterial DNA, PAMP's), microbial surfaces, tissue damage (DAMP's)

How do microbial products (LPS, flagellin, bacterial DNA, PAMP's) trigger inflammation

stimulate toll-like receptors to release pro-inflammatory cytokines

How do microbial surfaces trigger inflammation

alternate pathway, C3a and C3b attract WBC to area

How do tissue damage (DAMP's) trigger inflammation

coagulation cascade (blood clot), bradykinin (dilate blood vessels)

Be familiar with the general steps in an inflammatory response and how they occur.

cytokines vasoconstrictor, vasodilation flush and plasma (has complement proteins, antibodies, clotting factors, siderophores), diapedesis, lymphocytes, macrophages

What are the differences in an acute and chronic inflammatory response?

acute: neutrophils clearance and healing, chronic: macrophages spew toxic chemicals causing damage

What is septic shock and how is it triggered?

inflammatory response to endotoxin (LPS)

How can death result from septic shock?

vasodilation that decreases blood pressure, blood cools forming clots, organ failure/death

What is a pyrogen?

any molecule stimulate fever

What are examples of endogenous and exogenous pyrogens?

endogenous: interleukin 1, exogenous: LPS

What are the potential benefits of a fever response?

inhibits growth of pathogens, speeds up immune response

What is apoptosis?

programmed cell death

What is pyroptosis?

apoptosis with inflammation

What is the function/purpose of apoptosis?

used to eliminate virally infected cells and self-cells that are no longer needed

What are the characteristics of a cell undergoing apoptosis?

cell shape changes, DNA degraded, parts of cell bud off shrinking the cell size