(4) Innate Immune System vs. Adaptive

What are the 3 main components of the innate immune system?

physical barriers, phagocytic cells, NK cells

What are 4 examples of physical barriers that are a part of the innate immune system?

epithelium, mucus, saliva, tears

Which 2 types of phagocytic cells are mostly present in the innate immune system?

macrophages, neutrophils

What kind of general reaction in the body does the innate immune system induce?

**elevated body temperature in order to fight off pathogens

fever

group of proteins in the blood as a part of the innate immune system that help antibodies and T cells kill their target

**includes the alternative & lectin pathways and the membrane attack complex

complement system

proteins (cytokines) secreted by T cells and other cells to aid and regulate the immune response

interferons

non-specific protein, produced in the liver, that is part of the innate immune system and becomes elevated during episodes of acute inflammation or infection

C reactive protein

The roles of normal flora in innate immunity:

- occupy ____ sites

- compete for ____

- produce substances which are ____ for some pathogens

- stimulate ____ ____ immunity

receptor, nutrients, toxic, cross protective

How can normal flora of the gut stimulate cross protective immunity?

may resemble foreign antigens, so it can sensitize the body against the pathogen

Is the innate immune system fast or slow?

fast

Is the innate immune system specific or non-specific?

non-specific

(molecules react to shared microbial structures)

Does the innate immune system have limited or expanded diversity?

limited

Does the innate immune system have memory?

no

Is the innate immune system primitive or specialized?

primitive

(seen in all members of the animal kingdom)

Is the innate immune system reliable? (i.e. Does it know how to recognize self vs. non-self cells?)

yes

Why is the skin able to provide an immune barrier?

outer keratinized layer

What do epithelial cells secrete in innate immunity?

peptide antibiotics

What do keratinocytes secrete in innate immunity if they are damaged?

cytokines and chemokines

epidermal macrophages that migrate to lymph nodes and present antigens to T cells (along with dendritic cells)

Langerhans cells

mechanism in which cilia transport mucus containing foreign material out of the respiratory tract

mucociliary escalator

compounds in the respiratory tract that contain microorganism-binding collectins, which target them for phagocytosis and/or complement

surfactants

What unique quality of the GI tract allows it to be an effective barrier in the innate immune system? (hint: kills microorganisms)

acidic pH

Does corneal resistance to infection result from innate or adaptive immunity?

innate

How do corneal epithelial cells provide a formidable barrier to microorganisms?

tight junctions

How can microorganisms on the cornea be flushed down the lacrimal duct?

tear flow

phagocytic cell receptors that recognize and bind specific foreign molecules; embedded in plasma membranes and endosomal membranes within cells

**different ones bind to different components of microbes

toll-like receptors (TLRs)

Where are TLRs found?

plasma and endosomal membranes

What are the ligands for TLRs?

foreign antigens

Different toll-like receptors bind to different components of microbes. For example, what does TLR-4 bind to?

LPS

(lipopolysaccharides in bacteria that are endotoxins)

phagocytic cell receptors that bind modified methionine on bacteria

N-formyl methionine receptors

phagocytic cell receptors that bind bacterial glycoproteins ending in a terminal mannose residue

mannose receptors

large granular lymphocytes (10%) in blood and peripheral lymphoid organs that function to eliminate cellular reservoirs of viral infection

natural killer cells

What activates NK cells?

IL-12

What secretes IL-12 that activates NK cells?

macrophages

When NK cells are activated by IL-12 (secreted by macrophages), they in turn secrete IFN-gamma, which does what?

stimulates macrophages to be better at killing phagocytosed microbes

What do NK cells secrete?

IFN-y (gamma)

What molecules are our self cell "ID badges" for the body?

MHC

Do MHC class I molecules stimulate or inhibit NK cytotoxicity?

inhibit

Do NK cells target cells with or without MHC class I molecules?

without

(since it inhibits the NK cells)

NK cells encountering (self) MHC class I proteins receive signals to not react via the binding of receptors?

killer immunoglobulin-like receptors (KIRs)

MHC class I molecules are down regulated in what two types of cells?

virally infected cells, cancer cells

In virally infected cells and cancer cells, are MHC class I molecules up or down regulated?

down

(so they won't inhibit NK cytotoxicity as much, therefore the NK cells can be activated and kill these bad cells)

How does direct cell-to-cell signaling occur in cell cytotoxicity?

surface receptors

How does indirect cell-to-cell signaling occur in cell cytotoxicity?

cytokines

Granules containing proteins that damage target cells function in cell cytotoxicity by doing what to their membranes?

poking holes

Cell cytotoxicity may occur via direct cell-to-cell signaling using cell surface receptors, indirect cell-to-cell signaling using cytokines, or granules containing proteins that damage target cells. Ultimately, cells kill other cells by inducing what process to occur?

apoptosis

(clean cell death, not a lot of collateral damage)

cytokine of innate immunity that is made by macrophages and T cells and activates endothelial cells & neutrophils, causes the liver to produce acute phase proteins , induces muscle and fat catabolism, cause apoptosis, and induces fever

TNF

cytokine of innate immunity that is made by macrophages, endothelial cells, and some epithelial cells and activates endothelial cells, induces fever, and causes the liver to produce acute phase proteins (like CRP)

IL-1

general cytokines of innate immunity that are made by macrophages, endothelial cells, T cells, fibroblasts, & platelets and function to induce chemotaxis and activation in leukocytes

chemokines

cytokine of innate immunity that is made by macrophages & dendritic cells and induces IFN-y synthesis and increased cytolytic activity in NK cells and T cells, as well as TH1 differentiation in T cells

IL-12

cytokine of innate immunity that is made by NK cells & T lymphocytes that is involved in activation of macrophages and stimulation of some antibody responses

IFN-y

acute phase protein that recognizes microbial carbohydrates and coats microbes for phagocytosis or lysis by complement via the lectin pathway

mannose binding lectin (MBL)

What does mannose binding lectin recognize on microbes?

carbohydrates

acute phase protein that binds to phorylcholine on microbes and coats the microbes for phagocytosis by macrophages with the namesake receptor

C reactive protein (CRP)

What does C-reactive protein recognize on microbes?

phorylcholine

What kind of cells have CRP receptors?

macrophages

What does adipose tissue secrete in order to help with pathogen destruction?

cathelicidin

glycoproteins secreted by corneal epithelial cells that aggregate bacteria and inhibit epithelial colonization

mucins

cationic peptides secreted by corneal epithelial cells that inhibit growth or viability of many bacterial pathogens

beta defensin

hydrolytic enzyme secreted by corneal epithelial cells that acts against gram positive bacteria

lysozyme

refers to highly conserved and essential components of microbes; conserved molecules present on groups of pathogen

Example: bacteria might have one thing that is different from what fungi have

pathogen associated molecular patterns (PAMPs)

refers to cellular receptors that form diverse recognition elements and mediate the recognition of PAMPs

Example: toll-like receptors on phagocytes - each family recognizes certain molecule patterns

pattern recognition receptors (PRRs)

Do PAMPs belong to pathogens or cells?

pathogens

Do PRRs belong to pathogens or cells?

cells

Cells of the innate immune system recognize [PAMPs/PRRs] found on the target cell via [PAMPs/PRRs].

PAMPs, PRRs

The innate immune system can recognize the lack of self antigens in order to not induce autoimmunity because foreign pathogens don't have what molecule present on their surface?

MHC-I

(absence of MHC-I leads to cytotoxicity via NK cells)

Which of the following is NOT part of the innate immune system?

A. Skin

B. Neutrophils

C. Blood

D. NK cells

E. Tears

C

How are B cells (in the adaptive immune system) involved in antigen recognition?

produce antibodies

How are T cells (in the adaptive immune system) involved in antigen recognition?

T cell receptors (TCRs)

set of cell surface proteins essential for the adaptive immune system to recognize foreign cells

found on the outside of all self cells to allow them to present antigens

major histocompatibility complex (MHC)

Is the adaptive immune system fast or slow?

slow

Is the adaptive immune system specific or non-specific?

specific

Does the adaptive immune system have limited or expanded diversity?

expanded

Does the adaptive immune system have memory?

yes

Is the adaptive immune system primitive or specialized?

specialized

(first found in early vertebrates)

refers to adaptive immunity in which a patient acquires a disease and then recovers

active natural

refers to adaptive immunity in which a patient is vaccinated

active acquired

refers to adaptive immunity in which a mother passes immunity to the child either transplacentally or through breast-feeding

passive natural

refers to adaptive immunity in which the patient receives preformed immune components (e.g., gamma globulins)

passive acquired

The adaptive immune system recognizes "foreignness" in a highly specific manner via unique receptors that are generated via DNA rearrangement during development.

This gene rearrangement enables the immune system to generate lymphocytes capable of doing what?

responding to tons of foreign invaders

(receptors are not "hardwired")

Do T cells recognize processed or unprocessed antigens?

processed

(already processed by another cell - requires APC)

Do B cells recognize processed or unprocessed antigens?

either

Which part of the immune system recognizes PAMPs found on the target cell via PRRs?

innate

Which part of the immune system recognizes and responds to specific antigens via receptors specific for that particular antigen?

adaptive

Which part of the immune system recognizes broad categories or patterns of foreignness?

innate

Which part of the immune system doesn't recognize self-antigens?

innate

Which part of the immune system specifically distinguishes between self and non-self antigens?

adaptive

Which part of the immune system is pre-existing?

innate

Which part of the immune system has a "lag time" before the first response can be detected?

adaptive

How long does it take for the first adaptive response to be detected?

7-10 days

How long does it take for the second adaptive response to be detected?

3-4 days

(secondary response is faster and stronger)

Which part of the immune system has no memory?

innate

Which part of the immune system possesses memory of a previous infection?

adaptive

True or false: The innate and adaptive immune responses constantly interact with one another.

true

(the innate response can initiate the adaptive response and the adaptive response will regulate the innate response)

Nonspecific immune responses...

A. come into play whether or not there has been prior experience with the offending agent

B. are triggered by invasion of infectious microorganisms, chemical injury, mechanical trauma, or burns

C. are mediated by lymphocytes

D. have characteristics A and B

E. have none of the above characteristics

D