Innate Immunity - 1

The ____ system is known as the immediate immune response.


(T/F) The innate immune system is a generalized and specific system

(it IS generalized but is NON-specific)

Mucosal barriers, complement system, and phagocytes are examples of the _____ immune system.


The _____ system is known as the specific immune response.


What are the first two lines of defense barriers we have?


What characteristics of the skin help with protection?

Microbiota - competition with invaders
Multilayered - shedding skin gives significant outward movement
Low permeability - tight junctions in skin help prevent penetration

What characteristics of mucosa help with protection?

Secretions - may contain lysozyme and various enzymes used for digestion
pH - low pH does not allow bacteria to live in those conditions
Cilia - trap molecules and invaders

____ cells are cells in the GI system that have immune clusters that are used when phagocytosis of bacteria takes place.

M cells

How many plasma proteins make up the complement system?

Over 30

Proteins for the complement system are made in the _____.


Problems in the liver will cause problems in the _______ system, thus allowing them to become sick due to a slow immune response.


Is the complement system specific or non-specific?

NON-specific (it is part of the innate immune system)

C3 gets cleaved into _____ & _____

C3a (smaller)
C3b (bigger)

What is the function of C3a?

Recruits phagocytes

What is the function of C3b?

It attaches to pathogen and "tags" it for destruction (complement fixation)

What are the 3 pathways of complement system activation?

1. Classical
2. Lectin
3. Alternative

What do all 3 pathways of the complement system do to C3

They all cleave C3 into C3a and C3b

Which is the 1st pathway to act in the complement system?


In the Alternative Pathway C3 is HYDROLYZED with water creating _____


What factor attaches to iC3?

Factor B (Baby attaches)

What factor cleaves factor B?

Factor D (he's a Dick he split them)

What is the complex that cleaves C3 into C3a and C3b in the alternative pathway?

iC3Bb (C3 convertase)

What is iC3Bb also called?

C3 convertase

Why do we need to regulate the Alternative Pathway?

Without regulation, pt will have high levels of activated C3 all the time. So when there is bacteria, there is poor C3 activation on the bacteria.

______ stabilizes C3 convertase C3bBb on a pathogen surface and prevents degradation.

Properdin (factor P)
(Keeps the factor ON)

What factor/s can help C3 convertase degrade?

factor H & I

What is opsonization again?

When C3b attaches to bacteria to mark it for phagocytosis

The _____ receptor on a macrophage binds to high density C3b fragments on bacteria.

CR1 (complement receptor 1)

What 2 proteins prevent SELF opsonization, are on self cells and don't allow C3b to attach.


What is MAC?

Membrane Attack Complex: complement proteins that perforate microorganisms and destroy the microorganism directly.

The MAC system starts with C5 being cleaved by _____.

C5 convertase

C5 is cleaved into _____ and _____.

C5a (smaller)
C5b (bigger)

Which is the more potent anaphylatoxin, C5a or C3a?

C5a (more potent and more stable)

Both C3a and C5a signal release of ____ and ____ cells.

mast cells

_____ starts the MAC by successive Binding of C6, C7, C8, & C9's (up to 16)


Pores created by MAC are _____ in diameter.

100 angstroms

_____ & _____ prevent recruitment of C9

HRF (Homologous Restriction Factor)
CD59 (Protectin)

What are defensins?

human antimicrobial peptides
(mostly defend against bacteria)

T/F Defensins are amphipathic peptides.

True (means they can move anywhere)

Where are defensins found?

gut, eyes, oral cavity, nose

What are the 2 types of defensins?


Defensins are secreted at _____ surfaces and also by ____ cells.

mucosal surfaces
PMN's (neutrophils)

(T/F) Defensins evolve slowly

(evolve rapidly in an arms race against bacteria)

What stem cell, in general, gives rise to INNATE immune cells?

Myeloid Stem Cells
(not all innate, also gives rise to RBC, platelets)

What stem cell, in general, gives rise to ADAPTIVE immune cells?

Lymphoid Stem Cells
(NK cells are considered innate)

(T/F) Mast cells are granulocytes


Are granulocytes fixed in one area or do they circulate?

circulate body looking for pathogens (part of INNATE)

Which cells are granulocytes?

neutrophils, eosinophils, basophils, & mast cells

______ contain granules with lytic enzymes and contain surface receptors for antibody AND complement.

PMN's (Polymorphonuclear Neutrophils)

______ are NON-phagocytic and are responsible for allergy and parasite response.


_____ are both fixed and circulating.


Phagocytes contain surface receptors that recognize ______.


What are PAMPs?

(Pathogen-Associated Molecular Patterns) used to recognize molecular patterns such as bacterial cell wall protein, LPS, & glycoproteins that are absent in humans.

What are Toll Like Receptors (TLR)?

Receptors that can recognize different DNA and RNA strands.

What are AMPs?

Anti-Microbial Peptides - peptides that form pores in microbial membranes causing cell death.

What are the 2 main types of AMP's?


(T/F) Amps are broad spectrum meaning low specificity.


_____ cells are star-shaped cells that migrate and are considered the "activators" turning other immune cells ON.

Dendritic cells

____ cells are considered the "bridge" between the innate and adaptive immune system bc they activate the adaptive immune cells.

Dendritic Cells

What are the Phagocytosis steps?

1. surface pathogen recognition
2. organism taken into phagosome
3. Lysosome fuse - phagolysosome
4. Oxidative enzymes cause a respiratory burst.
Reactive Nigtrogens work better on viruses and fungi as opposed to bacteria

What happens if you have weak barriers?

Epidermolysis bullosa - blister easy

What happens if you have NO negative regulation of the alternative complement pathway?

Immunodeficiencies - bc system remains at a heightened response so it does not recognize when there is an actual pathogen.

What happens if the MAC complex forms pores in self-cells?

Lysis of cells - kills RBC and host of other problems

What would happen if phagocytes do not recognize or kill foreign objects?

Chronic and recurrent infections