Innate immune response

Question 1

Which strategies has pathogens evolved to avoid activation of the complement system

Answer 1

Mimic host cell surfaces and secrete proteins that inhibit components of components

Question 2

Complement activation pathways

Answer 2

Lectin pathway, classical pathway and alternativer pathway

Question 3

Lectin pathway

Answer 3

Triggered by the pattern-recognition receptors MBL and ficolins - that bind to particular carbohydrate structures on microbial surfaces

Question 4

Classical pathway

Answer 4

Triggered when C1 recognizes a microbial surface directly or binds to antibodies already bound to a pathogen

Question 5

Alternative pathway

Answer 5

Utilizes spontanous C3 deposition onto microbial surfaces, it is augmented by properdin and amplification loop for the two other pathways.

Question 6

Complement activation

Answer 6

accumulation of C3b on microbial membranes, which is recognized by complement receptors on phagocytic cells to promote microbial clearance by cells recruited to sites infected by C3a and C5a

Question 7

C3b

Answer 7

Formed by a C3 convertase enzyme, which cleaves C3 to produce cleavage product C3b.

Question 8

Complement-regulatory proteins

Answer 8

interact with C3b and either prevent the convertase forming or promote its rapid dissociation

Question 9

Opsonization

Answer 9

Refers to coating a pathogen with antibodies and/or complement proteins, which leads to phagocytosis by phagocytic cell

Question 10

Zymogens

Answer 10

pro-enzymes that become active only after proteolytic cleavage

Question 11

Immune response

Answer 11

beginning with immediate innate defenses, then induced innate defenses and finally adaptive immunity

Question 12

Inflammatory response

Answer 12

recruits effector cells and molecules of the innate immune system in tissue from blood, while clotting small blood vessels downstream to prevent spread of microbe.

Question 13

Defensins

Answer 13

Peptide that disrupt cell membranes of bacteria and fungi, as well as membrane envelopes of some viruses, present epithelial cells and neutophils

Question 14

Cathelicidins

Answer 14

Peptide is activated by proteolytic cleavage, by neutrophil elastase, and is a cationic amphipathic plasmide that disrupts membranes and is toxic to many microorganisms, present in neutrophils

Question 15

Histatins

Answer 15

Cationic peptides that are active agianst pathogenic fungi and promote rapid wound healing, present in the oral cavity

Question 16

Lymphoid tissues

Answer 16

B cell, T call, NK cells, mature dendritic cell and innate lymphoid cells

Question 17

Myeloid lineage

Answer 17

Immature dendritic cell, mast cell and macrophage

Question 18

Macrophage

Answer 18

perform different functions in innate immune response and adaptive immune response, one is to engulf and kill microorganisms. present in almost all tissues

Question 19

Granulocytes

Answer 19

consists of neutrophils, eosinophils and basophils. They take up microorganisms by phagocytosis and destroy them with substances stored in vesicles. The later two acts on parasites, which are to big for neutrophils and macrophages

Question 20

Mast cells

Answer 20

Consists of granules, that contain inflammaotry mediators and protect the internal surfaces from pathogens

Question 21

Dendritic cells

Answer 21

Take up particular matter by phagocytosis and also continually ingest large amounts of the extracellular fluid and its contents by macropinocytosis

Question 22

Pattern-recognition receptors (PRRs)

Answer 22

recognize simple molecules and regular patterns (PAMPs)

Question 23

Cytokines

Answer 23

protein secreted by immune cells that effect the behavior of nearby cells

Question 24

Chemokines

Answer 24

secreted proteins that act as chemoaatractants, attracting cells bearing chemokine receptors, as neutrophils and monocytes

Question 25

Common lymphoid progenitor

Answer 25

Gives rise to antigen-specific lymphocytes of the adaptive immune system and innate lineages that lack antigen-specifik receptors

Question 26

pathogen-associated molecular patterns (PAMPs)

Answer 26

molecules and regular patterns of molecular structure that are part of microorganisms, but not that of the hosts.

Question 27

toll-like receptors (TLRs)

Answer 27

transmembrane proteins, that detect PAMPs derived from extracellular bacteria or bacteria taken into vesicular pathways by phagocytosis

Question 28

NOD-like receptors (NLRs)

Answer 28

Cytoplasmic proteins, that sense intracellular bacterial invasion.

Question 29

Tissue damage by pathogens

Answer 29

Exotoxin production, endotoxin, direct cytophatic effect (direct) and immune complex, anti-host antibody, cell-mediated immunity (indirect)

Question 30

T-cells

Answer 30

lymphocytes that express distinct types of antigen receptors, and has a T-cell antigen receptor. When an antigen binds to the receptor the Tcell proliferates and differentiates into several different functional effector T-cells

Question 31

B-cells

Answer 31

Lymphocytes that expres distinct types of antigen recptors, and B-cell antigen receptor. When an antigen binds to the BCR, the B-cell proliferates and differentiates into plasma cells

Question 32

NK-cells

Answer 32

Natural killer cells are larger than T- and B-cells, have distinctive cytoplasmic granules containing cytotoxic proteins. Receptors on NK-cells detect changes in expression of various surface proteins on target cells (malignant transformation).

Question 33

Scavenger receptors

Answer 33

phagocytic pattern-recognition receptors that recognize various anionic polymers and acetylated low-density lipoproteins.

Question 34

Complement receptors

Answer 34

Complement receptors are GPCRs that are expressed on several immune cell types and are activated by complement protein fragments that are generated in the plasma during an acute inflammatory response

Question 35

Oxidative bursts

Answer 35

The rapid release of reactive oxygen species (superoxide anion and hydrogen peroxide) from different types of cells

Question 36

Extravasate

Answer 36

The attachment and thereafter migration of leukocytes into the tissues.

Question 37

TLRs

Answer 37

Toll-like receptors activates innate and adaptive immune responses and reside in membrane and senses microbes present in extracellular spaces and endosomes

Question 38

NODs

Answer 38

Nucleotide-binding and oligomerization domain are subfamily of Nod-like receptors, and sense the presence of bacteria by recognizing bacterial peptidoglycans and ssRNA to activate NFkB to induce expression of pro-inflammatory genes

Question 39

Autokrine action

Answer 39

cytokines affecting behavior of the cell that releases the cytokine

Question 40

Parakrine action

Answer 40

cytokines affecting adjacent cells

Question 41

Endokrine action

Answer 41

cytokines affecting distant cells, depends on their ability to enter circulation and half-life in blood

Question 42

JAK-STAT pathway

Answer 42

chain of interactions between proteins in a cell, involved in processes such as immunity, cell division, cell death, and tumour formation. The pathway communicates information from chemical signals outside of a cell to nucleus leading to transcription activating genes. Janus kinases (JAKs), signal transducer and activator of transcription proteins (STATs), and receptors (which bind the chemical signals)

Question 43

TNF receptors

Answer 43

Transmembrane proteins, some can be released into the from the membrane. Contains more than 17 cytokines with important functions in adaptive and innate immunity.

Question 44

Selectins

Answer 44

membrane glycoproteins with distal lectin-like domain that bind carbohydrates to mediate the adhesion of leukocytes to endothelial cells and platelets under flow.

Question 45

Immunuglobin superfamily

Answer 45

protein domains similar to those of immunoglubins and have various roles in cell adhesion. (ligand for integrins).

Question 46

Integrins

Answer 46

Heterodimeric proteins that bind to cell-adhesion molecules and extracellular matrix (strong adhesion).

Question 47

IFIT proteins

Answer 47

IFN-induced protein with tetratricoid repeats that function in restraining translation of viral RNA into proteins (antiviral effector).

Question 48

ILCs

Answer 48

Innate lymphoid cells function in innate immunity as effector cells that amplify signals delivered by innate recognition. reside in lymphoid tissues and peripheral organs.

Question 49

ITIM

Answer 49

Immunoreceptor tyrosine-based inhibition motif. Inhibitory KIRs and Ly49s (activating and inhibitory receptors) contain tail containing ITIM, when ligand associate with recptors ITIM phosphorylated.
- inhibits by removing phosphates from tyrosine residues on other intracellular signaling molecules
- activates by activating intracellular signaling pathways

Question 50

ITAM

Answer 50

immunoreceptor tyrosine-based activation motif (ITAM) is a highly conserved region in the cytoplasmic domain of signaling chains of adapter proteins and receptors and is a critical mediator of intracellular signals. required for the differentiation and function of B and T cells in adaptive immunity and regulates the function of innate immune cells, natural killer cells and myeloid cells

Question 51

NLRs

Answer 51

Nod-like receptors possesses additional domains that result in diverse functions and, in some instances, enable detection of infection. Eg. initiation of inflammatory responses, cell death and release of different pro-inflammatory cytokines.

Question 52

Autophagy

Answer 52

housekeeping role in removing misfolded or aggregated proteins, clearing damaged organelles, such as mitochondria, endoplasmic reticulum and peroxisomes, as well as eliminating intracellular pathogens. This is done by engulfing and fusion of lysosomes to create an autolysosome.