host responses exam 1

Question 1

what is the sequence of host responses to implants

Answer 1

1. injury
2. exudation of blood - biomaterial interactions
3. provisional matrix formation
4. acute inflammation
5. chronic inflammation
6. granulation tissue formation
7. foreign body reaction (FBR) OR regeneration/healing

Question 2

what is exudation

Answer 2

a process where fluid, proteins, and blood cells escape from the vascular system into the inter-vascular space of the injured tissue

Question 3

what is acute inflammation

Answer 3

tissue injury triggers release of chemical factors that attract neutrophils to the site of injury from the bloodstream

Question 4

what is chronic inflammation

Answer 4

inflammatory phase with monocyte activation - monocytes convert to macrophages in injury site to determine the intensity of inflammation

Question 5

when are foreign body reactions (FBR) induced

Answer 5

when macrophages can’t phagocytose macroscale biomaterials and then release agents to degrade teh material

Question 6

what does granulation tissue for healing/regeneration involve

Answer 6

reorganization of tissue-wound healing process - fibroblasts produce new extracellular matrix to form connective tissue

Question 7

what are foreign body giant cells (FBGCs)

Answer 7

multinucleated giant cells formed as a result of fusion of multiple macrophages during chronic inflammation

Question 8

what does TNF-alpha do

Answer 8

signals more cells to come to the biomaterial

Question 9

what can FBRs lead to

Answer 9

fibrous encapsulation - fibrous, non-vascularized, connective tissue walls off implants

Question 10

what is dystrophic calcification FBR

Answer 10

deposition of poorly crystalline calcium phosphate in diseased cells in individuals with normal calcium metabolism (usually kills cells)

Question 11

what is metastatic calcification

Answer 11

deposition of calcium phosphate in normal tissue in individuals with deranged mineral metabolism

Question 12

what is pathological calcification

Answer 12

includes both dystrophic and metastatic calcification

Question 13

what is physiological calcfication

Answer 13

normal formation of crystalline calcium - calcification is more active in younger individuals with implanted biomaterials

Question 14

what are the differences between innate and adaptive immunity

Answer 14

major classes of cells- phagocytes, NK cells in innate; B and T lymphocytes in adaptive immunity
time required to mount response - 0-12 hours in innate; 1 week in adaptive
adaptive has specificity of response and capacity for memory

Question 15

what is the difference between M1 and M2 macrophages

Answer 15

M1: pro-inflammatory, drive connective tissue formation or scarring
M2: tissue remodeling, efficient wound healing, allergy responses, Th2 activation

Question 16

what immune responses do non-cellular biomaterials/devices evoke

Answer 16

innate immune responses

Question 17

what immune responses do cellular biomaterials/devices evoke and why

Answer 17

adaptive immune responses due to the difference in MHC I in cells of different individuals. pathogens can evoke adaptive immunity via MHC II

Question 18

what is a dendritic cell

Answer 18

a type of leukocyte that is the linker between innate and adaptive immunity - they become MHC II expressing once mature, which is essential for antigen-specific adaptive immune response to kick in

Question 19

what are two subtypes of T cells

Answer 19

CD4+ (helper T cell) and CD8+ (toxic T-cell)
both work together to kill infected cells

Question 20

what’s the difference between TH1 and TH2 helper T cells

Answer 20

TH1 is good for macrophages and TH2 are inhibitory to macrophages

Question 21

what antigens are associated with MHC I and II

Answer 21

presentation of extracellular antigen to helper T cells - MHC II
presentation of cytosolic antigen cytolytic T lymphocytes - MHC I

elicit helper and cytosolic T-cell activation and B-cell antibody production

Question 22

what are the inflammatory aspects of dead cells

Answer 22

self and non-self/auto necrosis (accidental cell death) is inflammatory
self is non for apoptosis and non-self is inflammatory for apoptosis

Question 23

what are antibodies

Answer 23

proteins secreted by activated B lymphocytes (plasma cells) with specificity for specific antigens

Question 24

what are cytokines

Answer 24

proteins secreted by cells including both immune and non-immune cells that regulate and coordinate the cellular response/signaling

Question 25

what are growth factors

Answer 25

any naturally occurring substances (proteins or non-proteins like steroids and hormones) that affect cell growth/proliferation and differentiation

Question 26

what are natural killer cells and how does MHC effect them

Answer 26

kill cells without prior activation signaling - can be switched on or off depending on MHC expression

when cells get sick they express MHC I on the surface so natural killer cells can kill them