host responses exam 1 Flashcards
what is the sequence of host responses to implants
- injury
- exudation of blood - biomaterial interactions
- provisional matrix formation
- acute inflammation
- chronic inflammation
- granulation tissue formation
- foreign body reaction (FBR) OR regeneration/healing
what is exudation
a process where fluid, proteins, and blood cells escape from the vascular system into the inter-vascular space of the injured tissue
what is acute inflammation
tissue injury triggers release of chemical factors that attract neutrophils to the site of injury from the bloodstream
what is chronic inflammation
inflammatory phase with monocyte activation - monocytes convert to macrophages in injury site to determine the intensity of inflammation
when are foreign body reactions (FBR) induced
when macrophages can’t phagocytose macroscale biomaterials and then release agents to degrade teh material
what does granulation tissue for healing/regeneration involve
reorganization of tissue-wound healing process - fibroblasts produce new extracellular matrix to form connective tissue
what are foreign body giant cells (FBGCs)
multinucleated giant cells formed as a result of fusion of multiple macrophages during chronic inflammation
what does TNF-alpha do
signals more cells to come to the biomaterial
what can FBRs lead to
fibrous encapsulation - fibrous, non-vascularized, connective tissue walls off implants
what is dystrophic calcification FBR
deposition of poorly crystalline calcium phosphate in diseased cells in individuals with normal calcium metabolism (usually kills cells)
what is metastatic calcification
deposition of calcium phosphate in normal tissue in individuals with deranged mineral metabolism
what is pathological calcification
includes both dystrophic and metastatic calcification
what is physiological calcfication
normal formation of crystalline calcium - calcification is more active in younger individuals with implanted biomaterials
what are the differences between innate and adaptive immunity
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
what is the difference between M1 and M2 macrophages
M1: pro-inflammatory, drive connective tissue formation or scarring
M2: tissue remodeling, efficient wound healing, allergy responses, Th2 activation
what immune responses do non-cellular biomaterials/devices evoke
innate immune responses
what immune responses do cellular biomaterials/devices evoke and why
adaptive immune responses due to the difference in MHC I in cells of different individuals. pathogens can evoke adaptive immunity via MHC II
what is a dendritic cell
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
what are two subtypes of T cells
CD4+ (helper T cell) and CD8+ (toxic T-cell)
both work together to kill infected cells
what’s the difference between TH1 and TH2 helper T cells
TH1 is good for macrophages and TH2 are inhibitory to macrophages
what antigens are associated with MHC I and II
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
what are the inflammatory aspects of dead cells
self and non-self/auto necrosis (accidental cell death) is inflammatory
self is non for apoptosis and non-self is inflammatory for apoptosis
what are antibodies
proteins secreted by activated B lymphocytes (plasma cells) with specificity for specific antigens
what are cytokines
proteins secreted by cells including both immune and non-immune cells that regulate and coordinate the cellular response/signaling
what are growth factors
any naturally occurring substances (proteins or non-proteins like steroids and hormones) that affect cell growth/proliferation and differentiation
what are natural killer cells and how does MHC effect them
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
