Intro to Host Defense Flashcards
What are the characteristics of innate immunity?
Pre-formed Non-specific No Memory Does not improve over time
What are the 3 components of innate immunity?
Barriers Cells Antimicrobial Peptides and complement
What are the 5 cells of innate defense?
Neutrophils Monocytes Macrophages Dendritic Cells (DC) Natural Killer Cells (NKC)
Which cells of the innate defense are non-phagocytic?
Natural Killer Cells
What are the characteristics of adaptive immunity?
Slow Onset Highly effective once active Highly specific Memory Improves over time
What are the two components of adaptive immunity?
B lymphocytes T lymphocytes
Where do B lymphocytes differentiate?
The bone marrow
What do B cells produce?
Antibodies or immunoglobulin
Where do T cells differentiate?
In the thymus
What do T cells produce?
Cytokines of interleukin
What does lysozyme degrade?
Peptidoglycans
How does skin secrete lysozyme?
Through the sweat glands
What are macrophages?
Differentiated forms of monocytes present in the tissues
What is this cell?
A Neutrophil
What is this cell?
A monocyte
What is a DC capable of?
Phagocytosis and pinocytosis
What do DCs and macrophages present on their cell surface?
A unique protein antigen called a CD14
Are DC’s the most efficient antigen presenting cells?
Why yes they are.
How do macrophages and DC’s participate in innate immunity once they phagocytose a microbe?
They destroy the microbes and secrete cytokines
How do macrophages and DC’s participate in acquired immunity after phagocytosing a microbe?
They present antigens to CD4-positive helper T cells
What fuses during intracellular killing of phagocytosed microbes?
The phagosome containing the microbe with the lysosome
What is generated as a result of intracellular killing of phagocytosed microbes?
Reactive nitroge intermediates
Antimicrobial peptides
Reactive oxygen intermediates
What does lactoferrin do?
Sequesters iron
What are defensins?
Cationic peptides
What are alpha-defensins produced by?
Neutrophils and Paneth cells of the stomach
What produces beta-defensins?
Epithelial cells in the respiratory tract
What are some antimicrobial peptides?
Defensins
Lysozyme
Lactoferrin
The presence of what 3 things can activate complement?
Infection with gram neg bacteria causing release of LPS
Infection with fungal or gram pos bacteria causing release of mannose
Ag-Ab reactions
What components are required for the classical pathway of complement activation?
Ag-Ab complex + C1, C4 and C2 complex
What components are required for the alternative pathway for complement activation to start?
Microorganisms’ cell wall polysaccharides + Factor B, Factor D and Factor P
What do the classical pathway and alternative pathway bring in once started?
C3 which starts the formation of the MAC complex, causes inflammation as well as opsonization?
What for of C3 causes opsonization?
C3b
What do C3a and C5a cause?
Inflammation
What is opsonization?
Coating of the bacterial surface which enhances phagocytosis
What components form the MAC complex?
C3b
C5b
C6
C7
C8
C9
How does the MAC complex result in cell lyses?
It inserts itself into the target cell membrane and creates a hole
What do NK cells attack and how?
They attack virus-infected body cells by causing the cells to burst by releasing perforin and granulysin
What induces NK cells to lyse target cells?
The down regulation of MHC class I
What does TLR4 recognize?
LPS
What does TLR2 recognize?
Peptidoglycan
What 3 steps happen in T cell response?
Antigen recognition
Activation
Response
What do antigens contain?
One or more antigenic determinants also known as epitopes
How are haptens different from epitopes?
They are too small to start an inflammatory response
What do all T lymphocytes express?
The CD3 antigen
In addition to CD3 what doe Cytotoxic T cells express?
CD 8
In addition to CD3 what do Helper T cell express?
CD 4
What MHC complex do cytotoxic T cells recognize?
MHC I which is a closed ended structure that accomodates peptides of 8-9 amino acids
What MHC complex do helper T cells recognize?
MHC II which is an open ended structure that accomodates peptides of 18-20 amino acids.
What is IL-4-B
A cell growth factor
What is IL-5-B?
A cell differentiation factor
What are the 5 classes of antibodies?
IgM, IgG, IgE, IgA, IgD
What is IgM?
A pentamer
What can IgG travel through?
The placenta
What does IgE participate in
Allergic reactions
What is IgA secreted in?
Tears and colostrum
What is IgD?
A B cell receptor
What is LPS considered?
A T-cell independent antigen
How do B cells respond to T-cell independent antigens?
They differentiate into plasma cells which releases the IgM antibody
What are T cell dependent antigens?
Proteins
How do B cells respond to T-cell dependent antigens?
They go through class switching
Where is IgG derived from in perinatal development?
The mother
Where is IgA derived from in the infant stage?
Mother’s milk
Do newborns respond well to proteins antigens?
Yes
Do elderly people have weak or strong immune systems?
Weak with weak tolerance to self antigens
