Innate Immuno Flashcards
What is the role/purpose of the immune system?
- Protect from pathogens
- Inflammation
- Eliminate modified or altered self
What are mechanisms of protection?
Mechanical, Cellular, Humoral
What are the major differences between innate and adaptive immunity?
Innate- no time lag, not Ag specific, no memory
Adaptive- lag period, Ag specific, development of memory
Which cells comprise the innate immune system?
Myeloid cells:
Granulocytic cells, including neutrophila, basophila, eosinophila, and mast cells
Monocytic- macrophages, Kupffer cells (MO in liver), dendritic cells
Which humoral components comprise the innate immune sytem?
Complement and interferon
What are the other main components of innate defense?
Anatomic barriers, including skin, mucosal membranes (gut and bronchial)
Psychologic barriers, including temperature, fever, basic pH (stomach, skin, vagina), and enzymes
What is the purpose of neutrophils/ PMN?
Attack first- phagocytes. Activated by cytokines and respond rapidly to chemotactic stimuli
Express Fc so involved in opsonization for phagocytosis
what is the purpose of macrophages?
- Slower than neutrophils but are larger, live longer. -Found in all organs and connective tissues
- Produces cytokines to recruit other inflammatory cells and systemic effects like fever
- APC to Tcell
What is Chronic Granulomatous Disease?
What is the treatment?
- defect in NADPH oxidase system=cannot form ROS….leads to recurrent infections w/ Staph aureus, salmonella, pseudomonas, and fungi
- education and preventive antibiotics
What is the role of NO?
Helps MO in killing intracellular pathogens Vasodilation (drop of bp in sepsis)
What is the role of dendritic cells?
sample environment- phagocytize Ag and then migrate to lymph nodes as APC to activate Tcells
What is the role of a mast cell?
Bone marrow derived, found in most tissue by blood vessels. Role in inflammation and allergies (with IgE).
What is the role of basophils/eosinophils?
Parasitic infections (by using enzymes for tissue damage) and allergies
What is the role of interferons?
Stimulate cells to turn on genes for antiviral proteins
Why does complement system not attack host cells?
Host cells have proteins that deactivate complement cascade such as DAF and MCP to deactivate C3b and CD59 to deactivate MAC
Which cells are involved in adaptive immunity?
Lymphocytes- T cells (Helper, suppressor, cytotoxic), B cells (plasma cells), NK cells
What are the key features of an adaptive response?
Specificity, diversity, memory, self-regulation, discrimination of self from non-self
What are Antibodies composed of?
How many classes of Ab?
Two light and Two heavy chains, with a constant site and variable site where the Ag binds.
Also, constant region is Fc receptor
5- IgG, IgM, IgA, IgD, and IgE
IgG
G: 80% in serum, Neonatal immunity (binds to macrophage and neutrophils via FcR)
viral infections
Describe how the binding of Ab inactivates Ag.
Neutrilization, Aggultination, Precipitation, Complement fixation—> enhanced phagocytosis
or cell lysis (MAC)
What is the life cycle of a MO?
Made in bone marrow–> monocyte in blood–> tissues MO becomes either (1) activated or (2) microglia, kupffer cell, alveolar MO, or osteoclast
The 3 pathways for complement all result in what?
Lectin, classical, and alternative pathways generate C3a–>
C3a and C5a release histamine, chemotactic and increase vascular permeability
C3b opsonin
MAC
What is a major difference between B and T cells in terms of Ag recognition?
T cell recognizes small fragment= MHC bound Ag
B cell recognizes larger fragment
What is an important feature regarding the type of Ab a single mature B cell is capable of making?
Clonal, which means only 1 type of Ab
IgM
M: 13% of serum, First Ab produced, pentameter (can bind up to 5 Ag for opsonization)
IgA
A: 6% serum, dimer and secretory component (saliva, tears, colostrum, milk)
IgD
D0.2% serum, BcellR, may play role in eliminating self-reactive Ab
IgE
Why is second exposure to allergen worse than 1st?
E:0.002% of serum Ab because tightly bound to basophils and mast cells (via Fc region)
Parasites and allergic rxns
?: IgE begins binding to mast cell after 1st so by 2nd, its already bound so quicker response
How is it possible to generate so many different variable regions of Ab?
Somatic recombination- happens at DNA level before transcription AND different combining of light and heavy chains AND mutation
What is ADCC?
Ab dependent cell-mediated cytotoxicity… Ab opsonize virus-infected cell, connect to NK/cytotoxic Tcell–> which release granuoles to kill cell
What happens to an immature B cell in the bone marrow if it matches up with Ag?
It would only match with self cells to it would need to be destroyed
How does a mature B cell differ from activated B cell and memory B cell?
Mature B cells will die if they don’t encounter Ag outside of bone marrow.
Activated B cell has matched up with Ag and will proliferate more Ig to be secreted (rather than on membrane)–>plasma cell
Memory B cells remain with membrane Ig which may be stimulated to secondary Ab response
How does a B cell become activated to produce Ab?
Engulfs Ag–> binds to MHC–> presents combo+CD40 to T cell CD40L–> B cell proliferate to class switch Ig and become plasma cells
What is XLA?
Don’t generate mature B cells so susceptible to bacterial and some viral infections but not intracellular microbes and fungi (uses NK and MO)
What is hyper IgM syndrome?
defect in class switch due to CD40L being defective so only have IgM present with persistent bacterial infections and neutropina (and MO deficiency) b/c CD40 important for granulocyte development too
What is MHC/HLA? What does it have to do with tissue type?
It is the Major Histocompatibility Complex. Co-dominantly expressed and it is part of the way Tcells distinguish self from non-self
What are the distinct characteristics of MHC I?
Expressed on all nucleated cells
Presents endogenously synthesized Ag (virus in as its passing though ER to be synthesized)
Checked by killer T cells (CD8)
What are the distinct characteristics of MHC II?
Expressed on B lymphocytes, MO, dendritic cells, and endothelial cells ( may be induced by cytokines though)
Presents exogenous Ag proteins (bacterial proteins in vesicles)
Checked by Helper T cells (CD$)
What role does MHC play in Graft v Host and Host v Graft?
Graft v Host: ex bone marrow= donor immune cells attack host cells
Host v Graft: ex kidney transplant= host immune cells attack donated tissue
How do the different Ig differ in structure?
Fc receptor region on the heavy chains in response to certain cytokines
