6/27 - Diseases of Immune System Flashcards
what type of organs are tissues of the immune system
generative and peripheral organs
what are generative organs
thymus and bone marrow
what are the peripheral organs
lymph nodes, spleen, mucosal tissues, and cutaneous lymphoid tissues
what is the function of MHC molecules
to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells
! T/F: MHC are proteins and its lower most unit are molecules
TRUE
Is T-cell recognition of antigens MHC restricted?
YES
how are MHCs deleterious to the pathogen
- virus-infected cells are killed
- macrophages are activated (to kill bacteria in their intracellular vesicles)
- B cells are activated (to produce antibodies that eliminate or neutralize extracellular pathogens)
T/F: even if a pathogen has mutated, it DOES NOT escape presentation by an MHC molecule
FALSE! it does escape MHC presentation
what properties of MHC make it difficult for pathogens to evade immune responses (what makes it special)
- polygenic
- polymorphic
what does it mean for an MHC to contain several different MHC class I and MHC class II genes, so that every individual possesses a set of MHC molecules with different ranges of peptide-binding specifities
polygenic
what does it mean for an MHC to have multiple variants of each gene within the population
polymorphic
what are the most polymorphic genes known
MHC genes
when is the only time cell surface proteins/MHCs are identical?
identical twins
what contributes to the diversity of MHC molecules expressed by an individual
polymophism an polygeny
polymorphism of MHC molecules is a critical importance in antigen recognition by ___
T cells
T cell recognizes antigen as a peptide bound by a particular allelic variant of an MHC molecule and will not recognize the same peptide bound to other MHC molecules. What is this behavior of T cells called?
MHC restriction
MHC are located on what chromosome in humans
chromosome 6
how many genes are contained in MHC
more than 200
what are MHC called in humans
Human Leukocyte Antigen (HLA genes)
where are MHC class I molecules found
- cell surface of all nucleated cells in vertebrates
- platelets (no nucleus)
exception: red blood cells
where are MHC class II molecules found
on professional antigen-presenting cells important in initiating immune response
(e.g. dentritic cells, mononuclear phagocytes, some endothelial cells, thymic cells, and B cells)
because of polygeny of MHC, every person expresses ___ different antigen-presenting MHC class I molecules and ___ MHC class II molecuels on his or her cells
at least 3 MHC class I
3 (or sometimes 4) MHC class II
what is the clinical significance of MHC molecules
typically involved in tissue transplatation - donor/host pairs not perfectly matched at HLA locus resulting in graft rejection
advances in immunosuppression and improved ability to match donor and host at the genetic level have resulted in a survival rate of ___ of most solid organ grafts ___ years post-transplant
> 80%, 5 years
immune response interactions depend on what?
- cell-to-cell contact
- mediation by cytokines (secreted proteins)
what are cytokines that mediate interactions between leukocytes
interleukins
are interleukins soluble proteins
yes
what are responsible for controlling the harmful effects of inflammation and tissue-damaging immune reactions (TNF for RA)
inhibiting cytokine
majority of cytokines are ___ or ___. rarely are they ___
autocrine or paracrine
rarely endocrine
B!
what type of signal occurs on same cell, adjacent cell, and far away?
autocrine, paracrine, endocrine
examples of autocrine hormones/cell signals
growth factors and cytokines
examples of paracrine cell signals
hormones and neurotransmitters
examples of endocrine cell signals
hypothalamus, pituitary, thyroid, parathyroid, adrenal, pineal body, ovaries, testes
what principally produces cytokines of adaptive immunity
CD4+ T cells
what is the function of adaptive immunity cytokines
- promote lymphocyte proliferation and differentiation
- activate effector cells
what are the cytokines of adaptive immunity
IL-2,4,5,7,17
IFN-gamma
these are some but there are more
what is an abnormal tissue reaction causing tissue injury
hypersensitivity reactions
what is the basis of pathology associated with immunologic diseases
hypersensitivity reactions
what can elicit HS reactions
exogenous agents or endogenous self antigens
dust, pollen, foods, drugs, microbes and various chemicals are examples of what
exogenous agents
endogenous self antigens results in ___
autoimmunity
what do HS reactions usually result from
- imbalance between effector mechanism of immune responses
- control mechanisms that limit these responses
HS development is often associated with inheritance of what?
susceptibility genes
T/F: mechanism of tissue injury are NOT the same as the effector mechanism of defense against infectious agents
FALSE! they are the same!
what type of HS reactions are immune reactant/B cell and what type are cell mediated/T cells
I, II, + III = immune reactant
IV = cell mediated
what are Type I HS reactions mediated by
antibody IgE and Mast cell
what type of antigen for Type I HS
soluble antigen
examples of Type I HS
- allergic rhinitis
- asthma
- systemic anaphylaxis
explain Type I HS reaction
- IgE release of antibodies against soluble antigen
- results in mast cell degranulation
what are WBC that play an important role in immune systems response to certain bacterial and parasitic infections
mast cells
what do mast cells contain
mainly: histamine
also: cytokines, growth factors and heparin
where are a majority of mast cells located
skin, lungs, and GI
response to antigen in Type I HS occurs in what stages
- sensitization
- effect
what occurs during sensitization stage of type I HS
host experiences asymptomatic contact w/ antigen
what occurs during effect stage of type I HS reaction
pre-sensitized host is reintroduced to antigen which leads to type I reaction (anaphylactic or atopic diseases)
clinical syndrome:
anaphylaxis (drugs, food, bee sting)
what is the clinical and pathologic manifestation?
fall in BP (shock) caused by vascular dilation; airway obstruction due to laryngeal edema
clinical syndrome:
bronchial asthma
what is the clinical and pathologic manifestation?
airway obstruction cause by bronchial smooth ms. hyperactivity; inflammation and tissue injury cause by late-phase reaction
clinical syndrome:
allergic rhinitis, sinusitis (hay fever)
what is the clinical and pathologic manifestation?
increased mucus secretion; inflammation of upper airway, sinuses
clinical syndrome:
food allergies
what is the clinical and pathologic manifestation?
increases peristalsis due to contraction of intestinal muscles
