Lecture 15 Flashcards
(28 cards)
What causes immunodeficiency?
Genetic factors — deletion of mutations of a certain immune system gene
External factors like HIV
What is severe combined immunodeficieny?
What function is missing?
Failure of antibody and TCR gene rearrangement during T and B cell development
Lack of mature T and B cells — no adaptive immune response
Deficiency of what chain causes SCID? (in T cells)
functional & outcome?
Developmental defect:
No thymus, defect RAG1/2, lack of MHC
Deficiency of gamma chain on X chromosome causes SCID
Functional affect:
Gamma is subunit for many cytokine receptors
Gamme interacts w/ Jak3 kinase to mediate signaling
Gamma is needed for many different cytokines recerptors for signaling, like IL7 and IL4
outcome:
no T cell devlepoemt – lack Il7
B cells get no help due to defective Il4
what is the major difference between SCID and acquired immunodeficieny syndrome?
SCID stems from a genetic factor—- patient is born with the disease
AIDS is acquired after birth, where the immune cells are depleted
What are the possible outcomes of selective B & T cell deficiency?
Can lead to recurrent bacterial infection
T cell: can be fatal or lead to inflammation
How might selective B cell deficiency occur during B cell maturation?
earlier Lead to lack of Ig,
where as later defects can lead to hyper Ig-M syndrome or absences of single isotope
What is hypersensitivity, allergy, and autoimmunity ?
How do they differ and what is the common factor?
Hypersensitivity: inappropriate response to non pathogen
Allegery: hypersensitivity to exogenous antigen
Autoimmunity: hypersensitive to self antigen & produced antibodies directed against self antigens
- failure of host humoral & cellular immune to distinguish from non self ( failure of tolerance)
What is the main difference between type 1 and type 4 hypersensitivity ?
Type 1: IGĘ mediated immediate response
- IgE activates mast cells, which start allergic reactions by releasing effector molecules like HISTAMINe and by recruiting other immune cells
Type 4: Th1 cell mediated delayed response
Sensitivity of antigens activates dendritic cells presenting antigens to Th1 cells
Activated Th1 cells secrete IFN gamma + CD40L, which activates macrophages— release product that damage tissue
What are predispong conditions that may lead to autoimmune disease?
MHC halotypes are associated wit higher risk of some autoimmune disease
Infectious agents that can increase inflammation or react with host antigens , genetic susceptibility, environmental influences (lack or early exposure to diseases)
What is the major diff between systemic and organ specific autoimmunity?
Target
- systemic targets many organs w/ body due to antigens shared among these organs
-ex: RA, lupus - organ—-targeted to antigens from one specific organ
-type 1 diabetes
-
What is host vs graft disease and graft vs host?
Host vs graft: solid organ transplanted, recipient Tcell attack the transplant, leading to rejection
-immune response to non self MHC
Graft vs host: bone marrow is transplanted, T cells attack the recipient tissue
What are the most common types of innate immune deficiency & what is the outcome?
Defienciesin phagocyte function are the more common innate
Result in chronic inflammation
What is immune dysregulation?
Failure of host defense mechanism
Avoid and of normal host immune response by pathogen
Immunodeficieny
What causes immune avoidance?
Alter of antigens phenotype is how pathogens avoid humoral immunity
Symptoms: what is a possible immune defect of these?
Susceptible to bacteria
Suspecting to virus infection
Susceptible in general
B cells, complement components, phagocytes
CD8 T cell
NK cells
B and T cells
What is humoral immunodeficieny? (in B cell)
What are the develpmental and function defects?
Defect in RaG1/2– omenns
XLA— no Ig
Functional:
X linked hyper IgM syndrome—Cd40L ( on T cell)
Selective IgA deficiency
What is X linked hyper IgM syndrome? (B cell)
Mechanism? Outcome?
gene : Defective Cd40 ligand on X chromosome
CD40 ligand is expressed a lot on APCs
CD40L expressed by Th cells
CD40L on CD4 T cells interacts with Cd40 on B cells — activates B cells isotope switching
outcome
Lack of T cell to help activate B— no isotope switching
Normal or increased IgM, low IgG, IgA, IgE
How does HIV enter the cell ?
How does medication clear virus from blood?
CD4 and CXCR4/ CCR5
Blocks the viral life cycle and those In the blood will be rapidly clear
What initially controls HIV ?
What are the stages?
What happens when the virus replicates ?
CD8 initially controls is
Quiescent ( latency)
CD4 T cell declines , when below a threshold, < 200 per ml blood
Infected memory cells are capable of producing virus upon reactivation
For antibody mediated allergic diseases ( hypersensitive) , what are type 1, 2, and 3?
IgE and IgE mediated— allergic diseases:
IgE Antibody— allergy, anaphylaxis
Non IgE mediated—autoimmune:
Type 2: IgG/M bind to tissue & activate response — anemia, thyroiditis
Type 3: antigen-antibody complexes— lupus
What are T cell mediated allergic reactions (hypersensitivity)?
What is it caused by?
Type 4: cellular immune response
- delayed type hypersensitivity
Posion ivy
Injury caused by Th1mediated response, require repeated antigen interaction
Sensitization involves ___ to IgE production, which chain switches?
What cells make the reactions?
What controls the response?
Class switching of the heavy chain to IgE on first contact with allergen
Mast cells
Reg Tcells
Systemic autoimmune:
What are rheumatoid factors?
What is RA caused by?
What causes ŚLE?
Circulating IgG or IgM
Autoreactive Th17 or Th1 T cells interacts
Autoantibodies to persist at nuclear antigen— immune complexes continue to form
Organ specific diseases
What causes MS?
Myasthenia gravis?
Auto reactive T cell mediated — demyleinaton of T cells
Blocks Acetycholine receptors
