Immunopathology Type 4, Immune Regulation Flashcards
Where do dendritic cells present antigen?
in the lymph nodes
One activated Th1 cell can attract ____ macs.
1000
What is the frequency of abacavir hypersensitivity syndrome and what do we do bc of this?
8% of recipients; test for allele before giving drug (personalized medicine)
What is the first set reaction?
rejection in 10-20 days; 5-10% of T cells react to the foreign MHC
What are the s/s of Acute GvHD?
maculopapular skin rash, diarrhea, hepatic inflammation, jaundice, infections
What prevents Acute GvHD?
removing T cells from the bone marrow
What is a hyperacute/white graft reaction?
rejection before the graft even heals in- remains white and bloodless- from putting same graft in multiple times- due to Abs and histocompatibility antigens
What is the initiation of an immune response?
first exposure- immunization phase
HLA-B*1502 is assoc. with _____.
drug-induced hypersensitivity by carbamazepine
What is the HLA assoc. in T1D?
HLA-DR3 and HLA-DR4
What is Acute GvHD?
bone marrow rejection 2-10 weeks post transplant
Why doesn’t the graft usually win when it tries to reject the host? When does the graft actually win?
it’s smaller than the host, which overcomes it; immunocompetent host
What happens to cause T1D?
antibodies to beta-cells
What does a Th1 activation by M. leprae cause?
tuberculoid leprosy with large skin and nerve lesions, but they contain the infection
What is the assoc. allele in carbamazepine hypersensitivity?
HLA-B*1502
What is a xenograft?
from another species
What does Chronic GvHD sometimes cause?
autoimmunity
What is the treatment for contact dermatitis?
avoidance, topical steroids
Why does a graft-vs-host reaction occur?
graft contains T cells that, when transplanted, recognize the HLA on the recipient as foreign- the graft tries to reject the hose
What does a Th1 activation by M. leprae cause?
tuberculoid leprosy with large skin and nerve lesions, but they contain the infection
What is delayed-type hypersensitivity (DTH)?
T-cell mediated events that are undesirable or injurious
What genes are thought to be the problem in T1D?
DQ genes
What is the treatment for Acute GvHD?
anti-inflammatories; corticosteroids; immunosuppressives
What is MS?
demyelinating disease- T cell reactivity to autoantigen
Who does the dendritic cell present its MHC+antigen to?
Th0 precursors
What are treatments for MS?
- natalizumab (humanized monoclonal Ab) 2. rituximab (monoclonal Ab to B cells)
What are the characteristics of memory T cells?
more numerous in exposed person; lower activation threshold
What recognizes HLA-B5701 and why?
Th1 bc it’s a class I MHC
What is Hashimoto Thyroiditis?
destructive attack of the thyroid by T cells; most common cause of hypothyroidism
There are 9 examples of pathologies where Type IV is the causative mechanism. List?
- rejection of allographs 2. graft-vs-host disease 3. positive Tb test 4. resistance to Myco. tb 5. resistance to fungal infections 6. contact dermatitis (poison ivy) 7. chronic beryllium disease 8. autoimmune diseases (MS) 9.tumor immunity
The brain is ____ but not _____.
antigenic; immunogenic
What is the Mantoux skin test?
Tb skin test used in the US- uses 0.1ml of PPD injected intradermally
What is the second set reaction?
rejection of another graft in same patient- 5-10 days- due to T cell memory to first graft
How does QuantiFERON TB gold work?
M. Tb proteins are added to pt’s whole blood sample- incubate- measure IFN-gamma with ELISA
Th2 cells activate ____, which in turn produce ____ and attract _____.
M2 macs; fibrosis; eos
What is the only type of immunopathology that doesn’t require B cells or antibodies?
type IV
If the Mantoux skin test is positive, what is visible?
a 15mm or more raised induration
What do abacavir hypersensitivity syndrome patients have in common?
HLA-B5701
What is molecular mimicry?
viral peptides with very similar sequences and structures to MPB can illicit T-cell responses
What is the antigen in poison ivy?
oil of Toxicodendron radicans that contains urushiol
The brain is ____ but not _____.
antigenic; immunogenic
Why doesn’t the graft usually win when it tries to reject the host? When does the graft actually win?
it’s smaller than the host, which overcomes it; immunocompetent host
What does Acute GvHD stand for?
acute graft vs host disease
What is the elicitation phase?
reaction by already immunized person- effector phase
The strongest assoc. btw. HLA alleles and drug-induced hypersensitivity is in carbamazepine and the _____.
Han Chinese
What is the only routine T-cell mediated immunity test?
QuantiFERON-TB gold
What do Th0 precursors differentiate into and why?
Th1 ad Th17 cells; they were activated by antigen-presenting cells
What disease has molecular mimicry been implicated in?
MS
What does a Th2 activation by M. leprae cause?
widely disseminated infection into small granulomas (lepromatous leprosy)
Why is there typically no reaction in the initiation phase?
by the time the T cells have divided and are circulating, the antigen is gone
What is Sjogren Syndrome?
autoimmune rxn to exocrine glands, esp tears and saliva
Why aren’t Tb tests immunizing?
they use too small of a dose
What does Chronic GvHD stand for?
chronic graft vs host disease
When does the inflammation become visible in the elicitation phase? When does it peak?
6-12 hours; 24-48 hours
What is abacavir hypersensitivity syndrome?
type IV rxn to abacavir
Why is QuantiFERON-TB gold used?
to check for Tb in pts that have received the Tb immunization shot, BCG- it doesn’t cross react with BCG
What genes are thought to be the problem in T1D?
DQ genes
What is the treatment for Acute GvHD?
anti-inflammatories; corticosteroids; immunosuppressives
When is a Mantoux skin test read?
48 hours later
What does breakdown of the skin lead to?
blistering
What does DTH stand for?
delayed type hypersensitivity
The strongest assoc. btw. HLA alleles and drug-induced hypersensitivity is in _____ and the Han Chinese.
carbamazepine
What is within the induration?
a cellular infiltrate
What disease has molecular mimicry been implicated in?
MS
Th2 cells are found in the periphery of inflammatory and infectious states, especially ____ and ____.
asthma; chronic worm infestation
What is Graft-vs-Leukemia reaction?
bone marrow transplant recipients have a high rate of leukemia when T cells are depleted
What is the HLA assoc. in T1D?
HLA-DR3 and HLA-DR4
What is carbamazepine?
drug used to treat sz, nerve pain, bipolar disorder
What does M. leprae do to DCs?
cause them to activate either Th1 or Th2, which each have different pathologies
What happens during the elicitation phase?
memory T cells are activated by initial antigen reappearance; secrete interferon-gamma to attract macs- inflammation
What is the causative organism of Leprosy?
Mycobacterium leprae
What is Hashimoto Thyroiditis?
destructive attack of the thyroid by T cells; most common cause of hypothyroidism
What is abacavir?
a nucleoside reverse transcriptase inhibitor used to treat HIV/AIDS
What happens to cause a positive Mantoux skin test?
PPD is presented on MHCII by dendritic cells- Th1 memory cells activated- produce IFNgamma- attract macs- inflammation occurs
Hyperacute rejections are common in _____.
xenografts
What is Sjogren Syndrome?
autoimmune rxn to exocrine glands, esp tears and saliva
