Immunology Flashcards
Describe the 2 signal process of T-cell activation from an APC.
T-cell activation requires 2 signals between the T-cells and APC:
Signal 1: T-cell [TCR:peptide:MHC] APC – necessary but not sufficient
Signal 2: T-cell [CD28:B7] APC – activation of T-cell with IL-2 release and T-cell proliferation
What are CTLA-4 receptors?
CTLA-4 receptors are the doppelganger of CD28 in that they bind preferentially to B7 on APC cell and prevent the activation and proliferation of T-cells.
Normal function is to prevent autoimmunity.
Which interleukin is implicated in T-cell proliferation?
IL-2 is released upon activation of T-cell to promote T-cell proliferation
What is polyarteritis nodosa (PAN)? Which sex is it more likely to affect?
Medium vessel vasculitis that affects M > F.
Which organ systems are implicated in polyarteritis nodosa (PAN)? Which organ system that tends NOT to be implicated?
Systemic - fever, malaise, weight loss 80%
Neuropathy - mononeuritis multiplex, polyneuropathy 75%
Arthralgia/myalgia 60%
Skin - livedo reticularis, pupura, ulcers 50%
Renal disease 50%
GI - abdominal pain, rectal bleeding 40%
HTN - new onset 35%
Orchiditis - testicular pain 20%
Lungs tend NOT to be involved.
Which viral illness is polyarteritis nodosa (PAN) associated with?
Hep B
What are the investigations for polyarteritis nodosa (4)?
- Angiogram (mesenteric/renal) for vasculitis
- Hep B serology
- Complement C3/C4 - normal
- Biopsy affected tissue
True/False: complement C3/4 is elevated in polyarteritis nodosa (PAN).
False.
What is the treatment of polyarteritis nodosa (s)?
- Steroids
- Cytotoxics
- Treat Hep B is relevant.
What are 6 conditions are associated with pANCA (use mnemonic).
My Personal Computer Is Really Good! … So i Permanently ANCHORED it to my desk!
(MPCIRG = pANCA)
Microscopic polyangitis (MPA)
Polyarteritis nodosa (PAN)
Churg-Strauss (EGPA/Eosinophilic GPA)
IBD (esp. UC)
RPGN - Rapidly Progressive Glomerulonephritis (necrotising/cresentic GN)
Goodpasture’s Syndrome (anti-GBM)
What is the new name for Wegener’s Granulomatosis?
GPA (Granulomatosis with PolyAngiitis)
How is GPA (granulomatosis with polyangiitis) diagnosed (biochemistry/immunofluorescence/histopathology/urine)?
Biochem: c-ANCA, PR3
Immunofluorescence: Pauci-immune
Histopathology: necrotising medium vessels + granulomas
Urine: postive urinary sediment
Which organ systems are implicated in GPA (granulomatosis with polyangiitis)?
ELK:
ENT
Lung - PE (20x risk)
Kidney - haematuria/RPGN
What type of glomerular disease is GPA (granulomatosis with polyangiitis) associated with?
Rapidly-progressive GN (RPGN)
True/False: GPA (granulomatosis with polyangiitis) is more likely to relapse than Microscopic Polyangitis?
True.
What is the treatment of GPA (3)?
- Rituximab + prednisone (Rituximab as good as cytotoxic with less SEs)
- If RPGN then IVIG
- Maintenance = AZA or MTX (only if cytotoxics used)
- Relapse = cytotoxics then AZA afterwards
What is MPA (Microscopic Polyangiitis)?
Necrotising small vessel vasculitis
What Ab-staining occurs in MPA (Microscopic Polyangiitis)?
Easy MPA (word contains MPo + P-anca + Pauci-immune):
- MPO
- p-ANCA
- pauci-immune
How is MPA (Microscopic Polyangiitis) diagnosed (biochemistry/immunofluorescence/histopathology/urine)?
Biochemistry: p-ANCA / MPO
Immunofluorescence: pauci-immune, small % with anti-GBM (Goodpastures)
Histopathology: necrotising small vessels
Urine: positive urinary sediment
What are the points of differentiation between MPA and GPA (biochemistry/immunofluorescence/histopathology/urine)?
Biochem:
GPA = c-ANCA/PRS
MPA = p-ANCA/MPO
Histopathology:
Both are necrotising.
GPA = vasculitis of medium-sized vessels + granulomas
MPA = vasculitis of small-sized vessel with NO granulomas
Immunofluorescence and urine: Same - both pauci-immune and with positive urinary sediment.
Use:
- ‘WE CAn P-Pass this wRITten eXamination?’ (5)
- MPA (contains 3 things: MPO/p-ANCA/Pauci)
Which is more severely affected in MPA; kidneys or lungs?
MPA: Kidneys > Lungs
‘Malaysia Pacific Airlines flies to Kuala Lumpur’
Glomerulonephritis +/- RPGN»_space; alveolitis / haemoptysis
What is the treatment for MPA (3)?
- Rituximab + Prednisone
- Plasmaphoresis improved renal outcomes
- Maintenance: AZA / MTX (only if cytotoxic used).
What is another name for Churg-Strauss?
EGPA (eosinophilic granulomatosis with polyaniitis)
Which HLA is Churg-Strauss/EGPA associated with?
HLA-DRB4
What are the clinical features of Churg-Strauss/EGPA?
Mnemonic: ‘Strauss was an A-PLUS Nazi composer’
(Churg-Strauss is an Asthma ‘PLUS’ syndrome / Neuropathy)
Typically:
Asthma / Eosinophilic pneumonia ‘plus’ neuropathy (peripheral neuropathy, mononeuritis multiplex)
Other ‘plus’ syndromes:
Glomerulonephritis
Cardiac (myocarditis, coronary arteritis)
Dermatological (purpura)
How often is p-ANCA positive in Churg-Strauss/EGPA?
50% of EGPA is p-ANCA PA is 50% of EGPA letters…
What are the histopathological findings of Churg-Strauss/EGPA?
Granuloma + Eosinophils in small/medium vessels
What single agent is used in Churg-Strauss/EGPA?
Prednisone only.
Compare:
- GPA
- MPA
- EGPA
in terms of vessel size, histopath, biochem/immunofluorescence (if relevant)
- GPA
Medium vessels
Necrotising vessels + Granulomas
c-ANCA / PR3 / pauci-immune - MPA
Small vessels
Necrotising vessels only
p-ANCA / MPO / pauci-immune - EGPA
Small/Medium vessels
Granulomas + Eosinophils (extravascular)
p-ANCA (50%)
Patient with fever, haemoptysis and positive urinary sediment and p-ANCA positive.
What are the DDx?
How might the DDx be differentiated?
DDx for positive p-ANCA = MPA, PAN, Churg-Strauss, IBD, RPGN, Goodpastures.
‘My Personal Computer Is Really Good, so i Permanently ANCHORED it onto my desk’
NOT PAN - tends not to involve lungs.
NOT Churg-Strauss (EGPA) - no asthma/eosinophilia
NOT IBD/RPGN - not consistent with presentation
Therefore DDx: MPA vs. Goodpastures (Anti-GBM)
Need Biopsy:
Anti-GBM = Anti- GBM (obviously)
Necrotising pauci-immune small vessel = MPA
What might cryoglobulinaemia be associated with?
Which types?
Many things.
Type I = lymphoproliferative disorders
Type II = acute Hep C
Type III = autoimmune disorders (SLE/Sjogrens/PAN/RA)
Other: infections, renal transplants, idiopathic.
Which cells types are IL-7 receptors found in?
What is it’s normal function?
B-cells T-cells Lymphoid progenitor cells
Interaction with IL-7 permits development of maturation, proliferation and survival of B-cells and T-cells
Mutation of the IL7-R genes is associated with which 2 conditions?
- Multiple sclerosis
2. SCID (severe combined immune deficiency) state - no T-cells, normal B-cells and NK-cells
With SCID, what cell line is deficient and which are preserved?
No T-cells
Normal B-cells and NK-cells.
NB: SCID aka T-B+NK+SCID
Which cell from the innate immune system is important in the control of viral infections?
NK-cells
IL-5 is produced by which 2 cell types?
What is the function of IL-5 (2)?
Th-2 cells (helper T-cells) and mast cells
Functions:
- Stimulates B-cell growth and increases Ig production.
- Eosinophil activation
IL-3 is produced by which 2 cell types? What is the function of IL-3 (2)?
T-cells and basophils.
Functions:
- Differentiation of multipotent haematopoetic stems into myeloid progenitor cells or lymphoid progenitor cells (requires addition of IL-7)
- Stimulates the proliferation of myeloid lineage cells in conjunction with other chemokines: EPO, GM-CSF and IL-6.
What are the cytokines that encourage a Th1 vs. Th2 response (i.e. helper T-cells)?
What is the utility of a Th1 response vs. Th2 response?
Naive helper T-cells (CD4) attach to APC via MHC II.
Thn = naiive T-cells Th0 = undifferentiated Th cell
Th1 response:
Normal fn: intracellular microbes.
Abnormal fn: autoimmunity
Cytokines: IL-12/IFN-alpha > Thn or Th0 > Th1 > IFN-gamma/IL-2
NB: alpha then gamma (in order)
Th2 response:
Normal fn: humoral immunity
Abnormal fn: allergies
Cytokines: IL4 > Thn or Th0 > Th2 > IL-4/IL-5/IL-10/IL-13
NB: Th2 have no ‘2’ in any of the cytokines.
Which helper T-cell is implicated in autoimmune disease and intra cellular infections?
Th1
Which helper T-cell is implicated allergies and humoral immunity?
Th2
Which 4 cytokines are involved in Th1 response?
IL2, IL12, IFN-alpha, IFN-gamma
Which 4 cytokines are involved in Th2 response?
IL 4, 5, 10, 13