immunology Flashcards
How is SCID diagnosed
On NBS, SCID is diagnosed using TREC (Tcell receptor excision circles), a byproduct of T cells. SCID pts have low TREC. X-linked is most common.
What is Bruton’s agammaglobulinemia?
Aka X-linked agammaglobulinemia. Deficiency in B-cell maturation, so there is absence of plasma cells. The defective gene is bruton’s tyrosine kinase. Illness tends to occur once maternal Ab wear off around 4-6m. Tx w/ IVIG. Frequent infections with encapsulated bacteria (strep, staph, haemophilus)
Wiskott Aldrich Syndrome
X linked, WASP gene. Recurrent bacterial infections, ezcema, thrombocytopenia with bleeding, and IgM deficiency.
What is Leiner disease?
Rare deficiency of complement components, most commonly C5. Assc with subherroic dermatitis, intractable diarrhea, recurrent bacterial (gram -) infections. Tx: FFP infusions.
What is SCID?
Lack T cell, maybe B cell (but definitely less effective without T cells) and NK cells. Marked with lymphopenia. They present with diarrhea, repeated infections and FTT.
What is CGD and how is it diagnosed?
CGD is a deficiency in macrophage ability to kill intracellular bacteria. It is due to deficiency in NADPH oxidase, unable to produce respiratory oxidative burst. Usually doesn’t present until >3m. Susceptible to catalase producing bacteria (Staph, Serratia, Nocardia, Aspergillus) Diagnosed with nitroblue tetrazolium dye test - the leukocytes are unable to reduce the dye to deep blue color, will remain yellow. OR diagnose with dihydrohodamine assay looking at peroxide generation in phagocytes. Patients die in 3-4th decade.
What is Kostmann syndrome?
Severe congenital neutropenia (ANC <200 at birth) causing arrest of neutrophil maturation. Can present with life threatening bacterial infections. Tx: GCSF and BMT
how does toxoplasmosis present in mom?
most are asymptomatic. 15% will have flu like symptoms and lymphadenopathy.
For the fetus - severity is worse if infection is earlier in pregnancy but rate of transmission is higher if infection is late in pregnancy
What are the differences between two complement pathways?
Classic: ab meets ag —> immune complex. C1, 4, 2, 3
Alternative: can be Ab independent
The two meet at c3
What is the most complement deficiency?
What is c1-4 assc with?
What is c5-9 assc with?
Mc: c2
C1-4: increased risk of bacterial infections
C5-9: increased risk of neisseria
How is neutrophil response different in neonates?
Poor adherence to endothelium, poor chemotaxis response
Similar phagocytosis and degranulation
What is the natural course of B cell production?
Start in liver at 7 weeks, move to bone marrow by 30 weeks
At term, same proportion but higher absolute number than adults
Peaks at 4 m
when does the baby start making IgA? IgM?
fetus will start making IgM (75% adult levels by 1y)
IgA starts after birth (20% adult levels by 1y)
in pregnancy the T cell response switches from what to what? Does Treg go up or down?
TH1 to TH2 (Ab mediated) enhanced Treg (to inhibit immune system)
what are the three kinds of B cells?
innate response against thymus-independent Ag, low affinity Ab w/ broad specificity
Marginal zone: in spleen
B1: in peritoneal and pleural cavities
adaptive response against thymus-dependent Ag, high affinity Ab w/ high specificty
B2: follicular b cells
