Flashcards in Immune deficiencies Deck (18):
2 T cell deficiencies, and their consequences
Bare Lymphocyte Syndrome,
More viral and fungal infections, and early malignancies.
B cell deficiencies (4)
Common variable immune deficiency,
Selective IgA deficiency,
More bacterial infections, and some toxins.
Phagocyte deficiencies (4)
Leukocyte adhesion defiency,
Chronic granulomatous disease,
More bacterial and fungal infections, more abscesses.
Bare Lymphocyte Syndrome
No HLA in thymus, so T cells. (Type 1 lacks MHC I, so no CD8, and 2, II (CD4).)
Type 2 more common.
B cell class switch needs CD4, so less IgA and IgG.
Associated with Primary Sclerosing Cholangitis.
Unwell by 3 months old.
Cardiac abnormality (tetralogy),
Cleft palate/lip and low set ears,
Hypocalcaemia / hypoparathyroidism.
22q11.2 deletion (75% sporadic).
3rd and 4th pharyngeal pouches don't develop.
Tx: thymus transplant.
X-linked Tyrosine kinase defect.
No mature B cells, so no Abs.
Symptoms after 3-6 months old.
Common Variable Immune Deficiency
Low IgG, IgA and IgE.
Many genetic causes, including MHC III deficiency.
Failure to thrive, recurrent infections, autoimmune and granuomatous disaeases.
Selective IgA Deficiency
Affects 1 in 600 Cauasians, 70% asymptomatic.
Recurrent gastro and respiratory infections.
Xq26 (boys). Defect in CD40, CD40L, CD154 or AICDA.
Baby boys with recurrent bacerial infections (Pneumocytis carinii) and FTT.
T cells can't communicate with B cells, so no class switching, so IgM only.
Less lymphoid tissue: no germinal centre development.
Risk of autoimmunity and malignancy.
Tx for B cell deficiencies
Vaccines in IgA def only.
Severe Combined Immune Deficiency
Lymphoid precursor problem:
- X-linked: IL2-Receptor mutn;
- Adenosine deaminse deficiency;
- Adenylate kinase 2 malfunction: Reticular dysgenesis.
Recurrent infections (bubble babies), FTT, persistent diarrhoea, early death.
T cells low, B cells low or normal, Abs low.
Severe congenital neutropaenia.
Autosomal recessive, HAX-1.
Dx: Chronically low neut, arrested neut precursor maturation in BM.
Tx: G-CSF, Abx, ?BMT.
Leukocyte Adhesion Deficiency
No Leukocyte adhesion markers.
- LAD 1: deficiency of beta 2 integrin subunit (CD18);
- LAD 2: much rarer. severe growth restriction, mental retardation.
Life threatening neonatal bacterial infections.
High neutrophil count. Delayed umbilical cord separation.
Chronic Granumlomatous Disease
Usually X-linked, many mutns.
Failure of oxidative killing:
- negative Nitro-Blue Tetrazolium as no H2O2 (stays yellow);
- dihydrorhodamine (DHR) not oxidised to rhodamine.
Pneumonia, abscesses, suppurative arthritis.
Can resist catalase -ve bacteria.
Tx: trimethorpim, itraconazole, interferon, ?SCT.
Every 3 weeks, a few days of neutropaenia.
Most severe form of SCID (adenylate kinase 2).
Missing all blood cells but RBCs.
Fatal v early unless BMT.
Low platelets, so brusing and bloody diarrhoea.
Low IgM, so recurrent infections.