Sunday, 31 October 2010

MRCP revision battle 38.3: T cell disorders

T cells are lymphocytes involved in cell-mediated immunity.  T cells mature in the thymus.

T cell disorders result in increased susceptibility to virus', mycobacteria and fungi.

Examples of T cell disorders include:

1. DiGeorge
  • defect in development of thymus and 3rd/4th branchial arches
  • mnemonic CATCH-22:
    • cardiac abnormalities (tetralogy of fallot)
    • abnormal faies
    • thymic aplasmia --> lack of T cells
    • cleft palate
    • hypocalcaemia (due to absent parathyroids)
    • 22 - recessive inheritance on chromosome 22

2. Nezelof syndrome
  • absent thymus
  • often some B cell involvement

3. Purine nucleoside phosphorylase deficiency
  • prevents development of T cells

Onto the final battle of this dull triad - combined B and T cell disorders