A 6-year-old boy presents with recurrent sinopulmonary infections and chronic ulcerating skin lesions caused by respiratory viruses over the past 2 years. Vital signs show HR 102/min, RR 24/min, temp 37.2°C, SpO2 92% on room air. Flow cytometry reveals CD8+ T cells 8% (normal 15-25%), CD4+ T cells 32% (normal), and normal immunoglobulin levels. Chest X-ray shows bronchial wall thickening without pneumonia. A defect in which of the following is most likely present?
- A)BTK required for B cell maturation
- B)CD40 ligand on activated helper T cells
- C)TAP transporter required for peptide loading onto MHC IGABARITO
- D)C5 through C9 complement proteins
- E)AIRE protein required for thymic negative selection
Explicação
MHC class I deficiency results from defective TAP mediated transport of endogenous peptides into the endoplasmic reticulum for loading onto MHC I. CD8 positive T cell maturation and antiviral cytotoxic responses are impaired, so patients have recurrent viral a... Ver explicação completa e trilha adaptativa →