All of the following statements are true regarding ‘Bare lymphocyte syndrome’, except:-
Correct Answer: MHC overexpression
Description: BLS (Bare Lymphocyte Syndrome): Deficiencies in MHC class I or class II are called bare-lymphocyte syndrome, reflecting the absence of these proteins from cell surfaces. The impoant and ubiquitous role of MHC class I molecules is highlighted in patients with defective expression of all class I proteins. This rare immunodeficiency disorder can be caused by mutations in b2-microglobulin, a subunit of MHC class I proteins, or in the TAP proteins, which are vital to antigen presentation by MHC class I molecules. In early life, the TAP-deficient individual suffers frequent bacterial infections of the upper respiratory tract and in the second decade begins to experience chronic infection of the lungs. The most characteristic mark of the deficiency is the occurrence of necrotizing skin lesions on the extremities and the midface. These defects affecting MHC class I proteins result in impaired positive selection of CD8 T cells, depressed cell-mediated immunity, and heightened susceptibility to viral infection. Disorder Specific defect Impaired immune function Inheritance mode Bare-lymphocytesyndrome (BLS): MHCdeficiencies Class I: b2-Microglobulin, TAPpeptide transpoer, tapasin No/reduced MHC class I expression, reducing numberof CD8 T cells Autosomal Recessive (AR) Bare-lymphocytesyndrome (BLS): MHCdeficiencies Class II: Defect intranscription factorsactivating MHCII geneexpression No MHC class II molecules, reducing numbers of CD4T cells Autosomal Recessive (AR)
Category:
Pathology
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