Class I HLA antigen deficiency and familial bronchiectasis: Clinical and laboratory study and review of the literature

Our team has managed two children derived from a consanguineous union, both suffering from pansinusitis with nasal polyposis, chronic otorrhoea and diffuse bronchiectasis. These two children presented a class I HLA deficiency (bare lymphocyte syndrome [BLS] type I) and a functional deficit of their NK cells. In the light of the most recent data concerning antigen presentation by class I molecules and the resulting cellular interactions, we describe the genetic basis for this syndrome in our two patients. Both children had an autosomal recessive mutation of the TAP:! gene coding for the peptide carrier protein. As a result of this mutation, the peptides likely to be presented by class I HLA molecules were not transported out of the cytosol, the cellular compartment in which they are generated, towards the lumen of the endoplasmic reticulum, the compartment where they associate with newly synthesized class I HLA molecules. This results in defective assembly and instability of class I HLA molecules. Comparative analysis of the rare cases of BLS published to date allows a brief description of the symptoms and comparison of the currently available laboratory data. The frequency of this syndrome could possibly be underestimated. We believe that the expression of class I HLA molecules expression should be studied in all patients with unexplained bronchiectasis or sino-bronchial syndrome, regardless of their age.