NATURAL KILLER CELL DEFICIENCY IN PATIENTS WITH MUCOPOLYSACCHARIDOSES

Abstract

Mucopolysaccharidoses (MPSs) are a group of inherited metabolic disorders characterized by the deficient activity of catabolic enzymes in the lysosomes and its consequent abnormal accumulation of deposits of glycosaminoglycans. The lysosomal dysfuction caused by this irregular storage is responsible for the clinical manifestations seen in MPS. Once the lysosome is also important for normal functioning of the immune system, playing a key role in the expression of cellular membrane receptors, the presentation of antigens, the secretion of cytokines and phagocytosis, we presume that these processes may be impaired in patients with MPS. The presence of recurrent respiratory infections in these individuals may be a clinical clue of the immune dysregulation in MPSs. Natural Killer (NK) cells play an important role in first-line, innate defense against viral infection and tumor transformation. Their activation is the net result of signals emanating of inhibitory and activating receptors, among which the NKG2D activating receptor plays a major role. We evaluated the innate immunity of 15 patients with MPSs types I, II, IV and VI and performed the immunophenotyping of NK cells and the NKG2D receptors expression by Flow Cytometry. All MPSs patients have NK cells deficiency and decreased NKG2D receptors expression on NK cells in 2 patients. We report here that MPSs patients have a deficiency of innate immunity with NK cells deficiency. To the best of our knowledge, these findings have not been previously described.