CD4 and lysosomal storage disease: We demonstrated here that typical SAI was associated with increased CTLA-4 expression on CD4+ lymphocytes, and a marked correlation was found between CTLA-4 expression and a marker of mTOR pathway mediated autophagic–lysosomal disorder, LC3II; the accumulation of LC3II could be attributable to increased autophagosome formation or decreased lysosomal fusion and degradation.