Morphology of leukocytes from cats affected with alpha-mannosidosis and mucopolysaccharidosis VI (MPS VI).

The morphology and ultrastructure of circulating white blood cells from six Persian and from five Russian Blue/Siamese cats deficient in lysosomal activity of alpha-mannosidase and arylsulfatase B, respectively, were studied and compared to cells from corresponding normal and carrier cats. In cats with mannosidosis, light microscopic examination revealed vacuoles in lymphocytes and monocytes, whereas electron microscopic studies demonstrated additional vacuoles in neutrophils, eosinophils, and basophils. In cats with mucopolysaccharidosis VI (MPS VI), vacuoles containing metachromatic granules were observed in lymphocytes, neutrophils, eosinophils, and monocytes. Ultrastructural studies of these cells identified the accumulation of fibrillar material, which often was associated with lamellated membrane structures.