Mucopolysaccharidoses: ultrastructure of leukocyte inclusions.

Ultrastructural study of leukocytes from 7 patients with mucopolysaccharidosis (MPS) I, II, or III demonstrated a variety of membrane-bound inclusions in 34 to 68% of lymphocytes and larger mononuclear cells. The most common inclusions were membrane-bound vacuoles containing faintly osmiophilic material, but a variety of clear vacuoles, dense granular inclusions and myelin figures were also seen. Fingerprint profiles were present in small percentages in MPS II and III, indicating that they are not as specific as previously considered. Granulocytes, lymphocytes, and larger mononuclear cells from a patient with MPS VII showed many small and large membrane-bound vacuolated inclusions, some of which contained large dense granules. The presence of alterations in a readily accessible tissue such as blood indicates that ultrastructural study of leukocytes may be a useful adjunct in guiding further biochemical studies in MPS, especially in early or obscure cases.