The Sézary syndrome cell: surface ultrastructural characteristics.

Peripheral blood mononuclear cells from a patient with Sézary syndrome which lacked E-rosette-forming ability and surface immunoglobulins, and which displayed a markedly depressed response to a variety of mitogens, were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) on 3 occasions. The first peripheral blood sample (smooth) differed significantly from two later samples (moderate numbers of microvilli) when surface characteristics were examined by SEM; these differences were confirmed by TEM. The Sézary syndrome cells in this patient may be related to a T lymphocyte which has lost certain surface markers and mitogen response characteristics through a process of de-differentiation.