Indications of the Thymus-Derived Nature of the Proliferating Cells in Six Patients with Sézary's Syndrome

The Sézary syndrome consists of erythroderma, lymphadenopathy and abnormal mononuclear leukocytes. In four of six patients with this syndrome, the abnormal cells were smaller than the classic large Sézary cell. The membrane properties of circulating abnormal cells, studied by conventional stains, electron microscopy, cytogenetic analysis, immunofluorescence, and rosette formation, manifested similar ultrastructural and chromosomal characteristics whether the cells were large or small. The abnormal cells were devoid of membrane-bound immunoglobulin detectable by immunofluorescence, did not bind aggregated human IgG, were able to form spontaneous rosettes with sheep erythrocytes and, in the three patients studied, were killed by a specific rabbit antihuman T-cell antiserum. These findings indicate that these cells are related to thymus-derived lymphocytes. (N Engl J Med 289:341–344, 1973)