Aberrant expression of T-plastin in Sezary cells.

Mycosis fungoides (MF) and its leukemic variant, Sezary syndrome (SS), are the most common cutaneous T-cell lymphomas, with a combined incidence of 0.36 of 100,000 person-years. Although thought to be closely related to mature T-helper cells, the true nature of the cancer cells in MF/SS is unknown. In addition, there is no known specific marker for MF/SS cancer cells, which can result in difficulties in the diagnosis and treatment. To identify MF/SS-specific markers, Sezary cancer cells were analyzed with a global genomic screening tool, the modified representational difference analysis. It was discovered that unlike T-helper cells from healthy individuals or patients with nonmalignant dermatoses, Sezary cells from most patients with Sezary syndrome aberrantly expressed T-plastin mRNA and protein. This is the first time T-plastin protein, a cytoplasmic protein regulating actin assembly and cellular motility, has been detected in the hematopoietic cells. Therefore, T-plastin has the potential to be a Sezary cell-specific marker valuable for diagnostic and treatment of Sezary syndrome.