Gene expression profiling of peripheral T-cell lymphoma including gammadelta T-cell lymphoma.

The gene expression profile of peripheral gammadelta T-cell lymphoma (gammadeltaTCL) has not been investigated. Using oligonucleotide microarrays, we analyzed total RNA from 7 patients with gammadeltaTCL (4 hepatosplenic, 1 cutaneous, 1 intestinal, and 1 thyroidal) and 27 patients with alphabetaTCL (11 peripheral TCL-unspecified, 15 angioimmunoblastic TCL, and 1 hepatosplenic). Unsupervised microarray analyses classified all hepatosplenic gammadeltaTCLs into a single cluster, whereas other gammadeltaTCLs were scattered within the alphabetaTCL distribution. We identified a T-cell receptor signature gene set, which accurately classified gammadeltaTCL and alphabetaTCL. A classifier based on gene expression under supervised analysis correctly identified gammadeltaTCL. One case of hepatosplenic alphabetaTCL was placed in the gammadeltaTCL grouping. gammadeltaTCL signature genes included genes encoding killer cell immunoglobulin-like receptors and killer cell lectin-like receptors. Our results indicate that hepatosplenic gammadeltaTCL is a distinct form of peripheral TCL and suggest that nonhepatosplenic gammadeltaTCLs are heterogeneous in gene expression.