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Sezary Syndrome (SS) is an aggressive form of cutaneous T-cell lymphoma with invasion of leukemic cells in both the peripheral blood and skin. We utilized oligonucleotide microarray to interrogate the expression of 22,215 known genes using the Affymetrix Human Genome U133A Array. We used RNA of sorted CD4 T-lymphocytes from peripheral blood lymphocytes of healthy individuals either in the resting phase (T-CD4R) or activated (T-CD4A) with a bacterial superantigen (toxic shock syndrome-toxic-1). We compared these RNAs to sorted and clonal RNA samples derived from SS patients (T-CD4S) (> 95% were tumor cells as assed by staining with Vbeta monoclonal antybody). Genes that were significantly differentially expressed between the three groups were identified by using dChip software. We found a total of 447 genes that showed a greater than twofold change between T-CD4S and T-CD4R. Among these genes, 64 genes were down-regulated and 373 were up-regulated. Similarly, 257 genes showed a greater than twofold change in expression, with down-regulation of 57genes and up-regulation of 200 genes in T-CD4S vs. T-CD4Rcells + T-CD4A. In order to find most predictive genes that distinguish each of three groups we used Prediction analysis for microarrays (PAM) . By using this supervised analysis method we found 51 genes which are the best predictors among T-CD4S, T-CD4A and T-CD4R. Functional studies on several of these gene will be presented. Furthermore to investigate genetic aberrations in CTCL we started a genome-wide study on SS patients; using a high-throughput technique, represented by single nucleotide polymorphism (SNP) array, we allelotyped tumour and autologous normal samples for over 10,000 SNPs in an initial set of 5 patients. Our preliminary results show that: (I) LOH (Loss Of Heterozygosity) involve mainly chromosomes 9, 10 and 17, which is in a good agreement with literature data obtained with more traditional molecular and cytogenetic techniques, and (II) the measurement of DNA copy number changes show a good correlation with CGH (Comparative Genomic Hybridization) data available for a subset of the analyzed patients.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]