Identification of HNP3 as a tumour marker in CD4+ and CD4- lymphocytes of patients with cutaneous T-cell lymphoma.

Cutaneous T-cell lymphomas (CTCL) are characterized by malignant proliferation of skin homing T-cells. Although prognosis is generally good, reliable markers are needed to identify patients at risk for a more aggressive course. ProteinChip (SELDI) technology was used as a tool for the discovery of protein patterns in lymphocytes from patients with CTCL (n=25) and unaffected controls (n=25). Lymphocytes were separated in CD4+ and CD4- fractions by magnetic cell sorting (MACS). Each whole protein extract was analysed by ProteinChip technology. The resulting protein profiles were submitted for bioinformatic analysis including a clustering algorithm, a rule extraction, a rating and a rule-base construction step. For the generated combined rule base for the CD4- cell fraction, both the sensitivity and specificity for the prediction of CTCL reached 96%, while for the CD4+ fraction they were 92% and 84%, respectively, for sensitivity and specificity. The most significant peak at 3489Da could be identified as HNP3, an alpha-defensin, by immunocapturing. These results open up both the possibility for the use of this protein signature, especially HNP3, to more effectively monitor and screen CTCL, and the avenue to identify the other relevant peaks for a better understanding of the development of this tumour.