CD164 identifies CD4+ T cells highly expressing genes associated with malignancy in Sezary syndrome: the Sezary signature genes, FCRL3, Tox, and miR-214

Sezary syndrome (SS), a leukemic variant of cutaneous T-cell lymphoma (CTCL), is associated with a significantly shorter life expectancy compared to skin-restricted mycosis fungoides. Early diagnosis of SS is, therefore, key to achieving enhanced therapeutic responses. However, the lack of a biomarker(s) highly specific for malignant CD4(+) T cells in SS patients has been a serious obstacle in making an early diagnosis. We recently demonstrated the high expression of CD164 on CD4(+) T cells from Sezary syndrome patients with a wide range of circulating tumor burdens. To further characterize CD164 as a potential biomarker for malignant CD4(+) T cells, CD164(+) and CD164(-)CD4(+) T cells isolated from patients with high-circulating tumor burden, B2 stage, and medium/low tumor burden, B1-B0 stage, were assessed for the expression of genes reported to differentiate SS from normal controls, and associated with malignancy and poor prognosis. The expression of Sezary signature genes: T plastin, GATA-3, along with FCRL3, Tox, and miR-214, was significantly higher, whereas STAT-4 was lower, in CD164(+) compared with CD164(-)CD4(+) T cells. While Tox was highly expressed in both B2 and B1-B0 patients, the expression of Sezary signature genes, FCRL3, and miR-214 was associated predominantly with advanced B2 disease. High expression of CD164 mRNA and protein was also detected in skin from CTCL patients. CD164 was co-expressed with KIR3DL2 on circulating CD4(+) T cells from high tumor burden SS patients, further providing strong support for CD164 as a disease relevant surface biomarker.