Aberrant expression of chemokine receptors in lymphoma cells through flow cytometry-based segregation in patients with mycosis fungoides

Phenotypic abnormalities such as loss of CD7 and CD26 and decreased expression of CD2, CD3, CD4, and CD5 are often observed in lymphoma cells in patients with mycosis fungoides (MF) and Sézary syndrome (SS). These findings help diagnosis and prognosis of MF/SS. Here we examined the expression of chemokine receptors in a distinct T cell subpopulation in peripheral blood from a patient with MF through flow cytometry-based segregation. Peripheral blood mononuclear cells were obtained from a patient with erythrodermic MF, and cell surface markers were studied by flow cytometry. We sorted the cells and investigated their morphology, clonality of T-cell receptor rearrangement, and expression of chemokine receptors. CD3+/CD4+ T cells from the patient's peripheral blood were separated into two subpopulations; one exhibiting slightly decreased level of CD4 (CD4dim), the other with obviously lower level of CD4 (CD4dull) than those in healthy controls. Both CD4dim and CD4dull subpopulations included large lymphocytes with cleaved nuclei, and demonstrated a clonal T-cell receptor rearrangement by PCR. CD26- cells were observed around 70% in the both two subpopulations; however, CD7− cells were 82.5% and 3.7% in CD4dull and CD4dim subpopulations, respectively. Real-time PCR analysis revealed that CD4dull subpopulation demonstrated increased levels of CCR4, CCR7 and CXCR4 by three fold compared with those in CD4dim subpopulation or healthy controls. As reported, malignant nature of lymphoma cells might be associated with aberrant surface phenotype, by which we could distinguish them from normal to less malignant CD4+ T cells. In addition, they preferentially exhibited chemokine receptors CCR4, CCR7 and CXCR4, which might underlie skin infiltration and could be therapeutic targets.