Skewed expression of activation, differentiation and homing-related antigens in circulating cells from patients with cutaneous T cell lymphoma associated with CD7(-) helper lymphocytes expansion

Mycosis fungoides and Sezary syndrome represent the most frequent forms of cutaneous T cell lymphoma. Both are characterized by skin infiltrating and/ or circulating malignant cells displaying a CD4(+)CD7(-) phenotype in the m ajority of cases, Because an expansion of CD4(+) CD7(-) cells may also be f ound in inflammatory dermatoses or in the aging process, we evaluated, by f low cytometry, the relationship between CD7 expression and the distribution of differentiation/activation or homing antigens on peripheral blood lymph ocytes from 36 cutaneous T cell lymphoma patients and from healthy donors. CD4(+) CD7(-) cells were increased in all patients with cutaneous T cell ly mphoma. As a consequence, the CD7(+/-) ratio was reduced in stage I-II myco sis fungoides (3.96 vs 6.55 in healthy donors), and inverted in stage III-I V MF and Sezary syndrome (0.28 and 0.12 respectively), In the late stage of disease, the CD7+/- inverted ratio was strictly related to the expression of CD15s, CD60, and CD45R0, and the lack of expression of CD26 and CD49d, I nterestingly, in leukemic patients, this phenotype was also associated with peculiar morphologic (large size) or phenotypical (CD3(dim) expression) ch aracteristics. Furthermore, a progressive reduction of circulating CD8(+) c ells was also seen throughout all stages of disease, The presence of these populations in cutaneous T cell lymphoma at late phases of disease and Seza ry syndrome suggests that all of these molecules may play an important part in the activation pathway and skin homing of circulating T cells in lympho proliferative disorders. Therefore, this may constitute a distinctive featu re in cutaneous T cell lymphoma patients with more aggressive characteristi cs.