Variable CD7 Expression on T Cells in the Leukemic Phase of Cutaneous T Cell Lymphoma (Sézary Syndrome)

Abstract

CD7, a molecule normally expressed on 90% of normal CD4+ T cells, is often deficient on the malignant T cells of cutaneous T cell lymphoma. To investigate the clinical and biologic implications of CD7 expression, blood lymphocytes from 42 patients with the leukemic phase of cutaneous T cell lymphoma (CD4/CD8 ratio of 10 or more with evidence of a T cell clone in the blood) were analyzed for level of expression of CD7 by flow cytometry. CD7 expression by cells did not clearly segregate into two distinct subgroups that are either CD7 positive or CD7 negative as generally thought; however, nine of 17 patients with a predominantly CD4+CD7+ tumor population on early studies became CD4+CD7- over time whereas the converse situation was not observed. In addition, of three patients with evidence of large tumor cells in the blood coexisting with smaller cells, discordant CD7 expression was observed in one instance. In lymph node specimens, the percentage of cells expressing CD7 and other T cell markers did not correlate with histologic evidence of involvement. CD7 expression on blood lymphocytes also did not correlate with patients' survival nor to serum IgE levels or blood eosinophil counts, a finding suggesting that this marker does not identify functional cell subsets that produce serum interleukin-4 or -5, respectively. We speculate that the level of CD7 expression on malignant T cells may be the effect of sustained antigen stimulation in vivo analogous to what has been proposed to occur with normal T cells during aging.

B7-H1 (PD-L1, CD274) suppresses host immunity in T-cell lymphoproliferative disorders

“…In cases where TCR V␤ usage was unknown, malignant T cells were identified as CD4 ϩ CD7 Ϫ cells, as these cells may lose the expression of T-cell markers, including CD7. 15 The aberrant loss of CD7 expression was confirmed at the time of diagnosis for all patients whose specimens were used in the current study. Frozen plasma samples were obtained from the Lymphoma SPORE Biospecimens Core Facility.…”

Expression of T-plastin, FoxP3 and other tumor-associated markers by leukemic T-cells of cutaneous T-cell lymphoma

“…On a smaller subset of patients, positive, but not statistically significant, correlations were also observed between T-plastin transcript levels and absolute counts of CD4 + CD26-cells (n = 21, ρ = + 0.286, p = 0.205), and Vβ + cells (n = 12, ρ = + 0.315, p = 0.306). The lack of correlation with CD4 + CD7-cells (n = 21, ρ = + 0.096, p = 0.674) reflects the fact that CD7 is variably expressed by neoplastic T-cells [43].…”

Flow cytometric immunophenotyping for hematologic neoplasms

“…However, CD7 Ϫ neoplastic cells must be distinguished from the small population of normal CD7 Ϫ T cells that are well recognized in the skin and blood and may expand in benign dermatoses and other reactive conditions. 72,73 In addition, it is important to recognize normal subsets of T cells, including T-cell receptor (TCR)-␥/␦ ϩ cells, that may lack staining for CD5, CD4 and CD8, and normal NK cells usually lack staining for CD5 and demonstrate variable lack of staining for CD8. 67 More frequently, rather than complete lack of staining, T and NK neoplasms demonstrate more subtle altered intensity of staining for antigens.…”