Absence of CD26 expression is a useful marker for diagnosis of T-cell lymphoma in peripheral blood.
We report flow cytometric characterization of surface CD26 expression in 271 peripheral blood samples from 154 patients evaluated for the presence of a T-cell lymphoproliferative disorder, primarily mycosis fungoides/Sézary syndrome (MF/SS). The presence of morphologically identifiable tumor cells on peripheral blood smears was the criterion for lymphomatous involvement. In 66 of 69 samples from 28 patients, we identified an abnormal CD26-/dim T-cell population that was distinct from the variable CD26 expression seen in normal peripheral blood T cells. This population was CD26- in 23 patients and weakly CD26+ in 5 patients. CD7 was more variably expressed in MF/SS tumor cells, allowing recognition of a distinct, quantifiable abnormal T-cell population in only 34 of 69 involved samples. An increased CD4/CD8 ratio and lower surface expression of CD4 in tumor cells also helped separate the CD26-/dim atypical population for quantification. In 35 blood samples from other types of T-cell tumors, tumor cells in 10 of 11 morphologically involved cases showed absent/dim CD26. Although capable of detecting abnormalities in most cases of MF/SS, CD7 expression does not provide as clear a separation of the neoplastic population and can be replaced by CD26 staining in routine peripheral blood flow cytometric screening of MF/SS patients.
Jones
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D
Division of Pathology and Laboratory Medicine, University of Texas-M.D. Anderson Cancer Center, Houston, USA.
Dang
N H
NH
Duvic
M
M
Washington
L T
LT
Huh
Y O
YO
D019011:Antigens, CD7 / Q000097:blood; D000945:Antigens, Differentiation, T-Lymphocyte / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D018819:Dipeptidyl Peptidase 4 / Q000097:blood*; D005434:Flow Cytometry; D006801:Humans; D016399:Lymphoma, T-Cell / Q000097:blood / Q000175:diagnosis; D008232:Lymphoproliferative Disorders / Q000097:blood; D009182:Mycosis Fungoides / Q000097:blood / Q000175:diagnosis*; D012751:Sezary Syndrome / Q000097:blood / Q000175:diagnosis*; D016176:T-Lymphocyte Subsets / Q000145:classification
D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte; D014408:Biomarkers, Tumor; D018819:Dipeptidyl Peptidase 4