Utility of CD26 in flow cytometric immunophenotyping of T-cell lymphomas in tissue and body fluid specimens.
BACKGROUND
CD26 is expressed by most CD4+ T cells in normal peripheral blood specimens. Neoplastic T cells are frequently CD26- in mycosis fungoides/Sezary syndrome involving the peripheral blood. However, CD26 expression by reactive and neoplastic T cells in solid tissues and body fluids has not been fully characterized by flow cytometry (FC).


METHODS
Solid tissue and body fluid specimens were assayed for CD26 expression using four-color FC immunophenotyping, by qualitative assessment of population clusters, and by quantitation with comparison with isotype controls. Benign T cells were studied in reactive tissues and in the background of other malignancies.


RESULTS
Many T-cell lymphomas were dim or negative for CD26, whereas a few were brightly positive. In the majority of T-cell lymphomas, CD26 expression could potentially help identify aberrant population clusters. T cells in reactive tissue specimens and tumor-infiltrating T cells were commonly dim to negative for CD26.


CONCLUSIONS
Both T-cell lymphomas and reactive T cells in tissue and body fluid specimens often show low levels of CD26 expression. Therefore, quantitative methods may not reliably distinguish benign from neoplastic T cells in these specimens. However, CD26, in combination with other T-cell markers, can be helpful for identifying aberrant population clusters in T-cell lymphomas.
Pierson
Diane M
DM
Department of Hematopathology, U.T. M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Jones
Dan
D
Muzzafar
Tariq
T
Kersh
Marian J
MJ
Challagundla
Pramoda
P
Medeiros
L Jeffrey
LJ
Jorgensen
Jeffrey L
JL
D001826:Body Fluids / Q000276:immunology*; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping; D016399:Lymphoma, T-Cell / Q000276:immunology / Q000473:pathology; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D014018:Tissue Distribution
D018819:Dipeptidyl Peptidase 4