Multicolor Cytoenzymatic Evaluation of Dipeptidyl Peptidase IV (CD26) Function in Normal and Neoplastic Human T-Lymphocyte Populations
| Autor: | Mark Shenkin, Natalia Zacharievich, Phillip Ruiz |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Microbiology (medical)
Dipeptidyl Peptidase 4 Clinical Biochemistry Immunology Thymus Gland Peripheral blood mononuclear cell Article CD19 Dipeptidyl peptidase Substrate Specificity Immune system T-Lymphocyte Subsets Tumor Cells Cultured Humans Immunology and Allergy Cells Cultured Fluorescent Dyes biology Rhodamines Dipeptides T lymphocyte Flow Cytometry Molecular biology Leukemia Lymphoid Thymocyte biology.protein Antibody CD8 |
| Zdroj: | Clinical Diagnostic Laboratory Immunology. 5:362-368 |
| ISSN: | 1098-6588 1071-412X |
| DOI: | 10.1128/cdli.5.3.362-368.1998 |
| Popis: | Dipeptidyl peptidase IV (DPP IV), also identified as the glycoprotein CD26, is a transmembrane 110- to 120-kDa serine aminopeptidase involved in immune responses by influencing T-cell costimulation and by cleaving cytokines. Additionally, CD26 is a nonintegrin receptor that contains a binding site for extracellular matrix and other molecules. In order to further define the expression and functional activity of this membrane exopeptidase in human T cells, we developed a nondisruptive, four-color cytofluorogenic assay that utilizes three separate antibodies to cell-surface molecules (e.g., CD4/CD8/CD26 and CD19/CD56/CD26) along with a rhodamine 110-conjugated dipeptide substrate that allows the measurement of DPP IV activity in phenotypically defined cells. We found normal human thymi to have notable differences in time-dependent DPP IV activity among the thymocyte subsets defined by their CD4/CD8 phenotype, with CD4 − /CD8 − thymocytes containing less DPP IV activity than cells expressing CD4 and/or CD8 (i.e., maturing). CD26 positivity was moderately intense in thymocytes and tended to identify cells with higher DPP IV activity. The four-color technique was also used to examine mature peripheral blood lymphocytes, along with an assortment of leukemias and transformed T-cell lines. These experiments revealed that while DPP IV was consistently evident in normal T cells, neoplastic T cells could vary in their expression patterns. Furthermore, the presence (or intensity) of surface CD26 in some abnormal T cells and certain normal peripheral blood mononuclear cells was separable from the level of DPP IV measured intracellularly. Our results established that multicolor cytofluorographic analysis can be a practical means to measure DPP IV activity in various human cell populations. Furthermore, we found that DPP IV activity could vary in T cells according to their differentiation status and that under certain circumstances surface CD26 expression can be disassociated from the level of measured enzyme (i.e., DPP IV) activity. |
| Databáze: | OpenAIRE |
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