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CD3 bright lymphocyte population reveal γδ T cells
Author(s) -
Lambert Claude,
Genin Christian
Publication year - 2004
Publication title -
cytometry part b: clinical cytometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 61
eISSN - 1552-4957
pISSN - 1552-4949
DOI - 10.1002/cyto.b.20005
Subject(s) - cd3 , cd8 , microbiology and biotechnology , population , t lymphocyte , t cell , cytotoxic t cell , biology , monoclonal antibody , immunology , lymphocyte , t cell receptor , antibody , chemistry , antigen , medicine , immune system , biochemistry , in vitro , environmental health
Background In routine CD3/CD4/CD8 T‐cell analysis, a CD3 bright population of lymphocytes is frequently observed. The aim of the present study was to identify the immunological significance of such CD3 bright lymphocytes. Methods We analyzed samples from 31 healthy adult volunteers, 78 human immunodeficiency virus (HIV)‐positive, and 78 renal transplanted patients. Results A clearly distinct CD3 bright (frequently CD4 − /CD8 − ) T‐cell fraction was observed in 84% of donors and was directly correlated with the fraction of γδ T cells ( r 2 = 0.64). CD3 overexpression on γδ T cells was confirmed by a combination of monoclonal antibody staining (CD3‐ECD, γδTCR‐FITC, and αβTCR‐PE‐Cy5) or immunomagnetic purification of γδ T cells (i.e., MdFI 20 vs 8.86). The γδ T cells expressed CD8 polypeptide chains (α and β) in all possible combinations. The largest proportion, surprisingly, were cells expressing CD8ββ homodimers (43.8 ± 16.5%). CD8αα homodimers were expressed on 14.2% (± 12.3) of total γδ T cells, whereas CD8αβ heterodimers were expressed on 12.2% (± 7.5). We also observed a bimodal distribution of the intensity of CD3 fluorescence of γδ T cells in immunocompromised patients with a threshold at 105 cell/μl. CD3 bright γδ T cells were more frequently observed in HIV patients (29%) compared with renal transplant patients (11%) and healthy donors (3%; χ 2 test: P = 0.0007). Conclusions The simple observation of a CD3 bright T‐cell subset on CD3/CD4/CD8 routine analysis suggests a high γδ T‐cell fraction and, in our opinion, should be followed by a complementary analysis to determine precisely the number of γδ T cells and to identify their CD8α/β phenotype. When CD3 bright T cells/μl were more than 40%, high γδ T cells were detected in more than 87% of cases, with a specificity of 76%. Occasionally, the CD3 bright subset appeared to be strongly homogeneous, suggesting an oligoclonal proliferation that could possibly reveal a chronic localized stimulation or an early lymphoproliferative disorder. Because the γδ T cells have interesting immunological peculiarities, the clinical significance of their quantitative abnormality should be clarified in diseases such as HIV, organ transplantation, autoimmunity and lymphoma. © 2004 Wiley‐Liss, Inc.