ABSTRACT
BACKGROUND: Total T lymphocytes can be measured by CD3-fluorescein isothiocyanate (FITC)/CD4-phycoerythrin (PE) and CD3-FITC/CD8-PE. The difference in the CD3 percentages between these two determinations was evaluated. And, we characterized the CD3(+)CD4(-)CD8(-) T lymphocytes subset using the monoclonal antibody that detects gamma delta T lymphocytes receptors. METHODS: The T lymphocyte subset assay was performed on 221 samples. A two-color direct immunofluorescence flow cytometric assay was done using a Simultest IMK-Lymphocyte kit (Bec-ton- Dickinson, San Jose, CA, USA). If the difference between the CD3 determinations were greater than 3%, the entire procedure was reviewed and the flow cytograms were reanalyzed. In 71 among 221 samples the proportion of gamma delta T lymphocytes was determined. RESULTS: The difference between the CD3-FITC/CD4-PE tube and CD3-FITC/CD8-PE tube was 3.0%, 3.6%, 3.0%, 3.4%, and 2.4% in normal subjects, patients with chronic liver disease, patients with cancer, patients with other diseases, and children, respectively. The between-tube differences for CD3 exceeding 3% were found in 69 samples (31.2%). The proportion of gamma delta T lymphocytes was 0.81%, 2.46%, 2.50%, and 0.85% in normal controls, patients with chronic liver disease, patients with cancer and patients with other diseases, respectively. No correlation between gamma delta T lymphocytes and CD3(+)CD4(-)CD8(-) T lymphocytes was observed. CONCLUSIONS: The reproducibility of the total T lymphocytes should be improved because of the between-tube difference exceeding 3% in about one third of the cases. Additionally, CD3(+)CD4(-)CD8(-) T lymphocytes were composed of heterogeneous subsets including gamma delta T lymphocytes and their proportion might be considered to be related to individual variation.