Differential expression of cell surface antigens on subsets of CD4+ and CD8+ T cells.

Background: The assessment of relative antigen density on Tcell subsets is a feature of antigen expression that is infrequently characterized. Defining phenotypic differences is a first step in understanding associated differences in function. Additionally, a better understanding of T cell heterogenity may aid in clinical diagnoses. Materials/Methods: to further elucidate phenotypic differences of Tcell subsets, and begin to determine what information relative antigen density contributes to immunology, we analyzed normal human peripheral blood. T cells for a variety of immunophenotypic (CD2, CD3, CD4, CD5, CD7, CD8, CD45RA, CD45RO, TCRalphabeta) and light scatter characteristics using 6 color flow cytometry. T cell leukemia specimens were also analyzed. Results: Our data show that statistically significant immunophenotypic differences exist between susets of human CD4 and CD8 Tcells. Normal Tcells express different levels of relative antigen density for some antigens compared to malignant T cells. Conclusions: Significant differences are seen in relative antigen density for several cell surface markers between CD4+ and CD8+ Tcells. Nether donor source nor flow cytometric calibration account for these differences. The data are applied to specimens from patients with T-lineage acute lymphoblastic leukemia to show how antigen density can be used clinically in aiding to diagnose disease. The data presented here can be use to further invetigate these cell populations for functional differences.