Phenotype of Benign T-Cells Benign T-cells are positive for T-cell markers (CD2, CD3, CD5, and CD7), CD4 or CD8, CD26, CD38, CD43, CD45, TCRαβ, and are negative for HLA-DR.

Blood and Bone Marrow In normal blood samples (Table 5.1), the percentage of T-cells ranges from 32% to 81% (average 48%) with an average CD4:CD8 ratio of 3.6:1 (range 08:1 to 9.3:1). T-large granular lymphocytes (T-LGL cells) expressing CD2, CD3, CD5, CD7, CD8, and CD57 comprise between 0.1% to 14% of blood elements (average ~5%). Natural killer (NK) cells which are positive for CD2, CD7, CD56, and oen CD16 and negative for surface CD3 and CD5 comprise between 0.2% to 10% (average 3%). Dual CD4/CD8+ T-cells in blood comprise 0.2% to 1% of total events. No signicant population of CD10+ T-cells can be identied in blood samples. In normal bone marrow (BM) T-cells show similar FC features, with the main dierence being smaller number of T-cells and lower CD4:CD8 ratio when compared to blood. Samples from patients recovering aer chemotherapy for B-cell lymphomas/ CLL or acute leukemia oen show reversed CD4:CD8 ratio and increased number of NK cells and/or T-LGL cells.