Absolute numbers of circulating lymphocyte subpopulations in patients with indolent B-cell lymphomas and healthy donors. Whole blood samples were stained and analyzed by flow cytometry within 2 hours after phlebotomy. Horizontal bars, boxes, and whiskers represent median, 25%/75% quartiles, and range, respectively. (A) Bead-calibrated absolute cell numbers of CD4⁺, CD8⁺, and NK lymphocyte subsets. FL, n = 11; eMZL, n = 7; CLL, n = 9; MGUS, n = 6 patients. (B) Bead-calibrated absolute cell numbers of regulatory T cells. FL/eMZL, n = 13; CLL, n = 8; MGUS, n = 6 patients. (C) Retrospective analysis of data from the diagnostic immunophenotyping laboratory of the Freiburg Department of Hematology/Oncology. T-cell counts were calculated from the percentage of T-cell subsets as measured by flow cytometry and the absolute lymphocyte count provided by the central clinical laboratory. T-cell subsets were compared between clinical stages as documented in the patients' records. Patient numbers are indicated in the graphs.