Surface Immunoglobulin Density on Human Peripheral Blood Mononuclear Cells

Abstract

AbstractThe densities of surface immunoglobulin (sIg) on peripheral blood mononuclear cells (PBM) of normals and patients with chronic lymphocytic leukemia (CLL), chronic lymphosarcoma cell leukemia (LCD, and hairy cell leukemia (HCL) were analyzed using the fluorescence-activated cell sorter (FACS). PBM were labeled with fluorescein conjugates of F(ab')2 fragments of affinity chromatography-purified anti-Fab or class-specific anti-µ, anti-δ, anti-γ, or anti-α. Histograms of relative cell fluorescence, reflecting sIg density, were prepared with the FACS. Anti-Fab-labeled normal PBM demonstrated a homogeneous low-density peak that when separated by the FACS and analyzed cytochemically consisted predominantly of monocytes, whereas brighter-staining cells were predominantly lymphocytes. Anti-µ and anti-δ labeled 9.0% and 8.5% of normal PBM, respectively, the sIg+ cells being virtually all lymphocytes. Cells labeled by anti-γ exhibited low homoge neous sIg density and consisted of more than 80% monocytes. No normal or leukemic PBM were labeled by anti-α. All sIg-positive cells (<5% monocytes) from 12 of 13 patients with CLL had very low homogeneous densities of sIg and bore sIgM, whereas cells from 9 of 13 and 2 of 13 patients bore sIgD and sIgG, respectively. Similarly, PBM from 2 patients with HCL exhibited low and homogeneous densities of sIgM, sIgD, and sIgG, whereas those from a third patient bore only sIgG. By contrast, the density of sIgM and PBM derived from 3 patients with LCL was very high; sIgD and sIgG densities varied from very high to undetectable in these patients. The different homogeneous densities of sIg on peripheral blood lymphocytes from patients with CLL, HCL, and LCL suggest that these diseases represent malignant transformation of different B-lymphocyte subpopulations.