HUMAN-BONE MARROW AND PERIPHERAL-BLOOD LYMPHOCYTE-T DEPLETION - EFFICACY AND EFFECTS OF BOTH T-CELLS AND MONOCYTES ON GROWTH OF HEMATOPOIETIC PROGENITORS

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  • 1 January 1985
    • journal article
    • research article
    • Vol. 65  (3) , 663-679
Abstract
The efficacy of 4 separate methods of human bone marrow T lymphocyte depletion was assessed, and the effect of T cells and monocytes on in vitro growth of marrow (CFU-GEMM [granulocytic, erythrocytic, monocytic and megakaryocytic colony forming unit] BFU-E [erythroid burst forming unit] and CFU-GM [granulocytic-macrophage colony forming unit]) and peripheral blood (BFU-E) hematopoietic progenitors was determined. Extent of T cell depletion was assessed by multiparameter fluorescent cell sorter (FACS) analysis and by functional studies. Cells staining positively by FACS analysis for 1 or more of 3 separate fluorescent pan-T cell monoclonal antibodies (MCAbs) comprised 8.4% to 9.5% of control marrow mononuclear cells (MNC). T cells constituted 3.2-5.1% of marrow following single, sequential, or combination treatment with 2 different pan-T cell MCAbs (Leu 1 and TM1) plus complement, 1.5-2.2% of marrow following solid-phase immunoabsorption (panning), 0.2% of marrow after sheep cell rosetting, and only 0.05% of marrow after FACS selective cell sorting and gated separation. T cells made up 59%-73% of control peripheral blood MNC and 0.8%-2.8% of peripheral MNC following sheep cell rosetting plus treatment with Leu 1 MCAb and complement. Mitogen (PHA [phytohemagglutinin], Con A [concanavalin A]) and allogeneic MLC-induced blastogenic response (stimulation indices, experimental/control or E/C) revealed a concordant decrement in marrow T cell function after MCAb plus complement (E/C of 3.9 to 9.0), after panning (E/C of 1.6 to 3.5) and after sheep cell rosetting (E/C of 0.7-1.3), compared with control marrow (E/C of 5.3-15.7). After T cell depletion, marrow BFU-E growth was 95-120% of control, CFU-GM growth was 90-108% of control, and CFU-GEMM growth was 89-111% of control. Marrow T cell and/or monocyte depletion did not alter erythropoietin-dependent BFU-E growth in the absence of Mo-conditioned medium (81-95% of control), and the addition of as many as 50-100 .times. 103 purified marrow monocytes or T cells to 105 autologous nonadherent T cell-depleted marrow target cells had a negligible (P > 0.1) effect on marrow BFU-E growth in vitro. Peripheral blood (PB) BFU-E/105 T-depleted target cells were 106% .+-. 19% of expected; PB BFU-E growth was significantly diminished after monocyte depletion alone (7% .+-. 6% of expected) or after monocyte plus T cell depletion (8% .+-. 4% of expected). Addition of as many as 150 x 103 T cells to 105 autologous nonadherent T cell-depleted PB null cells produced only small (18-30% of expected) increments in BFU-E growth, whereas addition of autologous monocytes to null target cells restored PB BFU-E growth to 82-94% of expected. It was concluded that T lymphocyte depletion does not appreciably alter in vitro growth of human marrow (BFU-E and CFU-GM) or PB (BFU-E) hematopoietic progenitors; that monocytes are a major source of burst-promoting activity for PB but not marrow BFU-E erythropoietin-dependent differentiation; and that functional and immunologic marrow T-cell depletion is more effectively achieved with panning, sheep cell rosetting, or gated FACS separation, rather than by treatment with pan-T cell (Leu 1, TM1) MCAb plus complement.