In vitro maturation of B cells in chronic lymphocytic leukemia. I. Synergistic action of phorbol ester and interleukin 2 in the induction of Tac antigen expression and interleukin 2 responsiveness in leukemic B cells.
Recent evidence indicates that interleukin 2 (IL 2), formerly thought to serve as growth factor exclusively for activated T cells, is directly involved in human B cell differentiation. We have investigated the role of IL 2 and IL 2 receptors (as defined by monoclonal anti-Tac antibody) in the phorbol ester-induced in vitro maturation of leukemic B cells from patients with chronic lymphocytic leukemia (CLL). Peripheral blood lymphocytes from B cells from CLL patients with high (greater than 10(5)/microliters) white blood cell counts were depleted of residual T lymphocytes and low-density cells (primarily macrophages) by consecutive steps of E rosetting, complement-mediated lysis of OKT3+ and OKT4+ cells, and Percoll density gradient centrifugation. No OKT3+ T cells were detectable in these cell populations before or after culture. When incubated for 3 days with phorbol ester plus recombinant human IL 2 (rIL 2), 12 to 57% of highly purified B cells from four of five tested patients expressed Tac antigen. Both phorbol ester and rIL 2 were required for maximal Tac antigen expression. Functional studies revealed that phorbol ester-activated (but not resting) CLL B cells responded to rIL 2 with [3H]thymidine incorporation and with enhanced secretion of IgM. Tac+ B cells were isolated in two cases on a fluorescence-activated cell sorter. In one patient, stimulation of Tac+ B cells with rIL 2 resulted in enhanced [3H]thymidine incorporation but no change in IgM secretion, as compared with Tac- B cells; in the second patient, stimulation of Tac+ B cells with rIL 2 did not result in [3H]thymidine uptake, but did result in significant IgM secretion. These findings indicate that certain leukemic B lymphocytes can be induced to express IL 2 receptors and respond to IL 2. The use of resting clonal B cell populations arrested at distinct stages of differentiation may help to better define the stage(s) at which IL 2 acts directly on B cells to induce proliferation and/or terminal differentiation.
Kabelitz
D
D
Pfeffer
K
K
von Steldern
D
D
Bartmann
P
P
Brudler
O
O
Nerl
C
C
Wagner
H
H
D000911:Antibodies, Monoclonal / Q000502:physiology; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation; D004357:Drug Synergism; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D007945:Leukemia, Lymphoid / Q000276:immunology* / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects; D010704:Phorbols / Q000494:pharmacology*; D011971:Receptors, Immunologic / Q000096:biosynthesis; D015375:Receptors, Interleukin-2; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D007376:Interleukin-2; D010704:Phorbols; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D013755:Tetradecanoylphorbol Acetate