Chronic lymphocytic leukemia B cells inhibit spontaneous Ig production by autologous bone marrow cells: role of CD95-CD95L interaction

A variable degree of humoral immunodeficiency is a common feature in patients with B-cell chronic lymphocytic leukemia (B-CLL). The aim of this study was to explore the possibility that B-CLL cells play a direct role in this phenomenon. To this end, patients' bone marrow (BM) immunoglobulin (Ig)-secreting cells were cocultured with autologous purified B-CLL cells. The results show that tumoral cells inhibited the spontaneous IgG secretion by BM plasma cells, and this effect increased after PMA-induction of B-CLL cells. This inhibitory process was proportional to the number of B-CLL cells added and depended on cellular contact. Adhesion molecules did not appear to be involved in the cellular interaction, because the inclusion of blocking antibody to a variety of these proteins did not reverse the inhibitory phenomenon. However, the addition of monoclonal antibody that blocked the function of either CD95 or CD95L clearly reversed B-CLL cell inhibition on autologous BM plasma cells. These latter cells were shown to express CD95, and B-CLL cells contained detectable quantities of CD95L at the level of messenger RNA and protein. Annexin V-binding experiments revealed increased apoptosis of BM Ig-secreting cells when cocultured with autologous B-CLL cells. Finally, this inhibitory phenomenon might be operative in vivo because (a) there was a good correlation between the intensity of the inhibitory effect in vitro and the serum IgG level exhibited by every patient and (b) B-CLL cells also inhibited in vivo antigen-induced IgG-tetanus toxoid-secreting cells obtained from normal immunized subjects. Collectively, these data suggest that B-CLL cells inhibit autologous CD95-bearing Ig-secreting cells by the interaction with CD95L present on B-CLL cells and, hence, contribute to the state of humoral immunodeficiency that occurs in these patients.

Juvenile chronic lymphocytic leukemia with unusual intracisternal inclusions: an ultrastructural study

The electron microscopic analysis of intracisternal inclusions in lymphocytes of the bone marrow and peripheral blood in a case of juvenile chronic lymphocytic leukemia is described. These inclusions consist of well-ordered microtubules attached to a central axis. The contribution of electron microscopic analysis in establishing the substructural pattern of these inclusions is discussed.

Circulating stem cell collection in lymphoma and myeloma after mobilization with cyclophosphamide and granulocyte colony-stimulating factor for autologous transplantation

We report the results of 72 leukapheresis procedures performed for autologous peripheral blood stem cell collection in 18 patients with lymphoma and myeloma, after combined mobilization with cyclophosphamide and granulocyte colony-stimulating factor (G-CSF). The numbers of mononuclear cells (MNCs), CD34+ cells and granulocyte-macrophage colony-forming units (CFU-GM) either in the peripheral circulation (preleukapheresis sample) or in the product obtained from leukapheresis (leukapheresis sample) were evaluated. A highly superior proportion of CD34+ cells (14-fold) and CFU-GM (5-fold) resulted from the mobilization therapy. CFU-GM and CD34+ cells were highly enriched with respect to all MNCs (relative recoveries: 2.13, range 0.3-41, and 1.08, range 0.2-8.5, respectively) due to an additional mobilization effect by the leukapheresis procedure. Also, a relatively strong linear correlation between the three different parameters was found in the leukapheresis product (CD34+:CFU-GM, r = 0.81; MNCs:CD34, r = 0.69; MNCs:CFU-GM, r = 0.75; CFU-GM:CD34+, and MNCs, r = 0.85). Our data suggest that the number of MNCs and CD34+ cells obtained after combined mobilization with cyclophosphamide and G-CSF can be used as predictor of the number of granulomonocytic progenitors.

Human tonsil, blood and bone marrow in vivo-induced B cells capable of spontaneous and high-rate immunoglobulin secretion in vitro: differences in the requirements for factors and for adherent and bone marrow stromal cells, as well as distinctive adhesion molecule expression

Human B cells capable of spontaneous IgG secretion are commonly found in circulation and in lymphoid tissues such as tonsil and bone marrow (BM). The present study compares the mechanisms that regulate tonsil, blood and BM B cells capable of spontaneous IgG secretion. The BM cell subset produced IgG during a markedly longer period of time (14 days) than did tonsil and blood cell subsets (2-3 days). Blood and BM, but not tonsil, B cell IgG secretion depended on the presence of adherent cells, as demonstrated by adherent cell depletion and re-addition experiments. Stromal BM cells supported linear IgG secretion by non-adherent BM cells for 2 weeks, but were unable to prolong the short-term IgG secretion by tonsil and blood cells. Different factors induced IgG secretion in each of the three B cell populations as optimal IgG secretion by tonsil, blood or BM cell subsets required either tumor necrosis factor-alpha, interleukin-6 or fibronectin + interleukin-6, respectively. Finally, these populations also showed differences in the expression of adhesion molecules; the tonsilar cell subset was PNA+/- CD44+ CD49d+ CD49e- Leu-8+/-, the blood cell subset was PNA- CD44+/- CD49d+ CD49e- Leu-8+ and the BM cell subset was PNA- CD44+/- CD49d+ CD49e- Leu-8-. These results suggest that the mechanisms controlling the final differentiation and the expression of adhesion molecules in these B lymphocytes exhibit territorial specificity.

Essential role of tumor necrosis factor-alpha in the differentiation of human tonsil in vivo induced B cells capable of spontaneous and high-rate immunoglobulin secretion

Human tonsils contain B cells capable of spontaneous and high-rate immunoglobulin (Ig) secretion in vitro. These cells are in vivo induced mature B cells, and, as such, they provide and adequate model for studying tonsil B cell differentiation. The present report analyzes the effect of a variety of factors on purified tonsil B cells capable of spontaneous IgG secretion in fetal calf serum (FCS)-containing and serum-free supplemented cultures. Tumor necrosis factor-(TNF) alpha was found to be important for these B cells to reach the high-rate IgG-secreting stage, as is indicated by the following findings: (a) none of the factors used modified tonsil B cell IgG secretion in FCS-containing cultures; (b) TNF-alpha (5-20 ng/ml), but not other cytokines or factors including interleukin (IL)-6, was capable of restoring missing IgG production in serum-free supplemented cultures of tonsil B cells; and (c) IgG secretion in FCS-containing cultures was inhibited by the addition of blocking anti-TNF-alpha antibodies, but not anti-IL-6 antibodies, and this inhibition could be specifically reversed by exogenous TNF-alpha. TNF-alpha was actively produced by tonsil B cells (range 120-750 pg/ml) in the presence, but not in the absence, of FCS. The TNF-alpha inductive effect occurred during the first 12 h of culture and did not require DNA synthesis. These results indicate that the early and endogenous generation of TNF-alpha seems to be essential for tonsil in vivo induced B cells to differentiate into the high-rate Ig-secreting stage.

Amylase-producing Bence Jones multiple myeloma with pancreatitis-like symptoms

Amylase-producing tumors are mainly adenocarcinomas and, in rare instances, multiple myelomas. We describe here a first case of amylase-producing Bence Jones type myeloma with pancreatitis-like symptoms and the second in a Caucasian patient. The finding of salivary-type hyperamylasemia in a 72-year-old female with a possible pancreatitis made us suspect the diagnosis. Amylase production was observed in bone marrow cultures in which 96% of cellularity was composed of plasmablasts. Serum amylase level decreased when chemotherapy was given.

Cytokine network regulating terminal maturation of human bone marrow B cells capable of spontaneous and high rate Ig secretion in vitro

Human bone marrow (BM) B cells capable of spontaneous and high rate Ig secretion for 14 days in vitro have been described previously. We have shown recently that Ig secretion by these BM cells depends on stromal adherent BM cell-derived factors identified as IL-6 and fibronectin. Our report shows that the endogenous generation of IL-1 beta and TNF-alpha in serum-containing cultures of BM mononuclear cells (BMMC) is also involved in the control of Ig-secreting cells, because their blockade with specific antibodies markedly reduced Ig production. Further experiments revealed that IL-1 beta and TNF-alpha acted by regulating IL-6 production, as can be deduced from the following findings: 1) the inhibition of Ig secretion caused by either anti-IL-1 beta or anti-TNF-alpha antibodies could be reversed by exogenous IL-6; 2) the addition of either of these antibodies inhibited endogenous IL-6 production in BMMC cultures; 3) IL-1 beta plus TNF-alpha, but neither one alone, restored complete IL-6 and Ig production by BMMC in serum-free cultures. Moreover, adherent, but not nonadherent, BM cells were responsible for endogenous IL-1 beta and TNF-alpha secretion. Finally, IL-1 beta plus TNF-alpha induced the production of IL-6, but not of Ig, by adherent BM cells. Neither IL-6 nor Ig production was induced by adding this cytokine combination to nonadherent BM cell cultures, despite the fact that this fraction contained all the Ig-secreting cells. However, the addition of IL-6 restored Ig secretion in this cell fraction. These results suggest that IL-1 beta and TNF-alpha produced by adherent BM cells synergistically induce early IL-6 generation, which, in turn, drives BM B cell producers into the high rate Ig-secreting state.

Cytokine network regulating terminal maturation of human bone marrow B cells capable of spontaneous and high rate Ig secretion in vitro

Human bone marrow (BM) B cells capable of spontaneous and high rate Ig secretion for 14 days in vitro have been described previously. We have shown recently that Ig secretion by these BM cells depends on stromal adherent BM cell-derived factors identified as IL-6 and fibronectin. Our report shows that the endogenous generation of IL-1 beta and TNF-alpha in serum-containing cultures of BM mononuclear cells (BMMC) is also involved in the control of Ig-secreting cells, because their blockade with specific antibodies markedly reduced Ig production. Further experiments revealed that IL-1 beta and TNF-alpha acted by regulating IL-6 production, as can be deduced from the following findings: 1) the inhibition of Ig secretion caused by either anti-IL-1 beta or anti-TNF-alpha antibodies could be reversed by exogenous IL-6; 2) the addition of either of these antibodies inhibited endogenous IL-6 production in BMMC cultures; 3) IL-1 beta plus TNF-alpha, but neither one alone, restored complete IL-6 and Ig production by BMMC in serum-free cultures. Moreover, adherent, but not nonadherent, BM cells were responsible for endogenous IL-1 beta and TNF-alpha secretion. Finally, IL-1 beta plus TNF-alpha induced the production of IL-6, but not of Ig, by adherent BM cells. Neither IL-6 nor Ig production was induced by adding this cytokine combination to nonadherent BM cell cultures, despite the fact that this fraction contained all the Ig-secreting cells. However, the addition of IL-6 restored Ig secretion in this cell fraction. These results suggest that IL-1 beta and TNF-alpha produced by adherent BM cells synergistically induce early IL-6 generation, which, in turn, drives BM B cell producers into the high rate Ig-secreting state.