In vitro effects of recombinant TNF-alpha binding protein (rTBP-1) on hematopoiesis of HIV-infected patients.

Tumor necrosis factor-alpha (TNF-alpha) is believed to contribute to the hematopoietic failure often observed in patients with AIDS. Soluble TNF receptors (sTNFR) compete for TNF-alpha with cell surface receptors and thus may block its activity. The effect of the p55 sTNFR (recombinant TNF-binding protein-1 [rTBP-1]) on the clonogenic growth of hematopoietic progenitor cells from 27 HIV-infected patients was evaluated in comparison with 11 normal study subjects. Peripheral blood-derived, myelopoietic (i.e., granulomonocytic colony-forming cells [GM-CFC]) and erythropoietic (i.e, burst-forming unit, erythroid [BFU-E]) colonies were grown in 10-day semisolid cultures with increasing concentrations of rTBP-1. Significantly, dose-dependent increases occurred in GM-CFC from 17 of 21 AIDS patients and 12 of 21 in BFU-E at rTBP-1 concentrations of 1microg/ml to 25 microg/ml. In contrast, rTBP-1 failed to induce any appreciably increased colony formation in normal cell cultures. In 6 patients treated with highly active antiretroviral treatment (HAART), TBP-1 alone did not demonstrate the in vitro hematopoiesis-enhancing effect. This study may provide an initial step in development of therapeutic use of TBP as a TNF-alpha antagonist in HIV-infected patients who do not benefit sufficiently from antiretroviral treatment, and in other conditions in which increased levels of TNF-alpha may contribute to hematopoietic deficiencies.

Defective in vitro granulopoiesis in patients with anorexia nervosa.

Patients with anorexia nervosa (AN) frequently suffer from a mild degree of anemia and from moderate leukopenia on top of their undernourished state and metabolic disarrangements. To evaluate in vitro granulopoiesis and its relationship to cytokine production and undernutrition, we have studied 10 adolescent girls with moderate AN (age range, 13.5-18.0). Study methods included assessment of peripheral blood (PB) granulocyte-macrophage colony-forming cells (GM-CFC) of the patients and age-matched controls, and determination of plasma and conditioned medium (CM) of mononuclear cells levels of IL-1, IL-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor (TNF), all of which may play a role in GM-CFC growth regulation. GM-CFC numbers were significantly lower in AN patients compared with the normal controls (13.09 +/- 11.15 versus 39.33 +/- 26.61 colonies/5 x 10(5) cells, p < 0.01). No inhibitory effect was found in either plasma or CM of patients with AN. However, when CM were applied to non-recombinant human GM-CSF-stimulated normal bone marrow GM-CFC targets, the number of colonies stimulated by the CM of patients with AN was significantly lower than those stimulated by the CM of the controls (73.5 +/- 20.1 versus 113.0 +/- 11.6, p < 0.025). GM-CSF concentrations in CM were significantly lower in patients with AN compared with normal controls, but no such differences were found in IL-1, IL-3, IL-6, or TNF concentrations. These results indicate defective in vitro granulopoiesis in AN patients, manifested by a reduction of both GM-CFC and GM-CSF. It has to be determined whether these changes are the result of the basic disease process or are they due to malnutrition.

Control of neuroblastoma cell proliferation and differentiation by human bone marrow.

BACKGROUND: Neuroblastoma (NB) is one of the few tumors known to undergo spontaneous regression. Its progression, however, often leads to bone marrow (BM) metastasis. Proliferation and differentiation of human NB cells may be regulated in vitro by a variety of biologic agents, some of which are released by low-density BM and peripheral blood (PB) cells. Little is known regarding BM cell-derived control of NB cell growth and differentiation. METHODS: The proliferative and differentiative responses of NB cells, to BM cell-, and to PB cell-derived conditioned medium (CM) were evaluated in comparison to cytokine-induced responses. RESULTS: CM from unstimulated cultures of low density BM and PB cells, from healthy donors, from newborn infants, and from NB patients, significantly and reproducibly stimulate NB cell growth in vitro. The intensity of CM-induced stimulation was not attained by recombinant human tumor necrosis factor (rhTNF), interferon (rhIFN), or granulocyte-monocyte colony stimulating factor (rhGM-CSF); and although epidermal growth factor (rhEGF) and transforming growth factor alpha (rhTGF alpha) were strongly stimulatory, neutralizing antibodies against each of these agents did not affect CM-derived activity. In contrast to growth stimulation, differentiation of CM-treated NB cells, was reproducibly suppressed, as reflected in abrogation of neuronal cell morphology as well as of neurofilament and neuron specific enolase expression. CONCLUSIONS: Spontaneous regression of NB tumors, on one hand and BM metastasis on the other may be associated with the extent and nature of the NB cell response to regulatory activity released by BM and PB cells.

Ciprofloxacin inhibits human hematopoietic cell growth: synergism with tumor necrosis factor and interferon.

The cytokines tumor necrosis factor (TNF) and interferon (IFN) induce antiproliferative and cytotoxic activity in a variety of cell types. Ciprofloxacin (CFN)--a new fluoroquinolone antibiotic--has also been described, at high concentrations, to suppress hematopoietic cell growth and to affect cytokine production. This study examines the possible relationship between TNF alpha and IFN gamma, as components of host defense mechanisms, and CFN. To investigate the effect of CFN, either alone or combined with TNF or IFN, on normal human hematopoiesis, we examined in vitro changes in hematopoietic progenitor cell growth. We also studied the effect of CFN on human cytokine production by determining TNF, IFN, and colony-stimulating factor (CSF) production by human mononuclear leukocytes (MNC). Granulocyte and monocyte colony formation (granulocyte-macrophage colony-forming cells, GM-CFC) as well as erythroid burst formation (erythroid burst-forming units, BFU-E) were inhibited only by high nontherapeutic levels of CFN. Lower CFN concentrations, however, were inhibitory in the presence of low, noninhibitory concentrations of human recombinant (r)IFN gamma or rTNF alpha. CFN induced a striking dose-dependent increase in IFN gamma production and a decrease in CSF production by mitogen-stimulated MNC. No effect was observed, however, on TNF production by stimulated MNC. The synergistic inhibition of hematopoietic progenitor cell proliferation, achieved by combining low doses of CFN and of antiproliferative cytokines, may explain the occasional case of leukopenia or anemia observed in infected patients receiving CFN. This effect may also indicate the applicability of such a combination against malignant cell growth.