Transforming growth factor beta is a potent inhibitor of interleukin 1 (IL-1) receptor expression: proposed mechanism of inhibition of IL-1 action.

Transforming growth factor beta (TGF-beta) acts as a potent inhibitor of the growth and functions of lymphoid and hemopoietic progenitor cells. Cell proliferation depends not only on the presence of growth factors, but also on the development of specific receptor-signal transducing complexes. We therefore investigated whether the inhibitory actions of TGF-beta could be mediated by inhibition of growth factor receptors. TGF-beta inhibited the constitutive level of interleukin 1 receptor (IL-1R) expression on several murine lymphoid and myeloid progenitor cell lines, as well as IL-1R expression induced by interleukin 3 (IL-3) on normal murine and human bone marrow cells. Furthermore, treatment of bone marrow progenitor cells with TGF-beta concomitantly inhibited the ability of IL-1 to promote high proliferative potential (HPP) colony formation as well as blocked IL-1-induced IL-2 production by EL-4 6.1 cells. These findings provide the first evidence that the inhibitory action of TGF-beta on the growth and functional activities of hematopoietic and T cells is associated with a reduction in the cell surface receptor expression for IL-1.

A region of the Herpesvirus saimiri genome required for oncogenicity.

Herpesvirus saimiri naturally infects squirrel monkeys (Saimiri sciureus) without producing signs of disease; infection of other New World primates, however, results in a rapidly progressing, malignant, T-cell lymphoma. Results described in this report identify a region of the viral genome that is required for oncogenicity in owl monkeys (Aotus trivirgatus); this region is not required for replication of the virus. This is believed to be the first such genomic region identified in a herpesvirus system.

Attenuation of herpesvirus saimiri for marmosets after successive passage in cell culture at 39 degrees C.

A variant of Herpesvirus saimiri (HVS) stably attenuated for marmosets was isolated after serial passage of wild-type HVS in cell culture at 39 degrees C. Marmosets previously inoculated with attenuated virus experienced a significant delay in the development of lymphoma when challenged with wild-type HVS.

Mononuclear cell fraction carrying Herpesvirus saimiri in persistently infected squirrel monkeys.

Circulating lymphocytes from squirrel monkeys persistently infected with Herpesvirus saimiri (HVS) were separated into B- and T-lymphocyte fractions by a rosette-enrichment technique. HVS was isolated only from lymphocyte fractions forming rosettes or from unseparated lymphocytes; this indicated that T-lymphocytes were the target cells for HVS in the natural host, squirrel monkeys.

Susceptibility of common marmosets (Callithrix jacchus) to oncogenic and attenuated strains of Herpesvirus saimiri.

Adult common marmosets, inoculated with either of 2 oncogenic Herpesvirus saimiri (HVS) strains, developed fatal lymphoproliferative disease within 23-25 days post inoculation (PI). The disease was identical to HVS-induced lymphoma in cotton-topped and white-lipped marmosets. Common marmosets inoculated with an attenuated HVS strain developed persistent infection; virus has been recovered from cocultivated lymphocytes of these animals for more than 384 days PI.

Granulocyte-macrophage colony stimulating factor (GM-CSF) and macrophage colony stimulating factor (CSF-1) synergize to stimulate progenitor cells with high proliferative potential.

The ability to expand a population of bone marrow progenitors capable of forming macrophage colonies of high proliferative potential (HPP-CFC) was achieved using a culture system and signal requirements not previously shown to support the growth of HPP-CFC. Using bone marrow cells from untreated animals (not 5-FU-treated), culture conditions designed primarily for the detection of GM-CFC or M-CFC progenitors, and a more stringent criteria for HPP-CFC colony size (greater than or equal to 2 mm diameter), HPP-CFC progenitor expansion was demonstrated following simultaneous addition of rGM-CSF and CSF-1 to bone marrow cultures. Examination of the sequence and temporal requirements for rGM-CSF and CSF-1 addition necessary for the development of HPP-CFC-like colonies revealed that addition of the second factor could be delayed for up to 5 days and still result in the development of significant numbers of HPP-CFC colonies. Based on a comparison with human spleen cell conditioned medium (HSCM) and interleukin 1 (rIL 1), as sources of "synergistic activity" (SA) for the development of HPP-CFC-like colonies in combination with CSF-1, the combination of GM-CSF and CSF-1 appears to represent a novel pathway for stimulating the expansion of HPP-CFC progenitors with high proliferative potential.

Differential production of IFN-alpha/beta by CSF-1- and GM-CSF-derived macrophages.

Mature macrophages, derived in vitro from bone marrow progenitors under the influence of either macrophage colony stimulating factor (CSF-1) or granulocyte-macrophage (GM)-CSF, have been shown to differ morphologically and functionally. The data presented in this report demonstrate that macrophages derived from bone marrow progenitors under the influence of CSF-1 are highly resistant to infection with vesicular stomatitis virus (VSV), and that this refractoriness can be reversed by treatment of cells with anti-IFN-alpha/beta antibody. In contrast, macrophages derived from bone marrow progenitors under the influence of GM-CSF are highly susceptible to the cytopathic effects of VSV, but can be protected by very low concentrations of exogenous IFN-alpha/beta. These findings suggest that CSF-1 derived macrophages have a greater capacity for the production and/or utilization of IFN-alpha/beta than GM-CSF-derived macrophages, which may account for many of the differentiative differences reported previously.

Comparison of bone marrow progenitors responsive to granulocyte-macrophage colony stimulating factor and macrophage colony stimulating factor-1.

The responsiveness of bone marrow progenitors (BMP) from C3H mice to highly purified or recombinant preparations of Macrophage Colony-Stimulating Factor-1 (CSF-1) and Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) was compared by counting the number of colonies (greater than or equal to 50 cells) after 10 days in culture with CSF. Cells responsive to CSF-1 or GM-CSF exhibited maximum colony formation over a wide dose range, although GM-CSF supported colony formation at lower concentrations. The response of BMP to optimal concentrations of CSF-1 was greater than or equal to 5 times greater than the response of BMP to GM-CSF. Analysis of the kinetics of colony formation revealed that, at day 5, the number of BMP responsive to GM-CSF or CSF-1 was approximately equal; the number of CSF-1 colonies increased significantly through day 10, while those cultured in GM-CSF did not. The response of BMP to CSF-1 and GM-CSF was also studied in liquid culture; the differences in yield of mature macrophages was consistent with the differences observed in agar culture. Although both cell populations were shown to be 100% mononuclear by day 7, Coulter Channelyzer analysis of these mature macrophages showed marked differences in cell size distribution. By day 7, cells grown in CSF-1 resulted in a homogeneous population of large cells, whereas GM-CSF cultures showed a heterogeneous distribution. Finally, CSF-1-derived cells possessed increased nonspecific and specific phagocytic capabilities when compared to GM-CSF-derived macrophages. These findings indicate that the actions of GM-CSF and CSF-1 upon the bone marrow compartment results in the generation of mature macrophages which differ morphologically and functionally and may account for the heterogeneity in macrophage populations.

Bone marrow progenitors cultured in the presence of granulocyte-macrophage colony-stimulating factor versus macrophage colony-stimulating factor differentiate into macrophages with distinct tumoricidal capacities.

Bone marrow-derived cells from C3H/HeJ mice were cultured in the presence of recombinant murine granulocyte-macrophage colony-stimulating factor (rGM-CSF) or highly purified murine macrophage colony-stimulating factor (CSF-1) for 7 days. Following this 7-day culture period, mature macrophages were harvested and replated at precise densities in the absence of exogenous rGM-CSF or CSF-1, and assayed in a two-signal tumoricidal assay. Cultures were stimulated with medium only or with combinations of recombinant interferon-gamma (rIFN-gamma) as the "priming" signal, and/or butanol-extracted lipopolysaccharide (But-LPS) as the "triggering" signal for 24 hr. At this time, 51Cr-labeled, P815 tumor target cells were added, and the percent tumor cell cytotoxicity was determined after 16 hr. Macrophages derived under the influence of rGM-CSF exhibited significant tumoricidal capacity with medium alone (16 +/- 5%). The addition of "priming" signal only (i.e., rIFN-gamma, 10.0 U/ml) significantly increased tumoricidal capacity to 31 +/- 9%. Treatment with But-LPS alone did not alter the basal tumoricidal activity of rGM-CSF-derived macrophages. Combinations of rIFN-gamma (10.0 U/ml) and But-LPS (0.5-5.0 micrograms/ml) generated highly tumoricidal macrophages (50-60% tumor cell cytotoxicity). In contrast, medium-treated CSF-1-derived macrophages exhibited a significantly lower basal level of tumor cytotoxicity (6 +/- 3%). Unlike rGM-CSF-derived macrophages, treatment of CSF-1-derived macrophages with high concentrations of rIFN-gamma alone did not increase significantly the level of cytotoxicity above that of medium-treated cultures. However, CSF-1-derived macrophages responded to the highest concentrations of But-LPS (5.0 micrograms/ml) to increase tumoricidal activity from 6 +/- 3% to 17 +/- 5%. Optimal tumoricidal activity (44 +/- 17%) was observed when CSF-1-derived macrophages were treated simultaneously with high concentrations of both rIFN-gamma and But-LPS. Thus, macrophages derived from bone marrow progenitors in either rGM-CSF or CSF-1 exhibited tumoricidal capacities that differed in basal activity as well as in their requirements for and sensitivities to "priming" and "triggering" signals.

Correlation of enzyme-linked immunosorbent assays for serum human immunodeficiency virus antigen and antibodies to recombinant viral proteins with subsequent clinical outcomes in a cohort of asymptomatic homosexual men.

A cohort of asymptomatic homosexual men at a Boston community health center was screened for the presence of human immunodeficiency virus (HIV) serum antigen and antibodies to recombinant proteins containing portions of the envelope and the gag (core) gene products. Of 196 asymptomatic men screened, 149 were antigen-negative/antibody-negative, 41 were antigen-negative/antibody-positive, and six were antigen-positive/antibody-positive. All three men in whom the acquired immune deficiency syndrome (AIDS) developed over the next year were antigen-positive at enrollment. Although a larger portion of the men who were antigen-positive and did not demonstrate progression to AIDS after one year had thrush, zoster, or generalized lymphadenopathy, the associations were not statistically significant. Whereas all of the seropositive men had antibody to viral envelope antigens, about a quarter did not have detectable antibodies to recombinant core antigens. However, all of these men had detectable antibody to core antigens by Western blot. Titers to recombinant core and envelope antigens tended to be lower in the men with AIDS. HIV-infected persons who are more likely to have enhanced immuno-compromise may be identified by these newer tests, but further longitudinal studies will be necessary to fully understand their prognostic value.

Recombinant bacillus Calmette-Guérin as a potential vector for preventive HIV type 1 vaccines.

In August 1997, the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) convened an expert working group to discuss current strategies for the development of HIV type 1 vaccines. Based on the recent findings of investigators from Japan's National Institute of Infectious Diseases (NIID) in Tokyo using recombinant bacillus Calmette-Guérin (rBCG) as a potential vectored vaccine for HIV, a recommendation was made that further work in this area is a priority. As a result, the working group reconvened in September 1998 to discuss the progress to date with this vaccine approach, as well as areas of related research to assess the feasibility of a BCG-vectored HIV vaccine. This report summarizes the discussions addressing the available scientific data on the potential use of rBCG as a vector for preventive HIV vaccines, the work necessary to move such candidate vaccines into Phase 1 clinical trials, and recommendations targeted at facilitating the long-term development of rBCG-vectored HIV vaccines.

Human T-cell leukemia virus: transformation in vitro of nonhuman primate T-lymphocytes and experimental inoculation of nonhuman primates.

T-lymphocytes from three species of New World monkeys were susceptible to transformation in vitro with human T-cell leukemia virus. Marmoset T-lymphocytes transformed in vitro with HVS or HVA, T-lymphotropic herpesviruses of New World monkeys, were also transformed with HTLV resulting in doubly transformed T-cells. This finding may provide a potential model for investigating the possible interaction between a herpesvirus and T-lymphotropic retroviruses in the clinical condition AIDS.

[Lymphocyte heterogeneity of the T system: characterization of an allotypic antiserum recognizing a sub-species antigenic determinant in non-human primates]. / Heterogeneidad linfocitaria del sistema T: caracterización de un antisuero alotípico que reconoce un determinante antigénico de sub-especie en primates no-humanos.

To determine the membrane properties in T-lymphocyte population from Saguinus primates or lymphoblastoid cell lines of the same origin, an allotypic antiserum was prepared inoculating two Saguinus illigeri with 3.5 x 10(10) viable 70N2 cells obtained in-vitro, from a lymphoma induced by inoculation of Herpesvirus Saimiri in a Saguinus oedipus. The 70N2 cells carried the virus genome in an episomal way; it did not produce infectious virus and it formed spontaneous rosettes (99%) with sheep erythrocytes. The resulting allotypic antiserum inhibited the formation of E rosettes and specifically reacted with lymphoblastic T-cell lines and peripheral lymphocytes of Saguinus oedipus while it did not cross react with these cells or peripheral lymphocytes of S. illigeri or nigrifons, S. jacchus, Saimiri sciureus , Papio Sp. and human primates. These results show that two antigenic populations exist within Saguinus T-lymphocytes; one is common to all members of the species and the other is specific for subspecies related to the spontaneous rosette receptors and it is present in lymphoblastic cell lines-T of the same origin.