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M Baccarini

Publications and source records attributed to M Baccarini.

At least 55 records · Page 3Linked to original sources
PubMed1989

Efficient natural defense mechanisms against Listeria monocytogenes in T and B cell-deficient allogeneic bone marrow radiation chimeras. Preactivated macrophages are the main effector cells in an early phase after bone marrow transfer.

Radiation chimeras in the early phase after bone marrow transplantation are a good model to study the efficiency of the body's nonspecific defense system represented by macrophages (M phi), polymorphonuclear cells (PMN), and NK cells. These cell types are present in large numbers in spleen and liver at that time, whereas the specific immune system represented by T and B cells is functionally deficient. We previously reported enhanced activities in vitro of M phi (and PMN) from recipient animals in an early phase after allogeneic bone marrow transfer. We here demonstrate that these activities result in enhanced spontaneous resistance against Listeria monocytogenes in vivo: CFU of L. monocytogenes in spleen and liver 48 h after infection were about 1 or 2 to 4 log steps less than in untreated control mice of donor or host haplotype. This enhanced resistance decreased over the 4-mo period after marrow transfer. Preactivated M phi were identified as the most important effector cells. Isolated from spleen and peritoneal cavity, they performed enhanced killing of phagocytosed Listeria. Such preactivated M phi occurred in recipient animals after transfer of allogeneic but not of syngeneic bone marrow. The precise mechanism of M phi activation in the allogeneic radiation chimera in the complete absence of any detectable T cell function is not clear at present. However, these preactivated M phi display an important protective effect against L. monocytogenes: chimeras could eliminate Listeria without acquisition of positive delayed-type sensitivity when infected with 10(3) bacteria. An inoculum of 5 . 10(3) L. monocytogenes resulted either in prolonged survival compared with normal mice of the recipient haplotype or in definitive survival accompanied by a positive delayed-type sensitivity. We concluded that enhanced nonspecific immune functions can in part compensate for the defective specific immune system after bone marrow transfer.

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PubMed1989

Functional heterogeneity of macrophage precursor cells from spleen of Leishmania donovani-infected and untreated mice.

We recently described the bone marrow-derived macrophage precursor, which is able to spontaneously and extracellularly kill protozoa of the genus Leishmania. These nonadherent, nonphagocytic macrophage precursor cells are present in the spleen of healthy mice only in a small quantity. However, high numbers of proliferating macrophage precursors are isolated from the spleen of Leishmania donovani-infected mice. Macrophage precursors from spleens of diseased animals are able to kill spontaneously the promastigote as well as the amastigote form of L. donovani. The mechanism of the spontaneous leishmanicidal activity of macrophage precursor cells derived from spleens of L. donovani-infected mice was investigated. This effector function could be defined in part as an antibody-dependent cellular cytotoxicity. In addition we assessed the role of CSF-1-containing L cell-conditioned supernatant at the leishmanicidal activity of these immature cells of the macrophage lineage. For that purpose, nonadherent spleen cells from healthy mice were cocultivated with this CSF-1-containing medium for 4 days. These in vitro proliferated macrophage precursor cells from untreated mice showed an increased leishmanicidal activity. Thereby we established a further activation mechanism for proliferating splenic macrophage precursor cells responsible for the observed killing of L. donovani pro- and amastigotes. The spontaneous cytotoxicity of macrophage precursors from spleens of L. donovani-diseased animals is thus defined as a cooperative effect of antibody-dependent cellular cytotoxicity and Macrophage-CSF activation.

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PubMed1989

Cooperative effects of colony-stimulating factor 1 and recombinant interleukin 2 on proliferation and induction of cytotoxicity of macrophage precursors generated from mouse bone marrow cell cultures.

Precursor cells for NK activity, present in the light fraction of fresh mouse bone marrow, were cultivated in vitro in the presence of either CSF-1, IL-2, or a combination of both factors. In the presence of only CSF-1, strong proliferation was induced. Cells quickly passed the macrophage precursor stage and matured to typical macrophages. Neither granula formation nor NK activity were induced. Under culture conditions with only IL-2 NK activity had developed after 3 d, however, no significant proliferation occurred. In the presence of both factors strong proliferation was induced, and concomitantly, granula formation and NK activity developed. Apparently, proliferation depended on CSF-1 and granula formation, and NK cytotoxicity was induced by IL-2. When proliferating cells with strong anti-YAC-1 activity from a culture in CSF-1 plus IL-2 were further cultivated in only IL-2, the content of granula further increased, whereas proliferation gradually stopped. In contrast, when these cells from CSF-1 plus IL-2 culture were further cultivated in only CSF-1, granula disappeared and NK activity was lost, whereas sustained proliferation and differentiation to macrophages occurred. Only under culture conditions with both factors were proliferation and NK activity both maintained. More than 90% of cells from a 3-d culture in CSF-1 plus IL-2 expressed the NK 1.1. marker, whereas F4/80 was only marginally detected by FACS analysis. After two further days in culture, 70% of the cells expressed F4/80 and 60% coexpressed NK 1.1. and F4/80. By setting the size scatter in order to gate for large granular cells, a population was obtained with 100% coexpression of NK1.1. and F4/80. The data indicate that early cells of the macrophage lineage can develop into different functional and morphological directions depending on the varying influence of IL-2 and CSF-1.

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PubMed1989

Effect of human recombinant IL-2 on murine macrophage precursors. Involvement of a receptor distinct from the p55 (Tac) protein.

Homogeneous populations of bone marrow-derived murine macrophage precursors are able to respond to human rIL-2. A prolonged exposure to the lymphokine results in proliferation and in the final differentiation of macrophage precursors to mature macrophages, as shown by follow-up of the antigenic profile by means of cytofluorograph analysis. The frequency of the IL-2-responding cells was 1/48 as determined by limiting dilution analysis, and no cell death was evidenced in soft agar cultures. An analysis of the IL-2-binding sites conducted on bone marrow-derived macrophage precursors revealed the presence of 4000 binding sites with intermediate affinity (Kd approximately 3 x 10(-9)). Bone marrow-derived macrophage precursors did not react, even after prolonged culture in IL-2-conditioned media, with mAb recognizing the binding site (AMT-13, 3C7) or a binding site-associate molecule (7D4) of a Mr 50,000 to 60,000 component of the IL-2R expressed by the IL-2-dependent T cell line CTLL-2. Cross-linking studies showed the presence of a single binding protein, with an apparent Mr of 70,000. Macrophage precursors also proved able to internalize human rIL-2 within the first 20 min of incubation at 37 degrees C. The implications of these findings are discussed.

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PubMed1989

Macrophage function in murine allogeneic bone marrow radiation chimeras in the early phase after transplantation.

We tested several of the functions of macrophages (M phi) in the early phase after allogeneic bone marrow transfer to get information about this important aspect of the nonspecific immune system in the T-cell-deficient recipient. On days 3-5 after transfer, the number of M phi was reduced in the spleen, liver, lungs, and peritoneal cavity (Pe). The phagocytosis of sheep red blood cells (SRBC) by these M phi was normal or even enhanced, as in the case of Pe-M phi. Already on days 8-12 after transfer, the number of M phi in spleen and liver exceeded that of controls, whereas the number was still reduced in lungs and Pe. We examined their ability to kill P815 tumor cells, to produce tumor necrosis factor-alpha (TNF alpha), to phagocytose SRBC, to produce reactive oxygen intermediates (ROI) in vitro and to kill Listeria monocytogenes in vivo. Most functions were normal and often even enhanced, depending on the organ origin, but the ability of Pe-M phi to produce ROI was reduced. Proliferative response to macrophage colony-stimulating factor (M-CSF) and killing of YAC-1 tumor cells revealed a high frequency of macrophage precursor cells in the spleen and liver and a high natural killer (NK) activity in the liver. Altogether, enhanced nonspecific immune function, especially preactivated M phi, may enable chimeras to survive attacks by opportunistic pathogens.

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PubMed1988

Extracellular killing of Leishmania promastigotes and amastigotes by macrophage precursors derived from bone marrow cultures.

Flagellates of the genus Leishmania are obligate intracellular parasites of vertebrates including man. The microorganisms reside and multiply inside the phagolysosomes of cells of the mononuclear phagocyte lineage. We here report on the spontaneous leishmanicidal activity exerted extracellularly by immature cells of the mononuclear phagocyte lineage. Highly purified, bone marrow-derived macrophage precursor cells displayed a strong spontaneous leishmanicidal activity already at very low effector/target rations (3:1, 6:1). This leishmanicidal activity was effective against both promastigotes and amastigotes as targets. The cytotoxic effect was evident within 4 h and maximal after 12 h of effector-target organism cocultivation, as determined by a radiolabel-release assay. An intimate cell-cell contact seemed necessary for the parasites to be killed.

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PubMed1988

Liver-associated macrophage precursor cells proliferate under impairment of regular hemopoiesis.

We reported previously that immature macrophage precursor cells can be isolated from spleen and liver of cyclophosphamide or pyran copolymer-pretreated mice. We now extended our investigations to livers of normal, untreated specific pathogen-free mice. Using the response to the macrophage growth factor colony-stimulating factor-1 (CSF-1) and the presence of the mouse macrophage-specific F4/80 antigen as criteria of definition, in the liver of normal mice we could demonstrate macrophage precursor (M phi P) cells by means of proliferation assays and flow cytometric analysis. The amount of M phi P present in the normal liver was significantly increased after administration of pyran copolymer. Also an enhanced proliferative response to CSF-1 as well as augmented natural killer activity and cytostasis of Candida albicans was noted in liver nonparenychymal cells (LNPC) after treatment of bone marrow (BM)-irradiated, splenectomized mice with pyran copolymer. Since the irradiated BM was actually proven to be silent by assessment of BM number and proliferative capacity and by scoring white blood cells, our findings suggest a response of endogenous liver M phi P under the applied conditions. Further evidence for the presence of endogenous liver hemopoietic cells was obtained from transplantation experiments in which LNPC brought about the survival of lethally irradiated mice. The data point towards a significance of the liver in disposing hemopoietic cells to the organism under impairment of regular hemopoiesis.

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PubMed1988

Macrophage precursors as natural killer cells against tumor cells and microorganisms.

Macrophage precursors cells have been isolated from spleen and liver of mice and have characterized using F4/80 antibody, their proliferative response to CSF-1 and their maturation to macrophages. These nonadherent and nonphagocytic cells exert strong killing of Yac-1 tumor cells and of various microorganisms. Transplantation of these macrophage precursors into lethally irradiated allogenic hosts restores natural killer (NK) activity within 14 days. Macrophage precursors show enhanced NK activity when activated with interleukin 2. FACS analysis of F 4/80 presorted macrophage precursors reveals about 30% of the cells coexpressing NK 1.1. and F 4/80. These data support the assumption that at least a part of the NK cell compartment is derived from the myeloid lineage.

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PubMed1986

A fast and objective assay for cell mediated intra- and extracellular killing of Leishmania promastigotes.

An in vitro radiometric assay is described for the detection of cytolytic activity against the obligate intracellular parasite Leishmania enriettii. The assay system can be equally well applied to non-cellular (humoral), cellular non-phagocytic, and cellular phagocytic effector situations. Leishmania promastigote organisms are DNA-labeled with [methyl-3H]thymidine [( 3H]dThd) with high efficiency. Spontaneous label release remains very low even in non-ideal culture conditions. We have modeled a leishmanicidal situation by co-cultivating L. enriettii with starch-elicited murine peritoneal macrophages for different time periods. At an effector-to-target ratio of 1:6 a highly significant [3H]dThd release can be observed after 4 h of co-cultivation, reaching 60% after 18 h. The principle advantages of this assay system are speed, high sensitivity and objectivity. This makes it suitable for mass screening of, e.g., immunomodulatory or parasiticidal agents and equally useful in both phagocytic and non-phagocytic situations.

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PubMed1986

Organ-associated macrophage precursor activity: isolation of candidacidal and tumoricidal effectors from the spleens of cyclophosphamide-treated mice.

We recently reported the modulating effects of a single injection of the anti-neoplastic drug cyclophosphamide (Cy; 150 mg/kg i.p.) on in vivo resistance against the experimental Candida albicans infection. Increased resistance to microbial challenge occurred 12 to 18 days after treatment. We now show that the increased resistance is paralleled by the appearance of potent nonadherent nonphagocytic effectors in the spleen (day 12) that are capable both of candidacidal activity and natural killer (NK) activity against YAC-1 cells. The cells mediating the two reactivities have a low buoyant density, a strong proliferating activity in response to the macrophage colony stimulating factor (CSF-1), and are unable to kill the NK-insensitive lines EL-4 and P815. A clear cut isolation of macrophage precursor cells from this Percoll low density fraction has been performed in an indirect rosette assay on the basis of their positivity for the surface markers recognized by the highly specific rat-anti-mouse macrophages, monoclonal antibodies M143 and F4/80. We obtained an extremely homogeneous population of cells in the early stage of macrophage differentiation that is responsible for all the candidacidal activity and for a major part of the NK activity observed in the spleen of Cy-treated mice, and which is extremely sensitive to CSF-1 induction.

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PubMed1986

Liver-associated macrophage precursors as natural cytotoxic effectors against Candida albicans and Yac-1 cells.

Liver nonparenchymal cells of maleic anhydride divinyl ether or cyclophosphamide-treated mice were assayed for cytotoxic activity against the yeast form of Candida albicans. A strong increase in this activity was observed after both in vivo treatments, as compared to untreated control mice. The effector cell was enriched by nylon wool passage and separation of nonadherent liver nonparenchymal cells on a discontinuous Percoll gradient. By means of direct and indirect rosetting techniques, based on the presence of Fc receptors and the F4/80 and M143 macrophage surface markers, we could separate a nearly homogeneous effector cell population. It displayed, besides the candidacidal activity, Fc receptors and the M143 and F4/80 antigens, also strong natural cytotoxicity against Yac-1 lymphoma cells. When cultured in medium containing colony-stimulating factor-1, this effector population reacted with a strong proliferative response as measured through incorporation of tritiated thymidine. The data presented show that nonadherent, nonphagocytic macrophage precursors, which we characterized previously from in vitro bone marrow cultures, occur in vivo as organ-associated effector cells in the liver after elicitation with maleic anhydride divinyl ether or cyclophosphamide. These macrophage precursors have prior to their maturation the ability to serve as a microbicidal and tumoricidal natural killer cell.

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PubMed1986

Functional heterogeneity of murine macrophage precursor cells from spleen and bone marrow.

We previously reported that highly purified bone marrow-derived macrophage precursors can exert strong spontaneous cytotoxicity against YAC-1 tumor cells, Candida albicans, and protozoa of the genus Leishmania. In the present paper, evidence is shown that macrophage precursors in normal untreated mice are not confined to the bone marrow compartment but can also be found in the spleen. These organ-associated cells, which have the same buoyant density as large granular lymphocytes, have been positively sorted by means of an indirect rosetting technique employing the macrophage-specific monoclonal antibodies F4/80 and M143. The rosetting fractions represented an extremely homogeneous population of macrophage precursors characterized by high candidacidal and natural killer activity and by a strong proliferative response to the macrophage-specific colony-stimulating factor CSF-1. Spleen- and bone marrow-derived macrophage precursors differed in their target selectivity. In addition, the mature macrophages derived in vitro from these two precursor populations displayed striking differences in their candidacidal activity. The implications of these findings in relationship to heterogeneity in the macrophage differentiation line are discussed.

Animals↗
PubMed1986

Heterogeneous activity of immature and mature cells of the murine monocyte-macrophage lineage derived from different anatomical districts against yeast-phase Candida albicans.

Mature mononuclear phagocytes have been receiving much attention as effectors of spontaneous candidacidal activity, although with controversial results due to differences in the effector populations and the methods used in different laboratories. We here systematically compare the fungistatic activity of immature and mature cells of the murine macrophage series. The results show that nonadherent, nonphagocytic precursor cells (isolated either [90% purity] from bone marrow liquid cultures or from the organs of mice in which inflammatory conditions had been elicited in vivo) exerted a strong extracellular candidastatic activity. In contrast, mature macrophages, either obtained from different anatomical areas (spleen, liver, lung, peritoneal cavity) or matured in vitro from the precursor populations, displayed striking heterogeneity in their ability to inhibit the growth of Candida albicans, depending on the anatomical site they were derived from. Lymphokine activation did not alter the fungistatic pattern of the untreated cells. The different macrophage populations behaved very differently also in the production of reactive oxygen intermediates (ROI) in response to phagocytosis of C. albicans. The amounts of ROI generated, however, showed no correlation with candidastatic ability. Low levels of candidastatic activity exerted by resident peritoneal macrophages (good ROI producers) were inhibited by catalase, whereas high levels of growth inhibition by Kupffer cells (poor ROI producers) after 8 h of assay were hardly influenced by the enzyme. Our data suggest the existence of two different effector mechanisms in macrophage-mediated C. albicans growth inhibition, a rather inefficient ROI-dependent one, and a second, very efficient oxygen-independent mechanism. The implications of these findings are discussed.

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PubMed1985

Killing of yeast, germ-tube and mycelial forms of Candida albicans by murine effectors as measured by a radiolabel release microassay.

Candida albicans undergoes yeast to mycelial conversion under both in vivo and in vitro conditions but the relative pathogenicity of the two forms of growth is still unknown. By adapting a recently developed 51Cr radiolabel release assay, we have quantified the killing ability of different murine effector cell populations for the hyphal form of C. albicans. Up to 50% of specific 51Cr release from the mycelial form could be detected after incubation for only 1 h, with no requirement for opsonization, provided that appropriate effector: target cell ratios were used. The specific 51Cr release correlated well with viability, as assessed by dye exclusion tests, and with pathogenicity potential in cyclophosphamide-immunodepressed mice. Comparison of the activity of different murine effectors against yeast and hyphal forms showed that hyphal forms were killed by murine effectors to a similar, if not greater, extent than yeast forms. In particular, thioglycollate-induced murine polymorphonuclear neutrophils were able to kill hyphal cells extracellularly and without an opsonic requirement.

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