Pattern of human monocyte subpopulations in health and disease.

Monocytes are important cells of the innate system. They are a heterogeneous type of cells consisting of phenotypically and functionally distinct subpopulations, which play a specific role in the control, development and escalation of the immunological processes. Based on the expression of superficial CD14 and CD16 in flow cytometry, they can be divided into three subsets: classical, intermediate and non-classical. Variation in the levels of human monocyte subsets in the blood can be observed in patients in numerous pathological states, such as infections, cardiovascular and inflammatory diseases, cancer and autoimmune diseases. The aim of this review is to summarize current knowledge of human monocyte subsets and their significance in homeostasis and in pathological conditions.

[Undifferentiated carcinoma of the jejunum producing granulocyte colony-stimulating factor].

An 80-year-old man presented with abdominal fullness and vomiting. Laboratory data revealed severe anemia, an inflammatory response, and elevated white blood cell counts. Abdominal computed tomography indicated ileus caused by a jejunal tumor measuring 8cm in diameter. Although small-bowel endoscopy enabled visualization of the tumor, adequate biopsy specimens could not be obtained for accurate diagnosis. The patient's condition rapidly deteriorated, because of which surgical treatment could not be initiated. The patient died approximately 3 weeks after admission. High serum granulocyte colony-stimulating factor (G-CSF) levels were detected at autopsy. Immunohistochemical staining of the autopsy specimen indicated positive G-CSF levels in the jejunal tumor. On the basis of these findings, a final diagnosis of undifferentiated carcinoma of the jejunum producing G-CSF was made.

Maternal immune activation by poly I:C induces expression of cytokines IL-1ß and IL-13, chemokine MCP-1 and colony stimulating factor VEGF in fetal mouse brain.

BACKGROUND: Maternal viral infection during pregnancy is associated with an increase in the incidence of psychiatric disorders with presumed neurodevelopmental origin, including autism spectrum disorders and schizophrenia. The enhanced risk for developing mental illness appears to be caused by deleterious effects of innate immune response-associated factors on the development of the central nervous system, which predispose the offspring to pathological behaviors in adolescence and adulthood. To identify the immune response-associated soluble factors that may affect central nervous system development, we examined the effect of innate immune response activation by polyriboinosinic-polyribocytidylic acid (poly(I:C)), a synthetic analogue of viral double-stranded RNA, on the expression levels of pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors in fetal and postnatal mouse brain 6 h and 24 h after treatment. METHODS: C57BL/6J pregnant mice (gestational day 16) or newborn mice (postnatal day 4) received a single intraperitoneal injection of the synthetic analogue of viral double-stranded RNA poly(I:C) (20 mg/kg). Thirty-two immune response-associated soluble factors, including pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors, were assayed 6 h and 24 h after poly(I:C) injection using multiplexed bead-based immunoassay (Milliplex Map) and processed in a Luminex 100 IS instrument. RESULTS: Maternal exposure to poly(I:C) at gestational day 16 induced a significant increase in cytokines interleukin (IL)-1ß, IL-7 and IL-13; chemokines monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein (MIP)-1α, interferon gamma-induced protein (IP)-10 and monokine induced by IFN-gamma (MIG); and in the colony stimulating factor vascular endothelial growth factor (VEGF) in the fetal brain. IL-1ß showed the highest concentration levels in fetal brains and was the only cytokine significantly up-regulated 24 h after maternal poly(I:C) injection, suggesting that IL-1ß may have a deleterious impact on central nervous system development. In contrast, poly(I:C) treatment of postnatal day 4 pups induced a pronounced rise in chemokines and colony stimulating factors in their brains instead of the pro-inflammatory cytokine IL-1ß. CONCLUSIONS: This study identified a significant increase in the concentration levels of the cytokines IL-1ß and IL-13, the chemokine MCP-1 and the colony stimulating factor VEGF in the developing central nervous system during activation of an innate immune response, suggesting that these factors are mediators of the noxious effects of maternal immune activation on central nervous system development, with potential long-lasting effects on animal behavior.

IL-33 activates unprimed murine basophils directly in vitro and induces their in vivo expansion indirectly by promoting hematopoietic growth factor production.

IL-33, a new member of the IL-1 family, has been described as an important inducer of Th2 cytokines and mediator of inflammatory responses. In this study, we demonstrate that murine basophils sorted directly from the bone marrow, without prior exposure to IL-3 or Fc(epsilon)R cross-linking, respond to IL-33 alone by producing substantial amounts of histamine, IL-4, and IL-6. These cells express ST2 constitutively and generate a cytokine profile that differs from their IL-3-induced counterpart by a preferential production of IL-6. In vivo, IL-33 promotes basophil expansion in the bone marrow (BM) through an indirect mechanism of action depending on signaling through the beta(c) chain shared by receptors for IL-3, GM-CSF, and IL-5. IL-3 can still signal through its specific beta(IL-3) chain in these mutant mice, which implies that it is not the unique growth-promoting mediator in this setup, but requires IL-5 and/or GMCSF. Our results support a major role of the latter growth factor, which is readily generated by total BM cells as well as sorted basophils in response to IL-33 along with low amounts of IL-3. Furthermore, GM-CSF amplifies IL-3-induced differentiation of basophils from BM cells, whereas IL-5 that is also generated in vivo, affects neither their functions nor their growth in vitro or in vivo. In conclusion, our data provide the first evidence that IL-33 not only activates unprimed basophils directly, but also promotes their expansion in vivo through induction of GM-CSF and IL-3.

Lysozyme synthesis by established human and murine histiocytic lymphoma cell lines.

A human cell line established in culture from a histiocytic lymphoma patient synthesizes and secretes the monocyte-granulocyte specific enzyme lysozyme. 18 other human cell lines with characteristics of T-lymphocyte, B-lymphocyte, Burkitt's lymphoma, non-Burkitt's lymphoma, myeloma, and bone marrow epithelial cells were not associated with lysozyme. Among murine cell lines, lysozyme was produced by (a) three histiocytic lymphoma or macrophage lines, which mediate antibody-dependent phagocytosis and cytolysis; (b) myelomonocytic leukemia line which also secretes myeloid colony-stimulating factor; and (c) a spontaneous lymphoma and an Abelson leukemia virus-induced lymphoma. Lysozyme-negative lines include another Abelson lymphoma, myelomas, T lymphomas, and mastocytoma.

Precursor frequency analysis of lymphokine-secreting alloreactive T lymphocytes. Dissociation of subsets producing interleukin 2, macrophage-activating factor, and granulocyte-macrophage colony-stimulating factor on the basis of Lyt-2 phenotype.

The frequencies of precursors of C57BL/6 T lymphocytes that respond to DBA/2 alloantigens by secreting the lymphokines interleukin 2 (IL-2), macrophage-activating factor (MAF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been directly compared with cytolytic T lymphocyte precursor (CTL-P) frequencies in limiting dilution microcultures established from spleen cells positively or negatively selected on the basis of Lyt-2 phenotype. A clear dichotomy was observed between CTL-P, which were contained in the Lyt-2+ fraction, and precursors of IL-2-secreting cells, which were detected almost exclusively in the Lyt-2- population. In contrast, precursors of cells secreting MAF and GM-CSF were found in both populations: almost all responding cells from the Lyt-2- fraction produced both these factors, whereas the precursor frequency of MAF-secreting and GM-CSF-secreting cells was three- to fourfold lower in the Lyt-2+ population. These frequency data were consistent with quantitative differences observed in the average production of these lymphokines by Lyt-2+ and Lyt-2- populations.

Enhancement of human blood eosinophil cytotoxicity by semi-purified eosinophil colony-stimulating factor(s).

Purified human blood eosinophils, when incubated in human placental conditioned medium (a source of colony-stimulating factors) [CSF]) demonstrate an enhanced ability to damage antibody- or complement-coated schistosomula. This enhancement represents a 4- to 10-fold increase of eosinophil schistosomicidal ability and a 10-fold lowering of the threshold for antibody or complement required in the killing reaction. The activity that enhances eosinophil cytotoxicity and the eosinophil colony-stimulating activity in the placental conditioned medium are eluted in the same fraction (CSF-alpha) after chromatography on Sephadex G-100 and phenyl-Sepharose columns, suggesting that these two activities might be associated with the same molecule. CSF-alpha enhances the adherence step of the killing reaction: antibody-coated larvae were frequently found covered by several layers of eosinophils in tubes containing CSF-alpha. Such a degree of adherence was rarely seen in control tubes lacking CSF-alpha. This enhancement of the eosinophil adherence is detectable 45-60 min after addition of CSF-alpha to the culture. It is not affected by washing the cells after a short time of preincubation with CSF-alpha, and it occurs in the absence of protein synthesis, whereas colony-stimulating activity requires continuous protein synthesis and ceases when CSF is removed from the culture. Finally, CSF-alpha enhances the temperature-dependent reaction that insures the irreversibility of eosinophil attachment to schistosomula. These observations suggest that eosinopoietic factors could be responsible for some of the modified properties of blood eosinophils in eosinophilic individuals.

Regulation of parasite-induced eosinophilia: selectively increased interleukin 5 production in helminth-infected patients.

Production of the eosinophilogenic cytokines interleukin 3 (IL-3), granulocyte/macrophage colony-stimulating factor (GM-CSF), and IL-5 by mitogen-stimulated peripheral blood mononuclear cells was compared between 11 noneosinophilic individuals and seven patients with helminth-induced eosinophilia. Both the kinetics and quantities of IL-3 and GM-CSF were similar in the two groups. In contrast, IL-5 production at both the protein and the mRNA level was markedly greater in the eosinophilic patients, an observation suggesting that IL-5 may be particularly important in mediating the selective eosinophilia seen in filarial and other helminth infections.

A distinct wave of human T cell receptor gamma/delta lymphocytes in the early fetal thymus: evidence for controlled gene rearrangement and cytokine production.

The rearrangement and expression of human T cell receptor (TCR)-gamma and -delta gene segments in clonal and polyclonal populations of early fetal and postnatal human TCR-gamma/delta thymocytes were examined. The data suggest that the TCR-gamma and -delta loci rearrange in an ordered and coordinated fashion. Initial rearrangements at the TCR-delta locus join V delta 2 to D delta 3, and initial rearrangements at the TCR-gamma locus join downstream V gamma gene segments (V gamma 1.8 and V gamma 2) to upstream J gamma gene segments associated with C gamma 1. These rearrangements are characterized by minimal junctional diversity. At later times there is a switch at the TCR-delta locus such that V delta 1 is joined to upstream D delta gene segments, and a switch at the TCR-gamma locus such that upstream V gamma gene segments are joined to downstream J gamma gene segments associated with C gamma 2. These rearrangements are characterized by extensive junctional diversity. Programmed rearrangement explains in part the origin of discrete subpopulations of peripheral blood TCR-gamma/delta lymphocytes that have been defined in previous studies. In addition, cytokine production by early fetal and postnatal TCR-gamma/delta thymocyte clones was examined. Fetal thymocyte clones produced significant levels of IL-4 and IL-5 following stimulation, whereas postnatal thymocyte clones did not produce these cytokines. Thus, these cell populations may represent functionally distinct subsets as well.

Abrogation of the requirement for feeder cell interaction and T cell receptor stimulation of lymphocytes infected with retroviral vectors.

Infection of sensitive adult mice with myeloproliferative sarcoma virus (MPSV) results in a myeloproliferative syndrome. Two components of the viral genome are required to induce this unique pathology: the mos oncogene and sequences within the U3 region of the long terminal repeat (LTR). In studies designed to identify the target cell of MPSV and thus better understand the mechanism by which a myeloproliferative syndrome is induced, we have infected a series of T cell lines with MPSV-based vectors. The results presented here show that infection with neoR MPSV abrogates the requirement for an antigen-specific or feeder cell-dependent stimulation, without altering the requirement for interleukin 2. Significantly, this response is not dependent on the mos oncogene, but requires sequences within the U3 region of the MPSV LTR. No alteration in the constitutive or induced levels of lymphokines released by these cells was observed. These results suggest a model in which T cells acquire a proliferative advantage by uncoupling the proliferative response from the lymphokine synthesis that is induced by activation of the T cell receptor. These cells are thus poised for antigen stimulation and secretion of cytokines that stimulate myelopoiesis.

Production of hematopoietic colony-stimulating factors by human natural killer cells.

We have analyzed the ability of highly purified preparations of human NK cells to produce CSF. NK cells, purified by negative selection from 10-d cultures of PBMC incubated with irradiated B-lymphoblastoid cell lines, were stimulated with rIL-2, FcR(CD16) ligands (particulate immune complexes or anti-CD16 antibodies bound to Sepharose), a combination of CD16 ligands and rIL-2, or the phorbol diester phorbol dibutyrate (PDBu) together with the Ca2+ ionophore A23187. Both rIL-2 and CD16 ligands induce accumulation of GM-CSF mRNA in NK cells and the combined effect of the two stimuli is synergistic. Maximal accumulation of GM-CSF mRNA is observed after PDBu/A23187 stimulation. The participation of contaminant T cells in the observed expression of the GM-CSF gene is excluded because CD16 ligands do not stimulate T cells and CD3 ligands, powerful stimulators of T cells, are inactive on NK cells. Accumulation of CSF-1 mRNA is observed only in NK cells stimulated with both CD16 ligands and rIL-2, whereas accumulation of IL-3 mRNA is observed only in NK cells stimulated with PDBu/A23187. Transcripts of the G-CSF, IL-1 alpha, and IL-1 beta genes were never detected in NK cells in these experiments. The kinetics of accumulation of GM-CSF and CSF-1 mRNA in NK cells stimulated with CD16 ligands and rIL-2 peaked at 2-4 h and was slower than that of TNF and IFN-gamma mRNA, which peak at 1 h. GM-CSF was precipitated from the supernatant fluids of NK cells stimulated with PDBu/A23187 and its biological activity was demonstrated by the ability of the supernatants to sustain proliferation of the TALL-101 cell line or CML blasts. Biological activity of IL-3 and CSF-1 was demonstrable in supernatant fluids of NK cells stimulated with PDBu/A23187 and CD16 ligands/rIL-2, respectively.

Immunostimulators induce granulocyte/macrophage colony-stimulating activity and block proliferation in a monocyte tumor cell line.

Monocyte tumor cell line PU5-1.8 does not normally produce colony-stimulating activity (CSA) required by granulocyte and macrophage progenitors to proliferate and mature in agar. However, CSA is induced in the culture line by as little as 10 ng/ml endotoxic lipopolysaccharide (LPS), with maximum CSA production and release to the medium between 2 and 3 days of incubation. Derived lipid A, but not alkali-treated LPS, is also active. Induction requires RNA and protein synthesis, but is not blocked by mitomycin C or Colcemid. Other inducers of CSA include Mycobacterium Bacillus Calmette-Guérin, tuberculin protein preparation purified protein derivative, zymosan, and phorbol myristate. All inducing agents are specific inhibitors of the monocyte tumor cell proliferation in vitro. Latex beads, another macrophage-activating agent, are rapidly phagocytosed by PU5-1.8 cells, but neither inhibit growth nor induce CSA.

Synthesis of granulocyte colony-stimulating factor and its requirement for terminal divisions in chronic myelogenous leukemia.

In this paper we demonstrate that maturing neoplastic cells from patients with chronic myelogenous leukemia (CML) constitutively produce G-CSF and are also receptive for this molecule. G-CSF functions as an autocrine growth factor in stable phase CML, and thus is responsible for divisions of maturing leukemic cells leading to an expansion of the compartment of mature cells. This observation is well in line with in vivo features of CML in stable phase, i.e., the hyperplasia of the mature granulocyte compartment. In acute blastic phase of CML expression of the G-CSF gene seems to be less common and not related to autonomous blast growth.

Two types of mouse helper T cell clone. III. Further differences in lymphokine synthesis between Th1 and Th2 clones revealed by RNA hybridization, functionally monospecific bioassays, and monoclonal antibodies.

Lymphokine synthesis patterns of a panel of 19 T cell clones have been evaluated, using mRNA hybridization methods to examine 11 different mRNAs induced by Con A. The two types of CD4+ Th cell clone described previously were clearly distinguished by this procedure, and the differences between the two types have now been extended to six induced products. With minor exceptions, only Th1 clones synthesized mRNA for IL-2, IFN-gamma, and lymphotoxin, and only Th2 clones synthesized mRNA for IL-4, IL-5, and another induced gene, P600. Four more induced products were expressed preferentially but not uniquely by one or another type of clone: mRNAs for GM-CSF, TNF, and another induced, secreted product (TY5) were produced in larger amounts by Th1 clones, whereas preproenkephalin was preferentially expressed by Th2 clones. IL-3 was produced in similar amounts by both types of clone. mAbs were used to establish three bioassays that were functionally monospecific for IL-2, IL-3, and IL-4, and a new anti-IFN gamma mAb, XMG1.2, was used to establish an ELISA for IFN-gamma. These four assays were used to show that secreted protein and mRNA levels correlated well for all cell lines. The implications of these findings for normal T cells are discussed.

HPV11E7 inhibits IMQ-induced chemokine and colony-stimulating factor production in keratinocytes.

Imiquimod (IMQ) is approved as a first-line treatment for genital warts caused by human papillomavirus (HPV) infection. However, the recurrence rate is very high. HPV E7 protein plays a critical role in HPV immune escape. However, the role of HPV11 E7 protein in genital warts recurrence during IMQ treatment is not clear. Here, we found that the expression profile of NHEK cells was obviously changed after IMQ treatment, and a large number of genes encoding cytokines and genes involved in cytokine-mediated signaling pathways and cellular metabolic signaling pathways were up- or downregulated. HPV11E7 overexpression inhibited the IMQ-induced production of of multiple chemokines and colony-stimulating factors in NHEK cells. Furthermore, we found that HPV11E7 could impair the activation of mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, our results suggested that HPV11 E7 diminishes the production of chemokines, colony-stimulating factors and other cytokines via inhibition of the MAPK signaling pathway, which suppresses the therapeutic effect of IMQ and promotes the recurrence of diseases, such as condyloma acuminatum.

Human GM-CSF: molecular cloning of the complementary DNA and purification of the natural and recombinant proteins.

Clones of complementary DNA encoding the human lymphokine known as granulocyte-macrophage colony-stimulating factor (GM-CSF) were isolated by means of a mammalian cell (monkey COS cell) expression screening system. One of these clones was used to produce recombinant GM-CSF in mammalian cells. The recombinant hematopoietin was similar to the natural product that was purified to apparent homogeneity from medium conditioned by a human T-cell line. The human T-cell GM-CSF was found to be 60 percent homologous with the GM-CSF recently cloned from murine lung messenger RNA.

Induction of macrophage tumoricidal activity by granulocyte-macrophage colony-stimulating factor.

Monocytes are a subpopulation of peripheral blood leukocytes, which when appropriately activated by the regulatory hormones of the immune system, are capable of becoming macrophages--potent effector cells for immune response to tumors and parasites. A complementary DNA for the T lymphocyte-derived lymphokine, granulocyte-macrophage colony-stimulating factor (GM-CSF), has been cloned, and recombinant GM-CSF protein has been expressed in yeast and purified to homogeneity. This purified human recombinant GM-CSF stimulated peripheral blood monocytes in vitro to become cytotoxic for the malignant melanoma cell line A375. Another T cell-derived lymphokine, gamma-interferon (IFN-gamma), also stimulated peripheral blood monocytes to become tumoricidal against this malignant cell line. When IFN-gamma activates monocytes to become tumoricidal, additional stimulation by exogenously added lipopolysaccharide is required. No such exogenous signals were required for the activation of monocytes by GM-CSF.

Human recombinant granulocyte-macrophage colony-stimulating factor: a multilineage hematopoietin.

Human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was tested for its ability to induce colony formation in human bone marrow that had been enriched for progenitor cells. In addition to its expected granulocyte-monocyte colony-stimulating activity, the recombinant GM-CSF had burst-promoting activity for erythroid burst-forming units and also stimulated colonies derived from multipotent (mixed) progenitors. In contrast, recombinant erythroid-potentiating activity did not stimulate erythroid progenitors. The experiments prove that human GM-CSF has multilineage colony-stimulating activity.

Interleukin 1 stimulates fibroblasts to produce granulocyte-macrophage colony-stimulating activity and prostaglandin E2.

Granulocyte-macrophage colony-stimulating activity (GM-CSA) can be produced by a variety of normal cell types including mononuclear phagocytes, activated T lymphocytes, endothelial cells, and fibroblasts. Recent evidence shows that a major role of the monocyte-macrophage is the recruitment of environmental cells, i.e., fibroblasts, to produce GM-CSA. In this study we have identified interleukin 1 (IL-1) as a monokine that stimulates fibroblasts to produce and release GM-CSA and prostaglandin E2 (PGE2). Both purified human monocyte-derived IL-1 and human recombinant IL-1 (10(-10) M) can be substituted for monocyte-conditioned medium in stimulating fibroblast GM-CSA and PGE2 production. Both forms of IL-1 stimulate fibroblasts to produce GM-CSA and PGE2 in a dose-dependent fashion. The fibroblast-stimulating activity found in monocyte-conditioned medium was completely blocked by anti-IL-1. We conclude that monocytes produce IL-1, and that monocyte-derived IL-1 induces fibroblasts to produce GM-CSA and PGE2.

Lactoferrin acts on Ia-like antigen-positive subpopulations of human monocytes to inhibit production of colony stimulatory activity in vitro.

The relationship between Ia-like antigens (Ia-antigens) on human monocytes and the ability of lactoferrin (LF) to inhibit the production of colony stimulatory activity (CSA) for granulocyte and macrophage colony formation was investigated. Complement-dependent cytotoxicity of human monocytes by antiserum to Ia-antigen-reduced CSA production by 50%. LF decreased CSA production by monocytes but had no influence on monocytes insensitive to anti-Ia and complement. Anti-Ia in the absence of complement had no effect on production of CSA but blocked the inhibitory action of LF. This suggsts that LF inhibits production of CSA from an Ia-antigen-positive subpopulation of human blood monocytes. This may be of relevance to the regulation of myelopoiesis.