rhG-CSF does not affect the phenotype of adult donor peripheral blood NK cells

Considerable evidence in preclinical models as well as in human transplantation now suggests that donor-derived natural killer (NK) cells can contribute to alloimmune recognition of recipient residual tumour cells. This makes the NK cell population an attractive target for in vitro or in vivo manipulations, in order to improve the antitumour effect of allogeneic transplantation. However, conditions in which allogeneic donor cells are collected vary; several reports have emphasised the different phenotypic and functional properties of T cells derived from marrow, cord blood or mobilised peripheral blood grafts; others have demonstrated different clinical outcomes following blood or marrow transplantation after myeloablative conditioning regimens. NK cells have been examined in this setting; the availability of new tools to study the expression of a variety of surface antigens that are involved in the control of NK cell activity offered us an opportunity to extensively characterise the phenotypic properties of NK cells from donors, before and after administration of pharmacological doses of rhG-CSF used for haematopoietic progenitor mobilisation. Our study suggests that rhG-CSF does not reproducibly alter blood NK cell phenotype in normal individuals, and thus that donor-derived cells are fully equipped to exert their potential antitumour effect.

Decreased transcription of the human FCGR2B gene mediated by the -343 G/C promoter polymorphism and association with systemic lupus erythematosus

The role for inhibitory Fc gamma receptors class IIb (FcgammaRIIb) in the onset, progression and severity of several animal models of autoimmune diseases is well established. By contrast, the pathogenic potential of FcgammaRIIb in human autoimmune diseases remains largely unknown. Here we report the identification of a polymorphism in the human FCGR2B promoter (dbSNP no. rs3219018) that is associated in homozygosity with systemic lupus erythematosus (SLE) phenotype in European-Americans (OR=11.1, P=0.003). Experimental evidence correlates the polymorphism (a G-C substitution at position -343 relative to the start of transcription) with altered FcgammaRIIb expression and function. The G-C substitution correlated with decreased transcription of the FCGR2B promoter, and resulted in decreased binding of the AP1 transcription complex to the mutant promoter sequence. The surface expression of FcgammaRIIb receptors was significantly reduced in activated B cells from (-343 C/C) SLE patients. These findings suggest that genetic defects may lead to deregulated expression of the FCGR2B gene in -343 C/C homozygous subjects, and may play a role in the pathogenesis of human SLE.

Development of proteoglycan-induced arthritis is critically dependent on Fcγ receptor type III expression

OBJECTIVE

To study the necessity for activating Fcgamma receptor types I and III (FcgammaRI and FcgammaRIII) in proteoglycan-induced arthritis (PGIA), a murine model of rheumatoid arthritis, and to determine whether usage of FcgammaRI or FcgammaRIII correlates with the Th1 phenotype or the autoantibody isotype in PGIA.

METHODS

PGIA was induced by immunizing FcgammaRI(-/-), FcgammaRIII(-/-), and wild-type (WT) littermate mice with human PG. The development and severity of arthritis were monitored over time. PG-specific T cell interleukin-2 (IL-2) production and B cell antibody responses were assessed. FcgammaRIII blocking antibodies were used to inhibit arthritis in an adoptive transfer system. Inflammation in the hind paws was evaluated by assessing cytokine and chemokine messenger RNA (mRNA) transcripts by real-time polymerase chain reaction.

RESULTS

FcgammaRI(-/-) mice developed arthritis with similar kinetics and severity as WT littermate controls, whereas FcgammaRIII(-/-) mice failed to develop the disease. Both FcgammaRI(-/-) and FcgammaRIII(-/-) mice produced similar amounts of PG-specific antibody and IL-2 as littermate controls. Transfer of arthritis was successfully blocked in mice treated with a blocking antibody against FcgammaRIII. FcgammaRIII(-/-) mice displayed a significant decrease in cytokine and chemokine mRNA transcripts obtained from the hind paws of immunized mice, whereas FcgammaRI(-/-) mice demonstrated a similar increase in cytokine and chemokine transcripts as controls.

CONCLUSION

These results demonstrate that FcgammaRIII expression is critical to the development of PGIA, and usage of FcgammaRIII correlates with the IgG1 isotype of the PG-specific antibody response. FcgammaRIII expression appears to be important in the effector phase of arthritis, possibly by activating cytokine- and chemokine-secreting cells in the joint.

Signal-Specific Activation and Regulation of Human Neutrophil Fcγ Receptors

FcgammaRs with the ITIM domain have been shown to regulate the inflammatory signal delivered by the ITAM-containing FcgammaRs. In this study, we demonstrate that the function of human neutrophil FcgammaR type IIA (CD32A) is regulated in a distinct manner by different cell activation signals at the ligand-binding stage. Activation of neutrophils with fMLP up-regulated the ligand-binding function of CD32A, whereas PMA-mediated activation completely abolished ligand binding without altering CD32A expression. Furthermore, PMA treatment also abolished CD16B-dependent ligand binding irrespective of the level of expression. The effect of PMA was cell type specific, because the ligand-binding function of CD32A expressed on cultured cells such as K562 and CHO-CD32A transfectants was not affected by PMA. Interestingly, phorbol 12,13-dibutyrate, another phorbol ester, and IL-8 up-regulated CD32A-dependent ligand-binding function. These results demonstrate that regulation of CD32A-dependent ligand binding in human neutrophils is not only cell type specific but also activation signal specific. Moreover, these results suggest the possibility that signals delivered to neutrophils by various inflammatory stimuli can exert opposing effects on the function of human FcgammaRs, representing a novel inside-out regulatory mechanism of FcgammaR ligand binding.

Immature Neutrophils Mediate Tumor Cell Killing via IgA but Not IgG Fc Receptors

Antitumor Abs are promising therapeutics for cancer. Currently, most Ab-based therapies focus on IgG Ab, which interact with IgG FcR (FcgammaR) on effector cells. In this study, we examined human and mouse neutrophil-mediated tumor cell lysis via targeting the IgA FcR, FcalphaRI (CD89), in more detail. FcalphaRI was the most effective FcR in triggering tumor cell killing, and initiated enhanced migration of neutrophils into tumor colonies. Importantly, immature neutrophils that are mobilized from the bone marrow upon G-CSF treatment efficiently triggered tumor cell lysis via FcalphaRI, but proved incapable of initiating tumor cell killing via FcgammaR. This may provide a rationale for the disappointing results observed in some earlier clinical trials in which patients were treated with G-CSF and antitumor Ab-targeting FcgammaR.

The low affinity Fc receptor for IgG functions as an effective cytolytic receptor for self-specific CD8 T cells

We have recently described a population of self-Ag-specific murine CD8(+) T cells with a memory phenotype that use receptors of both the adaptive and innate immune systems in the detection of transformed and infected cells. In this study we show that upon activation with IL-2 with or without Ag, between 10 and 20% of the activated self-specific CD8(+) T cells express the low affinity FcR for IgG. By contrast, all IL-2-activated NK cells express high levels of this FcR. The FcR comprises the FcgammaRIIIalpha and FcRgamma subunits. However, the FcRgamma subunit also associates with the CD3 complex, and this association probably contributes to the low expression of FcR in activated cells. Although the FcR is expressed at a low level on activated self-specific CD8(+) T cells, it functions very efficiently as a cytolytic receptor in ADCC. FcR-dependent killing occurred in the absence of TCR stimulation, but could be augmented by concurrent stimulation of the TCR. In addition to mediating ADCC, engagement of the FcR on self-specific CD8(+) T cells results in the production of both IFN-gamma and TNF-alpha. This is the first report of an activating FcR on self-specific murine CD8(+)alphabeta TCR(+) T cells and establishes the importance of innate immune system receptors in the function of these self-specific CD8(+) T cells.

Fc gamma R expression on NK cells influences disease severity in rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with autoantibodies, the best known of which is rheumatoid factor (RF). RF/IgG complexes interact with FcgammaR on the surface of neutrophils, NK cells and monocyte/macrophages. We have analyzed the expression pattern and allelic polymorphisms of three FcgammaR genes (FcgammaRIIA, FcgammaRIIC and FcgammaRIIIA) in a large sample of RA patients and normal donors. We have found that the level of FcgammaR (CD16 and CD32) expression on NK cells is lower in RA patients than in normal individuals. Genotypic analysis demonstrated that the CD32 isoform expressed by the majority of RA patients was not the activating FcgammaRIIc1 isoform, commonly seen in normal individuals, but rather the inhibitory FcgammaRIIb isoform. The combination of the FcgammaRIIIA-176F allele with a lack of CD32 expression in NK cells appeared to be characteristic of RA subjects with aggressive disease. Since FcgammaRII and FcgammaRIIIA are predominantly expressed by NK cells, these data further suggest that FcgammaR-mediated activation of NK cells could be a disease-determining factor in RA patients.

HER2-specific cytotoxic activity of lymphokine-activated killer cells in the presence of trastuzumab

We investigated whether trastuzumab, a humanized anti-HER2 monoclonal antibody, could induce HER2-specific cytotoxic activity on lymphokine-activated killer (LAK) cells. Trastuzumab alone was not toxic to the HER2-positive breast cancer cell lines MDA-MB453 and ZR75-1, nor to the HER2-negative breast cancer cell lines MDA-MB468 and MCF-7. LAK cells, which were activated with 1000 U/ml IL-2 for 4 days (4-day LAK), showed cytotoxic activity against the MDA-MB453, ZR75-1 and MCF-7 cells, but not against MDA-MB468 cells. LAK cell cytotoxic activity against the HER2-positive breast cancer cell lines MDA-MB453 and ZR75-1 was significantly augmented in the presence of 10 nM trastuzumab, but that against the HER2-negative breast cancer cell lines MDA-MB468 and MCF-7 was not. The cytotoxic activity of LAK cells plus trastuzumab against the MDA-MB453 cells was significantly inhibited by the addition of cold MDA-MB453 cells or cold ZR75-1 cells, but not by addition of cold MDA-MB468 cells. Twenty-nine percent of the 4-day LAK cells were CD16+, and the cytotoxicity of LAK cells plus trastuzumab was abrogated with the anti-CD16 antibody treatment of the LAK cells in the cytotoxicity assay. Only 7% of the 10-day LAK cells were CD16+, and the 10-day LAK cells failed to exhibit cytotoxicity even with trastuzumab. These results suggest that HER2-specific cytotoxic activity, which is mediated by an antibody-dependent cellular cytotoxicity (ADCC) mechanism, can be induced on LAK cells by the addition of trastuzumab.

Functional humanization of an anti-CD30 Fab fragment for the immunotherapy of Hodgkin's lymphoma using an in vitro evolution approach

CD30, the so-called Reed-Sternberg antigen, constitutes a promising cell-specific target for the treatment of Hodgkin's lymphoma. Starting from the previously characterized cognate HRS3 mouse monoclonal antibody, the bacterially produced functional Fab fragment was humanized by grafting the CDRs from the mouse antibody framework on to human immunoglobulin consensus sequences. This procedure led to a 10-fold decreased antigen affinity, which surprisingly was found to be mainly due to the VH domain. To improve the antigen-binding activity, an in vitro evolution strategy was employed, wherein random mutations were introduced into the humanized VH domain by means of error-prone PCR, followed by a filter sandwich Escherichia coli colony screening assay for functional Fab fragments using a recombinant extracellular domain of the CD30 antigen. After three cycles of in vitro affinity maturation, the optimized Fab fragment huHRS3-VH-EP3/1 was identified, which carried four exchanged residues within or close to the VH CDRs and had an affinity that was almost identical with that of the murine HRS3 Fab fragment. The resulting humanized Fab fragment was fully functional with respect to CD30 binding both in ELISA with the recombinant antigen and in FACS experiments with CD30-positive L540CY cells. In the light of the previously successful clinical application of an alphaCD30 x alphaCD16 bispecific mouse quadroma antibody derived from HRS3, the humanized Fab fragment comprises an important step towards the construction of a fully recombinant therapeutic agent. The combination of random mutagenesis and colony filter screening assay that was successfully applied here should be generally useful as a method for the rapid functional optimization of humanized antibody fragments.

Local IL-13 gene transfer prior to immune-complex arthritis inhibits chondrocyte death and matrix-metalloproteinase-mediated cartilage matrix degradation despite enhanced joint inflammation

During immune-complex-mediated arthritis (ICA), severe cartilage destruction is mediated by Fcgamma receptors (FcgammaRs) (mainly FcgammaRI), cytokines (e.g. IL-1), and enzymes (matrix metalloproteinases (MMPs)). IL-13, a T helper 2 (Th2) cytokine abundantly found in synovial fluid of patients with rheumatoid arthritis, has been shown to reduce joint inflammation and bone destruction during experimental arthritis. However, the effect on severe cartilage destruction has not been studied in detail. We have now investigated the role of IL-13 in chondrocyte death and MMP-mediated cartilage damage during ICA. IL-13 was locally overexpressed in knee joints after injection of an adenovirus encoding IL-13 (AxCAhIL-13), 1 day before the onset of arthritis; injection of AxCANI (an empty adenoviral construct) was used as a control. IL-13 significantly increased the amount of inflammatory cells in the synovial lining and the joint cavity, by 30% to 60% at day 3 after the onset of ICA. Despite the enhanced inflammatory response, chondrocyte death was diminished by two-thirds at days 3 and 7. The mRNA level of FcgammaRI, a receptor shown to be crucial in the induction of chondrocyte death, was significantly down-regulated in synovium. Furthermore, MMP-mediated cartilage damage, measured as neoepitope (VDIPEN) expression using immunolocalization, was halved. In contrast, mRNA levels of MMP-3, -9, -12, and -13 were significantly higher and IL-1 protein, which induces production of latent MMPs, was increased fivefold by IL-13. This study demonstrates that IL-13 overexpression during ICA diminished both chondrocyte death and MMP-mediated VDIPEN expression, even though joint inflammation was enhanced.

Novel insights on human NK cells' immunological modalities revealed by gene expression profiling

As part of the innate immune system, human NK cells play a critical role early in the systemic host defense against pathogens and tumor cells. Recent studies suggest a more complex view of NK cell behavior, as different functions and tissue localizing capabilities seem to be preferentially assigned to distinct subpopulations of NK cells, CD56(dim)CD16(+) or CD56(bright)CD16(-). In this study, we used oligonucleotide microarrays to compare the expression profile of approximately 20,000 genes in three NK cell subpopulations: peripheral blood-derived CD56(dim)CD16(+), CD56(bright)CD16(-), and in vitro-activated CD16(+) NK cells. The differential expression of selected genes was verified by flow cytometry and functional assays. When comparing CD56(dim)CD16(+) and CD56(bright)CD16(-) subsets, a new heterogeneous molecular basis for the functional and developmental differences between these two subsets was revealed. Furthermore, systematic analysis of transcriptional changes in activated CD16(+) NK cells provided us with a better understanding of NK function in inflamed tissues. We highlight a number of genes that were overexpressed upon activation (e.g., OX40 ligand, CD86, Tim3, galectins, etc.), that enable these cells to directly cross-talk with other innate and adaptive immune effectors. The overexpressed genes assign novel intriguing immunomodulatory functions to activated NK cells, in addition to their potent cytotoxic abilities.

Early membrane events in polymorphonuclear cell (PMN) apoptosis: membrane blebbing and vesicle release, CD43 and CD16 down-regulation and phosphatidylserine externalization

CD43 down-regulation during the apoptosis of PMN (polymorphonuclear cells) is not caused by proteolysis or internalization. Could it be released with bleb-derived membrane vesicles? Membrane blebbing was followed by microscopy on PMN 'synchronized' by an overnight incubation at 15 degrees C before their spontaneous apoptosis at 37 degrees C. Released vesicles were quantified by flow cytometry. Membrane blebbing, release of bleb-derived membrane vesicles, decrease of CD43/CD16 expression and phosphatidylserine externalization occurred simultaneously. However, caspase and PKC inhibition prevented annexin binding but not blebbing, vesicle release or CD43 expression decrease; myosin light chain kinase inhibition prevented cell blebbing and vesicle release but had no effect on CD43/CD16 down-regulation or annexin V binding. By electron microscopy, CD43 appeared poorly expressed on membrane blebs and concentrated at bleb 'necks'. In conclusion, CD43 down-regulation is not caused by cell blebbing. Cell blebbing, phospholipid 'flip-flop' and CD43/CD16 down-regulation are independent membrane events.

Decrease of CD4+ T-lymphocytes in children exposed to environmental lead

The effects of environmental lead on the immune system of young children were assessed by determining the peripheral blood lymphocytes CD3+, CD4+, CD8+, B(CD19+) counts, and natural killer (CD16+CD56+) cells in 35 preschool children whose mean blood lead level was 140.6 microg/L. The results were compared to an age- and sex-matched control group with a mean blood lead level of 64.3 microg/L. Compared to the controls, a significant reduction in the percentage of CD4+ cells and a significant increase of CD8+ cells were seen in the high-lead group. The negative correlation between the percentage of CD4+ cells and blood lead levels was found to be significant (p<0.01). These results suggest that exposure to environmental lead might result in alterations in the immune function of young children.

Pathogen-induced apoptotic neutrophils express heat shock proteins and elicit activation of human macrophages

Ingestion of aged or irradiated apoptotic neutrophils actively suppresses stimulation of macrophages (Mphi). Many bacterial pathogens can also provoke apoptosis in neutrophils, but little is known about how such apoptotic cells influence Mphi activation. We found that neutrophils undergoing apoptosis induced by UV irradiation, Escherichia coli, or Staphylococcus aureus could either stimulate or inhibit Mphi activation. In contrast to Mphi that had ingested irradiated apoptotic neutrophils, Mphi that had phagocytosed bacteria-induced apoptotic neutrophils exhibited markedly increased production of the proinflammatory cytokine TNF-alpha, but not the anti-inflammatory cytokine TGF-beta. Moreover, ingestion of bacteria, but not UV-induced apoptotic neutrophils, caused increased expression of FcgammaRI on Mphi, and this effect was not provoked directly by bacteria associated with the apoptotic neutrophils. Instead, we found that a link between pathogen-induced apoptotic neutrophils and up-regulation of the heat shock proteins HSP60 and HSP70, and we also observed that recombinant HSP60 and HSP70 potentiated LPS-stimulated production of TNF-alpha in Mphi. The opposing macrophage responses to neutrophils undergoing apoptosis induced in different ways may represent a novel mechanism that regulates the extent of the immune response to invading microbes in two steps: first by aiding the functions of Mphi at an early stage of infection, and subsequently by deactivating those cells through removal of uninfected apoptotic neutrophils. HSP induction in neutrophils may provide the danger signals required to generate a more effective macrophage response.

Cytosolic phospholipase A2-alpha is necessary for platelet-activating factor biosynthesis, efficient neutrophil-mediated bacterial killing, and the innate immune response to pulmonary infection: cPLA2-alpha does not regulate neutrophil NADPH oxidase activity

The role of a cytosolic phospholipase A(2)-alpha (cPLA(2)-alpha) in neutrophil arachidonic acid release, platelet-activating factor (PAF) biosynthesis, NADPH oxidase activation, and bacterial killing in vitro, and the innate immune response to bacterial infection in vivo was examined. cPLA(2)-alpha activity was blocked with the specific cPLA(2)-alpha inhibitor, Pyrrolidine-1 (human cells), or by cPLA(2) -alpha gene disruption (mice). cPLA(2)-alpha inhibition or gene disruption led to complete suppression of neutrophil arachidonate release and PAF biosynthesis but had no effect on neutrophil NADPH oxidase activation, FcgammaII/III or CD11b surface expression, primary or secondary granule secretion, or phagocytosis of Escherichia coli in vitro. In contrast, cPLA(2)-alpha inhibition or gene disruption diminished neutrophil-mediated E. coli killing in vitro, which was partially rescued by exogenous arachidonic acid or PAF but not leukotriene B(4). Following intratracheal inoculation with live E. coli in vivo, pulmonary PAF biosynthesis, inflammatory cell infiltration, and clearance of E. coli were attenuated in cPLA(2)-alpha(-/-) mice compared with wild type littermates. These studies identify a novel role for cPLA(2)-alpha in the regulation of neutrophil-mediated bacterial killing and the innate immune response to bacterial infection.

Immunoglobulin G Fc(gamma) receptor expression on polymorphonuclear cells in bronchoalveolar lavage fluid of HIV-infected and HIV-seronegative patients with bacterial pneumonia

This study was designed to test the hypothesis that impaired neutrophil function might contribute to the development of bacterial pneumonia in patients with HIV-infection. Numbers of inflammatory cells and immunoglobulin G Fcgamma receptor (IgG FcgammaR) I, II, III levels were investigated in bronchoalveolar lavage (BAL) fluid of HIV-seronegative and HIV-infected patients with bacterial pneumonia. The 99 patients were classified into three groups: I: HIV-seronegative and pneumonia (n = 40); II: HIV-infected and pneumonia (n = 19); III: HIV-seronegative with other pulmonary diseases than pneumonia (n = 40). The results of groups I and II, II and III, and I and III were compared. The percentage of alveolar macrophages was significantly lower (group II vs. III: p = 0.005, group I vs. III: p = 0.001), that of neutrophils increased significantly in patients with pneumonia (group II vs. III: p = 0.02, group I vs. III: p = 0.01). Lymphocytes differed only between groups I and III (p = 0.04). Although only the expression of FcgammaRI was significantly higher in HIV-seronegative pneumonia patients compared to those without pneumonia (p = 0.01), the mean expression of all three receptors was lower in the HIV-infected group, with that of FcgammaRI approaching statistical significance. This report provides first evidence that altered FcgammaR expression on BAL neutrophils might contribute to the increased susceptibility of HIV-infected patients to bacterial pneumonia.

Tissue detection of natural killer cells in colorectal adenocarcinoma

BACKGROUND

Natural killer (NK) cells represent a first line of defence against a developing cancer; however, their exact role in colorectal cancer remains undetermined. The aim of the present study was to evaluate the expression of CD16 and CD57 [immunohistochemical markers of natural NK cells] in colorectal adenocarcinoma.

METHODS

Presence of NK cells was investigated in 82 colorectal adenocarcinomas. Immunohistochemical analysis was performed, using 2 monoclonal antibodies (anti-Fc Gamma Receptor II, CD16 and an equivalent to Leu-7, specific for CD-57). The number of immunopositive cells (%) was evaluated by image analysis. The cases were characterized according to: patient gender and age, tumor location, size, grade, bowel wall invasion, lymph node metastases and Dukes' stage.

RESULTS

NK cells were detected in 79/82 cases at the primary tumor site, 27/33 metastatic lymph nodes and 3/4 hepatic metastases; they were detected in levels similar to those reported in the literature, but their presence was not correlated to the clinical or pathological characteristics of the series, except for a negative association with the patients' age (p = 0.031).

CONCLUSIONS

Our data do not support an association of NK cell tissue presence with clinical or pathological variables of colorectal adenocarcinoma, except for a negative association with the patients' age; this might possibly be attributed to decreased adhesion molecule expression in older ages.

The novel cyclophilin-binding drug sanglifehrin A specifically affects antigen uptake receptor expression and endocytic capacity of human dendritic cells

Sanglifehrin A (SFA) is a recently developed immunosuppressant that belongs to the family of immunophilin-binding ligands. SFA is a cyclophilin A-binding immunosuppressive drug with a novel, but unidentified, mechanism of action. Several reports exist about the effect of SFA on T cells, but its effect on the initiators of the immune response, i.e., dendritic cells (DCs), is relatively unknown. Therefore, we examined the effect of SFA on the differentiation and function of human monocyte-derived DCs. Unlike the well-known cyclophilin A-binding immunosuppressant cyclosporin A, which did not affect DC phenotype, differentiation of DCs in the presence of SFA resulted in CD14-CD1a DCs with normal DC morphology, viability, and a proper capacity to activate allogeneic T cells. However, DCs generated in the presence of SFA demonstrated reduced macropinocytosis and lectin-mediated endocytosis, which was in line with a decreased expression of C-type lectins, including mannose receptor, C1qRP, DC-ASGPR, and especially, DC-SIGN. In contrast, FcalphaRI (CD89) and FcgammaRII (CD32) were increased by SFA. The explicit effect of SFA on the expression of Ag uptake receptors and Ag capture by DCs makes SFA unique among immunophilin-binding immunosuppressive drugs.

Flow cytometric detection of nonneoplastic antigenic polymorphisms of donor origin after allogeneic marrow transplant: a report of two cases

Multidimensional flow cytometry found an abnormal lack of CD16 expression detected on neutrophils after hematopoietic stem cell transplantation (HSCT) in bone marrow specimens from 2 patients. Chimerism studies were used to determine that the CD16- myeloid cells were donor in origin, consistent with a normal polymorphic variant, most likely a previously described Fc gamma receptor IIIB gene deletion. Identical phenotypes were recognized in peripheral blood samples obtained subsequently from the respective donors. These donor-specific phenotypic abnormalities were transferred to patients who underwent successful HSCT. The distinction of these phenotypic abnormalities from neoplastic changes such as secondary myelodysplasias or relapse of original disease is important in posttransplantation monitoring of hematopoietic diseases.

Expression of the lysophospholipid receptor family and investigation of lysophospholipid-mediated responses in human macrophages

Some of the biological effects of lipoproteins have been attributed to their association with lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), sphingosine-1-phosphate (S1P) and sphingosylphosphorylcholine (SPC). These lysophospholipids mediate multiple biological responses via several G protein-coupled receptors (GPR). The expression of these receptors, however, has not been systematically investigated in primary human monocytes and macrophages as major cells involved in atherosclerosis. The mRNAs for all 15 receptors described so far were detected in monocytes, macrophages, foam cells and high density lipoprotein (HDL(3))-treated cells using real time RT-PCR. Immunoblots revealed that S1P(1), S1P(2), S1P(4), LPA(1), LPA(2) and GPR65 are expressed in monocytes and macrophages, while S1P(5) and LPA(3) have not been detected. S1P(3) was induced during differentiation but down-regulated by lipid-loading and HDL(3), whereas LPA(1) was down-regulated in differentiated macrophages. The influence of S1P on macrophages was investigated and the induction of CD32 indicates an enhanced phagocytic activity. Altogether, these data give insights into the expression and regulation of lysophospholipid receptors in primary human monocytes, macrophages and foam cells.

Identification of unsuspected PNH-type cells in flow cytometric immunophenotypic analysis of peripheral blood and bone marrow

In this report, the flow cytometric expression patterns for CD14 on monocytic cells and CD16 on granulocytic cells in peripheral blood or bone marrow specimens are illustratedfor 15 patients proven to have a paroxysmal nocturnal hemoglobinuria (PNH) phenotype by flow cytometric analysis for CD55 and CD59. The varied clinical manifestations of PNH and its rarity may make it difficult to recognize clinically. As a result, blood or bone marrow samples may be submitted for flow cytometric analysis to exclude bone marrow neoplasia or dysplasia in patients with cytopenias rather than to exclude PNH. This was true in 5 of 15 study cases. Unlike CD55 and CD59, CD14 and/or CD16 are assessed routinely in the flow cytometric analysis of blood and bone marrow samples. Recognition of abnormal patterns of CD14 and CD16 expression might permit the identification of clinically unsuspected PNH by routine flow cytometric analysis.

The inositol 3-phosphatase PTEN negatively regulates Fc gamma receptor signaling, but supports Toll-like receptor 4 signaling in murine peritoneal macrophages

Fc gamma R clustering in macrophages activates signaling events that result in phagocytosis. Phagocytosis is accompanied by the generation harmful byproducts such as reactive oxygen radicals and production of inflammatory cytokines, which mandate that the phagocytic process be subject to a tight regulation. The molecular mechanisms involved in this regulation are not fully understood. In this study, we have examined the role of the inositol 3-phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in Fc gamma R-induced macrophage function. We demonstrate that in ex vivo murine peritoneal macrophages that are deficient in PTEN expression, Fc gamma R-induced Akt and extracellular signal-regulated kinase phosphorylation are enhanced. Notably, PTEN(-/-) macrophages showed constitutively high phosphorylation of Akt. However, PTEN did not seem to influence tyrosine phosphorylation events induced by Fc gamma R clustering. Furthermore, PTEN(-/-) macrophages displayed enhanced phagocytic ability. Likewise, Fc gamma R-induced production of TNF-alpha, IL-6, and IL-10 was significantly elevated in PTEN(-/-) macrophages. Surprisingly, LPS-induced TNF-alpha production was down-regulated in PTEN(-/-) macrophages. Analyzing the molecular events leading to PTEN influence on LPS/Toll-like receptor 4 (TLR4) signaling, we found that LPS-induced activation of mitogen-activated protein kinases is suppressed in PTEN(-/-) cells. Previous reports indicated that LPS-induced mitogen-activated protein kinase activation is down-regulated by phosphatidylinositol 3-kinase through the activation of Akt. Our observation that Akt activation is basally enhanced in PTEN(-/-) cells suggests that PTEN supports TLR4-induced inflammatory responses by suppressing the activation of Akt. Thus, we conclude that PTEN is a negative regulator of Fc gamma R signaling, but a positive regulator of TLR4 signaling. These findings are the first to demonstrate a role for PTEN in Fc gamma R- and TLR4-mediated macrophage inflammatory response.

IGG and complement receptor expression on peripheral white blood cells in uraemic children

BACKGROUND

Phagocytosis of IgG- or complement-opsonized bacteria and antibody production by lymphocytes are regulated by cell surface receptors for IgG (FcgammaRI, FcgammaRII and FcgammaRIII) and complement (CR1 and CR3). We measured the effect of uraemia and dialysis treatment on FcgammaR and CR expression on leukocytes in blood.

METHODS

Blood samples were obtained from children: 40 treated with peritoneal dialysis (PD), 23 with haemodialysis (HD), 46 not yet dialysed (CRF) and 33 healthy (HC). White blood cells, isolated from EDTA-blood by centrifugation after cell fixation with paraformaldehyde, were labelled with FITC-conjugated CD16 (FcgammaRIII), CD32 (FcgammaRII), CD64 (FcgammaRI), CD11b (CR3) and CD35 (CR1) monoclonal antibodies and analysed by flow cytometry.

RESULTS

In PD, HD, CRF and HC, monocytes and neutrophils were all positive for FcgammaR and CR, except for CD16 on monocytes (20% positive). Lymphocytes expressed CD16 and CD32 but not CD64. PD, HD and CRF children had lower percentages of CD16(+) and CD32(+) lymphocytes compared with HC. The percentage of CD11b(+) lymphocytes was lower only in PD and the percentage of CD35(+) lymphocytes was lower in HD and CRF compared with HC. The median CD32 mean fluorescense intensity (MFI) on lymphocytes, monocytes and neutrophils was lower in PD, HD and CRF compared with HC. On the other hand, CD11b MFI on lymphocytes, monocytes and neutrophils was higher in PD, HD and CRF children compared with HC. CD16 and CD64 MFI were not different among the groups and CD35 MFI was only lower on lymphocytes from PD, HD and CRF compared with HC.

CONCLUSIONS

In children with chronic renal failure, whether dialysed or not, FcgammaRII expression on lymphocytes, monocytes and neutrophils was reduced and CR3 expression was increased. Furthermore, CR1 expression on lymphocytes, important for the humoral response, was lower in children with renal failure. Age and uraemia are associated with these abnormalities and might contribute to impaired immune function in children with chronic renal failure.

The acute response of neutrophil function to a bout of judo training

Intensive exercise training decreases neutrophil functions in athletes. However, no studies to date have investigated the effect of irregular-interval training, such as is associated with judo training programmes, on neutrophil functions. The purpose of this study was to examine such effects. Thirty-seven male college judoists participated in this study. Neutrophil oxidative burst activity, phagocytic activity and expression of CD11b and CD16 per cell were measured by fl ow cytometry before and after judo training. Total neutrophil counts increased significantly from 2.98 +/- 0.82 to 7.95 +/- 1.80 x 10(3)/ microL (p < 0.001). The proportion of neutrophils producing reactive oxygen species (ROS) was increased significantly (p < 0.001). On the other hand, the phagocytic activity decreased after training, as shown by a decrease in the amount of ingested opsonized zymosan per cell (p < 0.001), possibly as a compensatory effect for the increased numbers of ROS-producing neutrophils. Expression of CD11b and CD16 per cell decreased by 20% and 30%, respectively, after judo training. In conclusion, judo training induced a decrease in phagocytic activity through the lowered expression of CD11b and CD16 on the surface of neutrophils, and increased the oxidative burst activity of neutrophils.

Post-traumatic osteomyelitis: analysis of inflammatory cells recruited into the site of infection

Device-associated infections after implants or endoprostheses inflict local inflammation and ultimately osteolysis, a clinical entity referred to as posttraumatic osteomyelitis. The underlying molecular mechanisms are not yet known; formation of bacterial biofilms on the implant is presumed, conferring resistance to antibiotics and to host defense mechanisms as well. To gain insight into the pathogenesis of post-traumatic osteomyelitis, the infected site was analyzed for the presence of immunocompetent cells. In 18 patients, the infected site was rinsed intraoperatively. This so-called lavage contained 1-2 x 107 leukocytes, predominantly highly activated polymorphonuclear neutrophils (PMNs), as characterized by low expression of CD62L (selectin), and high expression of the adhesion protein CD18, of the high-affinity immunoglobulin (IgG) receptor CD64, and of the LPS-receptor CD14. CD16, the low-affinity IgG receptor, was affected in some patients only. Because the majority of infections were caused by staphylococci species, the effect of bacteria-derived lipoteichoic acid on PMN of healthy donors was tested in vitro. A similar activation pattern was found: rapid down-regulation of CD62L, a slower loss of CD16, and upregulation of CD18, CD64, and CD14. Lipoteichoic acid signaling required p38 mitogen-activated protein kinase and resulted in induction of CD14-specific mRNA and de novo protein synthesis. We conclude that PMNs infiltrate the infected site, but despite local activation they are unable to clear the bacteria, presumably because of biofilm formation. Our data are consistent with the hypothesis that during the ineffective "frustrated" attempt to phagocytose, PMNs release cytotoxic and proteolytic entities that in turn contribute to the progression of tissue injury and ultimately to osteolysis.