A rare occurrence of Anaplasma-associated peritonitis

Anaplasmosis or human granulocytic anaplasmosis is a tick-borne illness caused by the bacteria, Anaplasma phagocytophilum, resulting from an infected tick bite. Examination of a blood smear within the first week of exposure may show microcolonies of anaplasmae (morulae) in the cytoplasm of neutrophils that are highly suggestive of anaplasmosis but not definitive. We present the first case describing Anaplasma-related peritonitis and morulae in peritoneal fluid granulocytes in a peritoneal dialysis patient who developed anaplasmosis.

Eosinophils are part of the granulocyte response in tuberculosis and promote host resistance in mice

Host resistance to Mycobacterium tuberculosis (Mtb) infection requires the activities of multiple leukocyte subsets, yet the roles of the different innate effector cells during tuberculosis are incompletely understood. Here we uncover an unexpected association between eosinophils and Mtb infection. In humans, eosinophils are decreased in the blood but enriched in resected human tuberculosis lung lesions and autopsy granulomas. An influx of eosinophils is also evident in infected zebrafish, mice, and nonhuman primate granulomas, where they are functionally activated and degranulate. Importantly, using complementary genetic models of eosinophil deficiency, we demonstrate that in mice, eosinophils are required for optimal pulmonary bacterial control and host survival after Mtb infection. Collectively, our findings uncover an unexpected recruitment of eosinophils to the infected lung tissue and a protective role for these cells in the control of Mtb infection in mice.

Proliferation and differentiation of circulating haemocytes of Ruditapes philippinarum as a response to bacterial challenge

Ultrastructural investigation confirmed the presence of four cell types (granulocytes, hyalinocytes, serous cells, and haemoblasts) in the haemolymph of the Manila clam, Ruditapes philippinarum. Granulocytes were characterised by numerous electron-dense granules, whereas hyalinocytes had a considerable number of small clear vesicles. Serous cells exhibited large vacuoles, which filled the cytoplasm, and haemoblasts (the undifferentiated cells) were small roundish cells characterised by a high nucleus/cytoplasm ratio. The presence of circulating haemoblasts was observed at various phases of mitosis. Updated data concerning the proliferation and differentiation of circulating haemocytes were obtained after both in vitro and in vivo bacterial challenge. The results demonstrated that cell proliferation occurred within 15 h of exposure, and most haemocyte types responded to the stimuli. The number of granulocytes significantly decreased after massive phagocytosis and ultrastructural observations confirmed that they were active phagocytic cells against both Gram-positive and Gram-negative bacteria, which were rapidly engulfed into large phagosomes. Granulocyte lysis may represent a protection response against bacterial proliferation inside phagosomes. The number of serous cells significantly increased, suggesting a previously unreported pivotal immune role during bacterial infection. A panel of lectins was used as probes to further characterise haemocytes and their relationships. Only hyalinocytes were not positive for the lectins assayed, whereas all lectins labelled serous cells, suggesting that these cells have a variety of specific carbohydrates, which are shared with certain haemoblasts. The hypothesis of the existence of a prospective haemoblast for serous cell origin is discussed.

Characterization of pathogenesis of and immune response to Burkholderia pseudomallei K96243 using both inhalational and intraperitoneal infection models in BALB/c and C57BL/6 mice

Burkholderia pseudomallei, the etiologic agent of melioidosis, is a Gram negative bacterium designated as a Tier 1 threat. This bacterium is known to be endemic in Southeast Asia and Northern Australia and can infect humans and animals by several routes. Inhalational melioidosis has been associated with monsoonal rains in endemic areas and is also a significant concern in the biodefense community. There are currently no effective vaccines for B. pseudomallei and antibiotic treatment can be hampered by non-specific symptomology and also the high rate of naturally occurring antibiotic resistant strains. Well-characterized animal models will be essential when selecting novel medical countermeasures for evaluation prior to human clinical trials. Here, we further characterize differences between the responses of BALB/c and C57BL/6 mice when challenged with low doses of a low-passage and well-defined stock of B. pseudomallei K96243 via either intraperitoneal or aerosol routes of exposure. Before challenge, mice were implanted with a transponder to collect body temperature readings, and daily body weights were also recorded. Mice were euthanized on select days for pathological analyses and determination of the bacterial burden in selected tissues (blood, lungs, liver, and spleen). Additionally, spleen homogenate and sera samples were analyzed to better characterize the host immune response after infection with aerosolized bacteria. These clinical, pathological, and immunological data highlighted and confirmed important similarities and differences between these murine models and exposure routes.

Epithelial IL-23R Signaling Licenses Protective IL-22 Responses in Intestinal Inflammation

A plethora of functional and genetic studies have suggested a key role for the IL-23 pathway in chronic intestinal inflammation. Currently, pathogenic actions of IL-23 have been ascribed to specific effects on immune cells. Herein, we unveil a protective role of IL-23R signaling. Mice deficient in IL-23R expression in intestinal epithelial cells (Il23R(ΔIEC)) have reduced Reg3b expression, show a disturbed colonic microflora with an expansion of flagellated bacteria, and succumb to DSS colitis. Surprisingly, Il23R(ΔIEC) mice show impaired mucosal IL-22 induction in response to IL-23. αThy-1 treatment significantly deteriorates colitis in Il23R(ΔIEC) animals, which can be rescued by IL-22 application. Importantly, exogenous Reg3b administration rescues DSS-treated Il23R(ΔIEC) mice by recruiting neutrophils as IL-22-producing cells, thereby restoring mucosal IL-22 levels. The study identifies a critical barrier-protective immune pathway that originates from, and is orchestrated by, IL-23R signaling in intestinal epithelial cells.

[EPIDEMIOLOGIC ASPECTS OF HUMAN GRANULOCYTIC ANAPLASMOSIS IN THE WESTERN REGION OF UKRAINE]

This article presents data of complex study of human granulocytic anaplasmosis the human granulocytic anaplasmosis (HGA) in the western region of Ukraine. Natural HGA foci were identified, where the prevalence of A. phagocytophilum in the main vector (I. ricinus) amount to (12.0 +/- 0.7) %, and seroprevalence of HGA among the healthy population--(28.6 +/- 1.6) %. It's shown that A. phagocytophilum is the etiologic agent of (33.7 +/- 4.9) % of undiagnosed cases of seasonal febrile diseases. Principal characteristics of HGA epidemiology: spring-summer scasonality, the prevalence of disease in the age structure of people of active age (45.30 +/- 1.95 years), a significant level combination with (60.4 +/- 2.2) % Lyme-horreliosis and other tick-borne infections (mixed infections), the different level of activity of HGA epidemic process in forest and steppe geographical landscape zones--were revealed.

A continuous cell line, SYSU-OfHe-C, from hemocytes of Ostrinia furnacalis possesses immune ability depending on the presence of larval plasma

A continuous cell line, SYSU-OfHe-C, from larval hemocytes of corn borer, Ostrinia furnacalis was established. With increasing passages, the cells grew increasingly faster, and approximately 45% of the cells were in division at passage 55. The culture was mainly composed of two types of cells, granulocytes and plasmatocytes, which showed different division and proliferation behaviors, but possessed similar phagocytic ability. Its spreading ability was significantly weaker than that of hemocytes from naïve larva; however, it could be promoted by larval plasma. Furthermore, its encapsulation ability was also promoted by larval plasma to form multilayer capsules on Sephadex A-25 beads. Finally, the expression of several immune-related genes was verified after provocation by microbes or Sephadex beads. These results indicated that the cell line possessed immune ability depending on the presence of plasma of naïve larvae and are beneficial to studies of insect cellular systems.

Probiotic Lactobacillus strains protect against myelosuppression and immunosuppression in cyclophosphamide-treated mice

This work evaluated the capacity of two probiotic strains, Lactobacillus casei CRL431 and Lactobacillus rhamnosus CRL1506, to protect against myelosuppression and immunosuppression in cyclophosphamide (Cy)-treated mice. Changes in mature granulocytes and progenitor cells in bone marrow (BM) and blood were studied. In addition, the ability of probiotics to accelerate the recovery of the immune response against the opportunistic pathogen Candida albicans was evaluated. We demonstrated for the first time that the preventive treatment with immunomodulatory lactobacilli such as L. casei CRL431 or L. rhamnosus CRL1506 was able to increase immature myeloid progenitors in the BM, allowing an early recovery of myeloid cells after Cy administration. Probiotic lactobacilli were also capable to induce an early recovery of neutrophils in blood, improve phagocytic cells recruitment to infectious sites and increase the resistance against the opportunistic pathogen C. albicans. Although deeper studies regarding the cellular and molecular mechanisms of probiotic actions are needed, these findings support the idea that strains like CRL431 and CRL1506 may accelerate the recovery of Cy-caused immunosuppression by immunopotentiating myeloid cells. Then, probiotic lactobacilli have the potential to be used as alternatives for lessening chemotherapy-induced immunosuppression in cancer patients.

ATG16L1 and NOD2 polymorphisms enhance phagocytosis in monocytes of Crohn’s disease patients

AIM: To investigate if the presence of relevant genetic polymorphisms has effect on the effectual clearance of bacteria by monocytes and granulocytes in patients with Crohn’s disease (CD).

METHODS: In this study, we assessed the differential responses in phagocytosis by measuring the phagocytic activity and the percentage of active phagocytic monocytes and granulocytes in inflammatory bowel disease patients as well as healthy controls. As both autophagy related like 1 (ATG16L1) and immunity-related guanosine triphosphatase gene are autophagy genes associated with CD and more recently nucleotide-binding ligomerization domain-containing protein 2 (NOD2) has been identified as a potent inducer of autophagy we genotyped the patients for these variants and correlated this to the phagocytic reaction. The genotyping was done with restriction fragment length polymorphisms analysis and the phagocytosis was determined with the pHrodo™Escherichia coli Bioparticles Phagocytosis kit for flowcytometry.

RESULTS: In this study, we demonstrate that analysis of the monocyte and granulocyte populations of patients with CD and ulcerative colitis showed a comparable phagocytic activity (ratio of mean fluorescence intensity) between the patient groups and the healthy controls. CD patients show a significantly higher phagocytic capacity (ratio mean percentage of phagocytic cells) compared to healthy controls (51.91% ± 2.85% vs 37.67% ± 7.06%, P = 0.05). The extend of disease was not of influence. However, variants of ATG16L1 (WT: 2.03 ± 0.19 vs homozygoot variant: 4.38 ± 0.37, P < 0.009) as well as NOD2 (C-ins) (heterozygous variant: 42.08 ± 2.94 vs homozygous variant: 75.58 ± 4.34 (P = 0.05) are associated with the phagocytic activity in patients with CD.

CONCLUSION: Monocytes of CD patients show enhanced phagocytosis associated with the presence of ATG16L1 and NOD2 variants. This could be part of the pathophysiological mechanism resulting in the disease.

[Peculiarities of microbiological and immunological indices of human nose mucosa in conditions of man-made pollution]

Possible influence of man-made load on formation and function of microbiocenosis of the nose mucosa in practically healthy people of industrial city has been studied. Microbiota composition, content of secretory immunoglobulin A, functional state and expression of TLR-2 and TLR-4 by mucosa cells were studied in the given human biotope. The residing in conventionally contaminated districts of the industrial city tells on the increase of ecologic role of Candida albicans in the composition of microbiocenosis of the nose mucosa. The authors have shown high sensitivity of the number of TLR-4-positive epithelial cells to the type of the basic taxon of a microorganism in the composition of the nose mucosa microbiota and also sensitivity of the number of TLR-2 and TLR-4-positive epithelial cells and the density of expression by TLR-4 epithelial cells to the man-made pollution, they have also established the expressed unbalance of the system of inherent immunity of the nose mucosa of practically healthy young persons in conditions of man-made pollution.

Molecular diagnosis of human granulocytic anaplasmosis

Human granulocytic anaplasmosis, formerly known as human granulocytic ehrlichiosis, is caused by the microorganism Anaplasma phagocytophilum that is transmitted by Ixodes tick bites. The disease state ranges from subclinical to fatal but may be difficult to differentiate from other febrile conditions without specific tests. Rapid and early diagnosis is important since the infection may be fatal and specific antibiotic therapy is required. The bacterium is an obligate intracellular pathogen of neutrophils. Thus, early diagnosis is best achieved by amplification of nucleic acids from the blood. An increasing number of potential gene targets for diagnostic assays have been described and the incipient release of an Anaplasma phagocytophilum genome sequence will not only help to better understand the disease but may facilitate improvements in diagnostic strategies.

Seroprevalence of human granulocytotropic anaplasmosis in central and southeastern China

Human granulocytic anaplasmosis (HGA) is an emerging tick-borne infectious disease. To determine the prevalence of HGA in central and southeastern China, a total of 323 human sera were collected from individuals at high risk for exposure to ticks and animals. The IgG antibody against the etiologic agent of HGA, Anaplasma phagocytophilum was detected with indirect immunofluorescence assay. The results showed that 20% of the tested individuals (64/323) were positive to A. phagocytophilum and that the incidence was higher in male (22%) than female (16%). We concluded that A. phagocytophilum infection was prevalent in central and southeastern China.

Chlamydia pneumoniae hides inside apoptotic neutrophils to silently infect and propagate in macrophages

BACKGROUND

Intracellular pathogens have developed elaborate strategies for silent infection of preferred host cells. Chlamydia pneumoniae is a common pathogen in acute infections of the respiratory tract (e.g. pneumonia) and associated with chronic lung sequelae in adults and children. Within the lung, alveolar macrophages and polymorph nuclear neutrophils (PMN) are the first line of defense against bacteria, but also preferred host phagocytes of chlamydiae.

METHODOLOGY/PRINCIPAL FINDINGS

We could show that C. pneumoniae easily infect and hide inside neutrophil granulocytes until these cells become apoptotic and are subsequently taken up by macrophages. C. pneumoniae infection of macrophages via apoptotic PMN results in enhanced replicative activity of chlamydiae when compared to direct infection of macrophages, which results in persistence of the pathogen. Inhibition of the apoptotic recognition of C. pneumoniae infected PMN using PS- masking Annexin A5 significantly lowered the transmission of chlamydial infection to macrophages. Transfer of apoptotic C. pneumoniae infected PMN to macrophages resulted in an increased TGF-ss production, whereas direct infection of macrophages with chlamydiae was characterized by an enhanced TNF-alpha response.

CONCLUSIONS/SIGNIFICANCE

Taken together, our data suggest that C. pneumoniae uses neutrophil granulocytes to be silently taken up by long-lived macrophages, which allows for efficient propagation and immune protection within the human host.

The antimicrobial peptides piscidins are stored in the granules of professional phagocytic granulocytes of fish and are delivered to the bacteria-containing phagosome upon phagocytosis

Antimicrobial peptides (AMPs) are increasingly recognized as a critical first line of defence against many pathogens. The genes encoding these peptides are expressed in numerous tissue and cell types from a wide variety of different species including mammals, amphibians, fish, and insects. In this study, we report that the AMPs called piscidins were primarily present in the mast cells (MCs) of fish and were only identified in fish belonging to the Order Perciformes. It is striking that histamine was seen to have a similar evolutionary history, since the only piscine MCs endowed with this molecule are in the Perciformes. We also show that both MCs and professional phagocytic granulocytes were armed with different piscidin molecules. In contrast, macrophages were devoid of these AMPs. More importantly, we found by immunoelectron microscopy that piscidins were delivered to the bacteria-containing phagosome of granulocytes upon phagocytosis, suggesting a role for these AMPs in the killing of both extracellular and intracellular pathogenic bacteria.

Granulocyte chemotactic properties of M. tuberculosis versus M. bovis-infected bovine alveolar macrophages

The incidence of bovine tuberculosis (TB) continues to rise, and causes significant economic losses worldwide. The causative agent of bovine TB, Mycobacterium bovis, is closely related to the human pathogen M. tuberculosis, and yet these two organisms differ profoundly in their ability to cause disease in cattle. The innate immune system is primarily responsible for controlling disease, with the alveolar macrophage (AlvMvarphi) acting as one of the first points of contact between host and respiratory pathogens. In this study we have examined some of the differences in this component of the host immune response to M. bovis and M. tuberculosis, with the aim of improving our understanding of why M. bovis is able to cause disease in cattle whereas M. tuberculosis is efficiently controlled. Initial studies using microarray technology revealed that chemokines represented some of the most differentially expressed genes between M. tuberculosis and M. bovis-infected bovine AlvMvarphi. M. tuberculosis-infected bovine AlvMvarphi expressed significantly higher levels of the chemokines CCL3, CCL4, CCL5 and CXCL8, whereas M. bovis-infected AlvMvarphi were shown to express higher levels of CCL23. We further demonstrated the role of chemokines in bovine TB by showing that supernatants from AlvMvarphi infected with M. tuberculosis were significantly more effective than those from M. bovis-infected cells at attracting bovine granulocytes in an in vitro chemotaxis assay. These results have significant implications in vivo as they suggest that the M. bovis-infected macrophage is able to circumvent activation of the host chemotactic response and thereby evade killing by the host immune system.

Toll-like receptor 2 impairs host defense in gram-negative sepsis caused by Burkholderia pseudomallei (Melioidosis)

BACKGROUND

Toll-like receptors (TLRs) are essential in host defense against pathogens by virtue of their capacity to detect microbes and initiate the immune response. TLR2 is seen as the most important receptor for gram-positive bacteria, while TLR4 is regarded as the gram-negative TLR. Melioidosis is a severe infection caused by the gram-negative bacterium, Burkholderia pseudomallei, that is endemic in Southeast Asia. We aimed to characterize the expression and function of TLRs in septic melioidosis.

METHODS AND FINDINGS

Patient studies: 34 patients with melioidosis demonstrated increased expression of CD14, TLR1, TLR2, and TLR4 on the cell surfaces of monocytes and granulocytes, and increased CD14, TLR1, TLR2, TLR4, LY96 (also known as MD-2), TLR5, and TLR10 mRNA levels in purified monocytes and granulocytes when compared with healthy controls. In vitro experiments: Whole-blood and alveolar macrophages obtained from TLR2 and TLR4 knockout (KO) mice were less responsive to B. pseudomallei in vitro, whereas in the reverse experiment, transfection of HEK293 cells with either TLR2 or TLR4 rendered these cells responsive to this bacterium. In addition, the lipopolysaccharide (LPS) of B. pseudomallei signals through TLR2 and not through TLR4. Mouse studies: Surprisingly, TLR4 KO mice were indistinguishable from wild-type mice with respect to bacterial outgrowth and survival in experimentally induced melioidosis. In contrast, TLR2 KO mice displayed a markedly improved host defenses as reflected by a strong survival advantage together with decreased bacterial loads, reduced lung inflammation, and less distant-organ injury.

CONCLUSIONS

Patients with melioidosis displayed an up-regulation of multiple TLRs in peripheral blood monocytes and granulocytes. Although both TLR2 and TLR4 contribute to cellular responsiveness to B. pseudomallei in vitro, TLR2 detects the LPS of B. pseudomallei, and only TLR2 impacts on the immune response of the intact host in vivo. Inhibition of TLR2 may be a novel treatment strategy in melioidosis.

Candida albicans aggravates duodenal ulcer perforation induced by administration of cysteamine in rats

BACKGROUND

Candida sp are frequently isolated from the ascitic fluid of patients with perforated ulcers. The present study was performed to examine whether Candida infection may be involved in the process of ulcer perforation.

METHODS

Male Wistar rats were divided into a saline group (n = 15) and a Candida group (n = 17). Cysteamine-HCl (Sigma; 31 mg/100 g) was administered thrice on day 1 to both groups of animals. Candida albicans at a density of 10(8) in 0.5 mL of saline was administered 1 h before, and 12 h and 24 h after the first administration of cysteamine in the Candida group.

RESULTS

Perforated duodenal ulcers were observed in 94.1% of the rats in the Candida group, but only 26.7% of the rats in the saline group (P < 0.01). The area of the duodenal ulcers in the Candida group was 40.89 +/- 33.07 mm2, whereas that in the saline group was 16.53 +/- 20.4 mm2 (P < 0.05). The mortality rate was significantly higher in the Candida group than in the saline group. In the Candida group, colonization by C. albicans was recognized at the ulcer base, surrounded by marked granulocytic infiltration. The number of eosinophils infiltrating the ulcer base was also significantly greater in the Candida group than in the saline group. Immunohistochemical analysis revealed the expression of secretory aspartyl protease (SAP) in the region of the ulcer showing colonization by C. albicans in the Candida group.

CONCLUSION

Candida albicans aggravates duodenal ulcer perforation in the experimental model of cysteamine-induced duodenal ulcer perforation. The present findings suggest that SAP and host-parasite relationships, including granulocyte-dependent mechanisms, may be involved in the aggravation of ulcer perforation by C. albicans.

Glycosyl-phosphatidyl-inositol-defective granulocytes from paroxysmal nocturnal haemoglobinuria patients show increased bacterial ingestion but reduced respiratory burst induction

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by the emergence of a GPI-defective clonal hematopoiesis. Its clinical features are hemolytic anemia, cytopenia, and thrombosis. Circulating monocytes and granulocytes are largely GPI-defective in PNH patients. This study aims to investigate the granulocyte functional properties in PNH. We analyzed bacterial-dependent intracellular ingestion and the consequent activation of oxidative burst in GPI-defective granulocytes from four neutropenic PNH patients. Our data show a significant increase in the ability of GPI-defective granulocytes to ingest opsonized bacteria. In addition, an impaired respiratory burst effectiveness in response to two independent bacterial stimuli, the N-formyl-MetLeuPhe (fMLP) synthetic bacterial peptide and E. coli, was revealed. The occurrence of neutropenia and the severe impairment of oxidative burst, occurring in chronic granulomatosis disease, were unable to significantly affect phagocytosis. Thus, additional mechanisms, able to differentially affect ingestion ability and respiratory burst effectiveness, have to be hypothesized. The reduced burst effectiveness of GPI-defective granulocytes was maintained after treatment with phorbol 12-myristate 13-acetate, a pharmacological stimulus able to extensively recruit and to trigger intracellular protein kinase C (PKC). Moreover, blocking of PKC has been observed to severely affect granulocyte respiratory burst with a mild effect on the phagocytosis. These data suggest a role for a modulation of intracellular PKC in the pathogenesis of the impaired granulocyte oxidative burst.

Clinical Diagnosis and Treatment of Human Granulocytotropic Anaplasmosis

Tick-borne rickettsiae in the genera Ehrlichia and Anaplasma are intracellular bacteria that infect wild and domestic mammals and, more recently, man. The increased desire of humans for recreational activities outdoors has increased the exposure to potential human pathogens that previously cycled almost exclusively within natural, nonhuman enzootic hosts. Anaplasma phagocytophilum causes an acute, nonspecific febrile illness of humans previously known as human granulocytotropic ehrlichiosis (HGE) and now called human granulocytotropic anaplasmosis (HGA). The first patient to have recognized HGA was hospitalized at St Mary's Hospital in Duluth, Minnesota, USA in 1990. However, the clinical and laboratory presentation of this infection remained undefined until 1994, when Bakken and collaborators published their experience with 12 patients who had HGA. By the end of December 2004, at least 2,871 cases of HGA had been reported from 13 U.S. states to the Centers for Disease Control and Prevention (CDC). A limited number of laboratory-confirmed cases have been reported from countries in Europe, including Austria, Italy, Latvia, the Netherlands, Norway, Poland, Slovenia, Spain, and Sweden. Ixodes persulcatus-complex ticks are the arthropod hosts for Borrelia burgdorferi, the agent of Lyme borreliosis, and are also the arthropod hosts for A. phagocytophilum. Most cases of HGA have been contracted in geographic regions that are endemic for Lyme borreliosis. Male patients outnumber female patients by a factor of 3 to 1 and as many as 75% of patients with HGA have had a tick bite prior to their illness. Seroepidemiologic studies have demonstrated that HGA for the most part is a mild or even asymptomatic illness. However, older individuals and patients who are immunocompromised by natural disease processes or medications may develop an acute, influenza-like illness characterized by high fever, rigors, generalized myalgias, and severe headache. Local skin reactions at the site of the tick bite have not been described, and nonspecific skin rashes have been reported only occasionally. Anaplasmosis is associated with variable but suggestive changes in routine laboratory test parameters. Most patients develop transient reductions in total leukocyte and platelet concentrations. Relative granulocytosis accompanied by a left shift and lymphopenia during the first week of illness has been reported frequently. Serum hepatic transaminase concentrations usually increase two- to fourfold, and inflammatory markers, such as C-reactive protein and the erythrocyte sedimentation rate, rise during the acute phase. Abnormal laboratory findings may return toward normal range for patients who have been ill for more than 7 days, which may obfuscate the clinical decision making. Characteristic clusters of bacteria (morulae) are observed in the cytoplasm of peripheral blood granulocytes in 20% to 80% of infected patients during the acute phase of illness. The clinical diagnosis may be confirmed retrospectively by specific laboratory tests, which include positive polymerase chain reaction (PCR), identification of A. phagocytophilum in culture of acute-phase blood, or the detection of specific antibodies to A. phagocytophilum in convalescent serum. Virtually all patients have developed serum antibodies to A. phagocytophilum after completion of antibiotic therapy, and demonstration of seroconversion by indirect immunofluorescent antibody testing of acute-phase and convalescent-phase serum samples is currently the most sensitive and specific tool for laboratory confirmation of HGA. Treatment with doxycycline usually results in rapid improvement and cure. Most patients with HGA have made an uneventful recovery even without specific antibiotic therapy. However, delayed diagnosis in older and immunocompromised patients may place those individuals at risk for an adverse outcome, including death. Thus, prompt institution of antibiotic therapy is advocated for any patient who is suspected to have HGA and for all patients who have confirmed HGA.

Comparison of binding and effects of Escherichia coli Shiga toxin 1 on bovine and ovine granulocytes

Granulocytes play a pivotal role in the pathogenesis of Shiga toxin (Stx)-producing Escherichia coli (STEC) related diseases in humans. Granulocytes are attracted and activated by Stxs in the enteric mucosa and are believed to thereby contribute to the intestinal inflammation. Mature ruminants, the main reservoir hosts of STEC, do not develop pathological changes that can be attributed to the Stxs. To prove whether the latter phenomenon correlates with the inability of the Stxs to affect granulocytes of ruminants, we investigated the ability of Stx1 to bind to granulocytes of cattle and sheep and analysed the effects of Stx1 on viability, phagocytosis, and oxidative burst activity. Bovine granulocytes from blood and milk did not express Stx1-binding sites even after activation of the cells and also were resistant to Stx1. In contrast to bovine granulocytes, granulocytes of sheep constitutively expressed Stx1-receptors of the Gb(3)/CD77 type ex vivo and bound the recombinant B-subunit of Stx1 (rStxB1). Stx1 holotoxin induced apoptosis in ovine granulocytes after prolonged incubation (18h) but Stx1 only slightly altered the phagocytosis and oxidative burst activities. The rStxB1 had no effect on granulocytes of either species. While arguing in favour of our initial hypothesis, that granulocytes of both, cattle and sheep are not activated by Stxs, the results of our study are the first evidences for differences in the cellular distribution of Stx-receptors in species equally regarded as STEC carriers.

Immunological characterization and antibacterial function of persisting granulocytes in leukemic patients receiving pulse cytosine arabinoside-consolidation chemotherapy on days 1, 3, and 5

High-dose cytosine arabinoside (HiDAC) and intermediate-dose cytosine arabinoside (IDAC) have been introduced as effective and safe consolidation chemotherapy in acute myeloid leukemia, with relatively low rates of life-threatening infections despite the high total dose of the cytostatic drug. To explore the biological background of low toxicity, we examined the numbers, immunophenotype, and functional properties of granulocytes in patients with acute myeloid leukemia receiving HiDAC or IDAC. Interestingly, the absolute numbers of neutrophils remained >500/microl until day 10 in 92 of 125 (74%) HiDAC cycles and in 106 of 113 (94%) IDAC cycles. As assessed by electron microscopy, these day-10 granulocytes surviving chemotherapy were found to be mature cells containing secondary granules and phagolysosomes. They also expressed opsonization- and phagocytosis-linked surface Ags (C3biR, CR1, C1qR, C5aR, FcgammaRI, FcgammaRII, FcgammaRIII, and G-CSF and GM-CSF receptors) like neutrophils in healthy controls. Moreover, these day-10 neutrophils exhibited oxidative burst activity and took up and digested bacteria in the same way as neutrophils in healthy controls. There was a negative correlation between absolute neutrophil counts and severe infections in HiDAC- and IDAC-treated patients with a later onset of infections in IDAC patients (median: IDAC, day 18; HiDAC, day 16). Together, functionally mature neutrophils are detectable at least until day 10 in patients treated with HiDAC or IDAC, and may explain the relatively low hematologic toxicity of these consolidation protocols. IDAC is a superior protocol in this regard and may therefore be most suitable for elderly patients and those at high risk for severe infections.

Effects of a collagenolytic cell wall component from Fusobacterium necrophorum subsp. necrophorum on rabbit tissue-culture cells

The effects on rabbit tissue-cultured cells of collagenolytic cell wall component (CCWC) from Fusobacterium necrophorum subsp. necrophorum were investigated. Scanning electron microscopy demonstrated that CCWC damaged the cell surfaces of the rabbit granulocytes and hepatocytes but the effects of the cells differed from each other. Granulocytes appeared smooth and morphologically irregular whereas hepatocytes looked rough and had tiny holes in the cell membranes. Differences in cell viability were observed in MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium, inner salt) assay. The findings suggest that cytotoxic activity in vivo may well contribute to the establishment of an initial injury in visceral tissues, and the action of CCWC could increase the chances of survival for an invading F. necrophorum subsp. necrophorum at the first stages of infection.

Toll-like receptor 2 deficiency delays pneumococcal phagocytosis and impairs oxidative killing by granulocytes

Phagocytosis and killing of Streptococcus pneumoniae was compared in blood-derived wild-type (WT) and Toll-like receptor 2 (TLR2)-deficient (TLR2-/-) polymorphonuclear leukocytes (PMN). Phagocytosis of green fluorescent protein-transformed pneumococci was delayed in TLR2-/- PMN. These cells exhibited also a lower oxidative bactericidal activity against S. pneumoniae than WT PMN, suggesting that TLR2 modulates bacterial clearance in PMN.

Migratory monocytes and granulocytes are major lymphatic carriers ofSalmonellafrom tissue to draining lymph node

Dendritic cells (DC) are recognized as sentinels, which capture antigens in tissue and migrate to the lymph node, where they initiate immune responses. However, when a vaccine strain of green fluorescent protein-expressing Salmonella abortusovis (SAO) was inoculated into sheep oral mucosa, it induced accumulation of myeloid non-DC in the subcapsular sinus and paracortex of the draining lymph node, and SAO was mainly found associated with these cells (granulocytes and macrophages) but rarely with DC. To analyze how bacteria reached lymph nodes, we used cervical pseudo-afferent lymph duct catheterization. We showed that Salmonella administered in the oral mucosa were traveling free in lymph or associated with cells, largely with lymph monocytes and granulocytes but less with DC. SAO also induced a strong influx of these phagocytic cells in afferent lymph. Migrating DC presented a semi-mature phenotype, and SAO administration did not alter their expression of major histocompatibility complex type 2 and coactivation molecules. Compared with blood counterparts, lymph monocytes expressed lower levels of CD40, and granulocytes expressed higher levels of CD80. The data suggest that immunity to bacteria may result from the complex interplay between a mixture of phagocytic cell types, which transport antigens and are massively recruited via lymph to decisional lymph nodes.

CXCR2 blockade influences Anaplasma phagocytophilum propagation but not histopathology in the mouse model of human granulocytic anaplasmosis

Anaplasma phagocytophilum is an obligate intracellular bacterium that infects neutrophils and causes human granulocytic anaplasmosis. Infection induces neutrophil secretion of interleukin-8 or murine homologs and perpetuates infection by recruiting susceptible neutrophils. We hypothesized that antibody blockade of CXCR2 would decrease A. phagocytophilum tissue load by interrupting neutrophil recruitment but would not influence murine hepatic pathology. C3H-scid mice were treated with CXCR2 antiserum or control prior to or on day 14 after infection. Quantitative PCR and immunohistochemistry for A. phagocytophilum were performed and severity of liver histopathology was ranked. Control mice had more infected cells in tissues than the anti-CXCR2-treated group. The histopathological rank was not different between treated and control animals. Infected cells of control mice clustered in tissue more than in treated mice. The results support the hypothesis of bacterial propagation through chemokine induction and confirm that tissue injury is unrelated to A. phagocytophilum tissue load.