Specific serodiagnosis of visceral leishmaniasis using a Leishmania donovani antigen identified by expression cloning

A λgt11 expression library was constructed using mRNA from the promastigote form of Leishmania donovani (African isolate MHOM/ET/67/HU3). The library was screened with serum obtained from a patient who contracted visceral leishmaniasis in the Sudan. Several cDNA clones which expressed β-galactosidase/L. donovani antigen fusion proteins were isolated. One of these clones corresponded to a 60 kDa membrane-associated antigen. By a Western blot assay antibodies against the fusion protein were detected universally in the sera of visceral leishmaniasis patients. They were not detected in sera from patients with cutaneous leishmaniasis or other parasitic protozoan infections. The gene coding for this antigen was specific to the genus Leishmania as judged by DNA hybridisation, and its chromosomal location was conserved. A 20 kb mRNA was detected on Northern blots of promastigote RNA.     

Immuno stimulating glycophosphosphingolipid antigen from Leishmania donovani is recognized by visceral leishmaniasis patient sera

Surface antigens on Leishmania promastigotes and infected macrophages are obvious targets in immunoprophylaxis for leishmanial infection. The glycophosphosphingolipid (GSPL) antigen isolated from Leishmania donovani surface membrane was recognized by sera from patients with visceral leishmaniasis. GSPL was also expressed on the membrane of parasite-infected macrophages. The effect of GSPL on the production of reactive oxygen species (ROS) and reactive nitrogen intermediates (RNI) was studied using the macrophage cell line J774.1. In addition, induction of IFNγ, IL4, IL10, IL12 secretion in presence of GSPL was investigated in PBMC from normal individuals. ROS and RNI in addition to IFNγ and IL12 were induced by GSPL. Though there was a moderate induction of IL10, there was very little induction of the Th2 cytokine IL4. GSPL also induced blood cells to proliferate. The data suggests that this functionally important antigen of L. donovani may be used as a candidate vaccine.     

Elevated levels of soluble non-classical major histocompatibility class I molecule human leucocyte antigen (HLA)-G in the blood of HIV-infected patients with or without visceral leishmaniasis

The non-classical class I major histocompatibility complex molecules human leucocyte antigen (HLA)-G have been shown to play a role in HIV persistence, but no data are available on the expression of the soluble forms HLA-G5 and sHLA-G1 in HIV-infected patients with and without opportunistic infections. The soluble HLA-G isoform was measured with an enzyme-linked immunosorbent assay (ELISA) method in plasma from 94 subjects: 31 HIV-1-seropositive, 17 with visceral leishmaniasis (VL), seven with both VL and HIV-1 infection and 39 healthy HIV-seronegative subjects. Between groups, the frequency of sHLA-G positivity was statistically different: 81% of HIV-infected patients were positive, as were 57% of HIV-Leishmania infantum co-infected patients, 35% of HIV-seronegative patients with VL and 3% of healthy controls. Levels of the soluble forms of the immunomodulatory molecules HLA-G are elevated during HIV infection. In HIV-Leishmania co-infected patients, sHLA-G secretion could contribute to the tolerogenic environment and to Leishmania immune evasion.     

Immune induction by adjuvanted Leishmania donovani vaccines against the visceral leishmaniasis in BALB/c mice

Visceral leishmaniasis (VL) is a neglected tropical disease caused by Leishmania donovani or Leishmania infantum. Currently, the patients are treated with chemotherapeutic drugs; however, their toxicity limits their use. It would be desirable to develop a vaccine against this infection. In this study, we assessed the efficacy of different vaccine formulations at variable time points. Heat-killed (HK) antigen of Leishmania donovani was adjuvanted with two adjuvants (AddaVax and Montanide ISA 201) and three immunizations at a gap of 2 weeks (wk) were given to BALB/c mice. After 2 weeks of the last booster, mice were given challenge infection and sacrificed before challenge and after 4wk, 8wk, and 12 wk post-challenge. Significant protective immunity was observed in all the immunized animals and it was indicated by the notable rise in delayed-type hypersensitivity (DTH) response, remarkably declined parasite burden, a significant increase in the levels of interferon-gamma (IFN-γ), interleukin-12, interleukin-17 (Th1 cytokines), and IgG2a in contrast to infected control mice. Montanide ISA 201 with HK antigen provided maximum protection followed by AddaVax with HK and then HK alone. These findings elaborate on the importance of the tested adjuvants in the vaccine formulations against murine visceral leishmaniasis.     

T cell suppression in the bone marrow of visceral leishmaniasis patients: impact of parasite load

Visceral leishmaniasis (VL) is a disseminated and lethal disease of reticulo‐endothelial system caused by protozoan parasites Leishmania donovani and L. infantum, which are known to induce host T cell suppression. To understand the impact of parasite load on T cell function, the present was focused on parasite load with T cell function in bone marrow of 26 VL patients. We observed significant enrichment of forkhead box protein 3 (FoxP3)⁺ (P = 0·0003) and interleukin (IL)‐10⁺ FoxP3⁺ regulatory T cells (T_reg) (P = 0·004) in the bone marrow (BM) of patients with high parasite load (HPL) compared with low parasite load (LPL). Concordantly, T effector cells producing interferon (IFN)‐γ (P = 0·005) and IL‐17A (P = 0·002) were reduced in the BM of HPL. Blocking of T_reg‐cell derived suppressive cytokines [(IL‐10 and transforming growth factor (TGF)‐β] rescued the effector T cells and their functions. However, it was observed that TGF‐β levels were dominant, favouring T_reg cell differentiation. Furthermore, the low ratio of IL‐6/TGF‐β favours the suppressive milieu in HPL patients. Here we show the change in levels of various cytokines with the parasitic load during active VL, which could be helpful in devising newer immunotherapeutic strategies against this disease.     

Role of fine‐needle aspiration cytology in the prompt diagnosis of recurrence of visceral leishmaniasis presented as isolated cervical leishmanial lymphadenopathy

We report a case of isolated cervical leishmanial lymphadenopathy diagnosed by fine‐needle aspiration cytology (FNAC) in apparently cured case of visceral leishmaniasis. A 28‐year‐old female presented with cervical lymphnode enlargement to surgery outpatient department and was subjected for FNAC. Smear showed numerous Leishmania donovani bodies in the cytoplasm of macrophages and giant cells, and extracellular spaces. She was treated by Amphotericin B for alternate 14 days and the size of the lymphnode regressed. She was found asymptomatic for 1 year of follow‐up. Diagn. Cytopathol. 2013. © 2011 Wiley Periodicals, Inc     

抗杜氏利什曼原虫犬分离株单克隆抗体的研制及用于病犬血清循环抗原的检测

本文报道用杜氏利什曼原虫大分离株前鞭毛体膜抗原免疫BALB/c小鼠的脾细胞与Sp2/0瘤细胞融合,得到多株分泌抗体较高且稳定的细胞株。进一步筛选出McAb C11-G10-A4可用于检测病犬血清循环抗原。用McAb-AST检测采自甘肃省黑热病流行区的30份犬血清,阳性率30％。与骨髓涂片查病原体的总符合率为86.7％,阳性符合率达100％。69份非流行区对照大血清检测结果,仅1份出现阳性反应,可见本试验的敏感性较高,特异性较强(98.55％)。     

The role of complement in the acute inflammatory process in the skin and in host–parasite interaction in hamsters inoculated with Leishmania (Leishmania) chagasi

Tecidual reaction at the inoculation site of L. (L.)chagasi promastigotes in hamsters depleted and non-depleted of complement was studied within 2, 6, 12, 24, 48 and 72 hours of infection. The inflammatory reaction was characterized by early predominance of polymorphonuclear cells (PMN) at 2, 6 and 12 hours of infection, mixed infiltrate of PMN and mononuclear cells (MN) at 24 hours, followed by predominance of MN at 48 and 72 hours after infection. The group depleted of complement showed a higher number of PMN at 2 hours and lower numbers of MN at 72 hours after infection ( P <0.0001). In the depleted group the phagocytosis by PMN was lower at 2 and 24 hours and by MN was lower at 24, 48 and 72 hours after infection. Electron microscopy showed extracellular intact and degenerated parasites, and lysed intracellular parasites, in PMN; and, rarely, preserved intracellular parasites in MN at 2, 6 and 12 hours after infection. The groups examined at 24, 48 and 72 hours of infection showed only cellular and parasite debris in mononuclear inflammatory cells. C₃b deposits were detected by immunofluorescence in the interstitium and in the cytoplasm of inflammatory cells in non-depleted group at 2, 6 and 12 hours of infection. No immunoglobulin was detected in either group. Visceralization was detected 240 days after infection. The complement system has an important role in the inflammatory reaction and phagocytosis. The ultrastructural findings showed that the escape of the parasite probably occurs soon after inoculation.     

Hepatic extracellular matrix alterations in dogs naturally infected with Leishmania (Leishmania) chagasi

The aim of this work was to study alterations in the extracellular matrix of liver in dogs naturally infected with Leishmania ( Leishmania ) chagasi that are correlated with clinical aspects and with histological, parasitological and immunological findings. The study was carried out on 30 dogs, 10 uninfected (control group) and 20 infected. The infected animals were further divided into two groups: an asymptomatic group of 10 dogs without clinical signs of the disease; and a symptomatic group of 10 dogs with classical clinical signs. All thirty animals were mongrel dogs of undefined age, obtained from the municipality of Belo Horizonte, MG, metropolitan area. During necropsy, liver fragments were collected and fixed in 10% buffered formaldehyde for histological examination. Paraffined sections of the tissues were stained with haematoxylin–eosin, Gomori's ammoniacal silver stain for reticular fibres and strepto-avidin peroxidase for immunohistochemical detection of Leishmania amastigotes. Frozen tissue sections were stained by immunofluorescence for fibronectin (FN) and laminin (LN). Liver collagen deposition was significantly greater in the infected than the control animals and differed significantly between the symptomatic and asymptomatic dogs. There was a positive correlation between the parasite load and liver collagen deposition. The increased collagen deposition in infected animal livers may be associated with the parasite burden. Adhesive FN and LN fibres were significantly more highly expressed in the livers of symptomatic than of asymptomatic dogs. Our results demonstrate that canine visceral leishmaniasis causes fibrogenesis in liver, associated with the parasite load and degenerative processes.     

In vitro activity and in vivo efficacy of a combination therapy of diminazene and chloroquine against murine visceral leishmaniasis

The present study evaluated the in vitro activity and in vivo efficacy of diminazene combined with chloroquine as a potential drug against Leishmania donovani.Amphotericin B was used as a positive control drug.In vitro activity involved incubation of various drug concentrations with promastigotes or vero cells in culture before determination of parasite growth inhibition or cell death while in vivo evaluations involved infection of various mice groups with virulent L.donovani parasites and treatment with test drug compounds following disease establishment.Weight changes in experimental mice were also evaluated before infection and throughout the experiment.The results indicated that the diminazene-chloroquine combination was at least nine times more efficacious than individual drugs in killing promastigotes in culture.The diminazene-chloroquine combination was safer(Ld₅₀=0.03±0.04) than Amphotericin B(Ld₅₀=0.02±0.01).Body weight in infected mice increased significantly（P=0.0007） from day7 to day 37 following infection（P=0.026）.However,body weight remained comparable in all mice groups during treatment（P=0.16）.The diminazene-chloroquine combination significantly reduced splenic parasite numbers as compared to individual drug therapies（P=0.0001） although Amphotericin B was still more efficacious than any other treatment（P=0.0001）.Amongst the test compounds,the diminazene-chloroquine combination showed the lowest level of IgG antibody responses with results indicating significant negative correlation between antileishmanial antibody responses and protection against disease.These findings demonstrate the positive advantage and the potential use of a combined therapy of diminazene-chloroquine over the constituent drugs.Further evaluation is recommended to determine the most efficacious combination ratio of the two compounds.     

Natural autoantibodies, IgG antibodies to tetanus toxoid and CD5+ B cells in patients with Mediterranean visceral leishmaniasis. The Leishmania Study Group.

Natural autoantibodies (NaAb) and IgG antibodies to tetanus toxoid (TT) were analysed in the sera of 38 children with active visceral leishmaniasis (VL) previously vaccinated with TT and in 30 healthy controls matched for sex and age. Patients exhibited high levels of NaAb to a panel of self antigens (tubulin, myosin, myoglobin, actin) contrasting to a low level of IgG to TT. Analysis of the circulating B cells in 26 untreated patients showed a low percentage of CD5+ per total B cells (3-66%, mean 36.6%) compared with 14 normal controls (17.8-66.6%, mean 52.7%) (P < 0.001). Evaluation of these parameters after antimonial therapy showed a significant decrease of the level of the NaAb (P < 0.0005), and a spontaneous increase of the level of the IgG to TT without any vaccine boosting (P < 0.01). In contrast, there was a significant increase in CD5+ B cells (P < 0.0005). This result suggests that CD5+ B cells may be sequestrated in parasitized lymphoid organs and may be released after remission. These findings show that the polyclonal B cell activation that occurs during active VL involves mainly B cells bearing NaAb and are in favour of a functional dichotomy of B cells.     

Exacerbation of Leishmania (Viannia) shawi infection in BALB/c mice after immunization with soluble antigen from amastigote forms

The present study aimed to evaluate the effects of immunization with soluble amastigote (AmaAg) and promastigote (ProAg) antigens from Leishmania (Viannia) shawi on the course of infection in BALB/c mice. After immunization with AmaAg, the challenged group showed greater lesion size and parasite load in the skin and lymph nodes, associated with diminished interleukin (IL)-2, IL-4, IL-10, interferon (IFN)-γ and nitrate levels in the supernatant of lymph node cell cultures, together with increases in transforming growth factor (TGF)-β concentrations and humoral immune response. In contrast, immunization with ProAg led to smaller lesion size with reduced numbers of viable parasites in the skin. Protection was associated with increases in IL-12, IFN-γ, TGF-β and nitrates and decreases in IL-4 and IL-10 levels. Concerning humoral immune response, a significant reduction in anti-leishmania immunoglobulin G was verified in the ProAg-challenged group. Analysis of these results suggests that AmaAg induced a suppressive cellular immune response in mice, favouring the spread of infection, whereas ProAg induced partial protection associated with increased cellular immune response.     

Leishmania donovani and Pneumocystis jirovecii (carinii) diagnosed on bronchoalveolar lavage cytology in a liver transplant recipient with Cytomegalovirus infection

Liver transplant recipients are prone to several infections, including lung infections, which can lead to substantial morbidity and mortality. Bronchoalveolar lavage (BAL) cytology is a rapid and sensitive diagnostic tool to identify the etiologic agents. We report a rare case of a 24‐year‐old male, post Live donor liver transplantation for autoimmune chronic liver disease, who presented with cough, fever, weight loss, and cavitatory lesion in lung. BAL cytology revealed Leishmania donovani (LD) and Pneumocystis jirovecii/carinii (PCP). Cytomegalovirus deoxyribonucleic acid polymerase chain reaction (CMV DNA PCR) test showed markedly raised levels. Patient was put on treatment for these multiple infections and showed significant improvement. Thus, rapid diagnosis of infections through BAL cytology is crucial in transplant recipients to institute timely therapy and avoid undesirable empirical treatments. Moreover, this case highlights a rare finding of LD bodies along with PCP in BAL cytology.     

Immunization with Leishmania donovani protein disulfide isomerase DNA construct induces Th1 and Th17 dependent immune response and protection against experimental visceral leishmaniasis in Balb/c mice

In the present study, the efficacy of Leishmania donovani protein disulfide isomerase (LdPDI) as a DNA vaccine was evaluated in BALB/C mice. Mice immunized with the LdPDI-DNA construct were found to be the most immuno-reactive, as the construct induced higher T-cell proliferation. The increased T-cell proliferation was associated with a substantial rise in Th1 and Th17+ CD4 cell response and triggered a higher proportion of CD8+ T cells for the release of interferon-gamma along with a reduced splenic parasite load on Days20 and 60 post challenge (PC). Furthermore, the vaccine construct triggered increased interferon (IFN)-γ, interleukin(IL)-17A, and IL-22 release accompanied by decreased extracellular signal-regulated kinases (ERK) 1/2 signaling and increased mitogen-activated protein kinase (MAPK) signaling coinciding with an increase in the amount of nitrite and reactive oxygen species (ROS)in vaccinating the splenocyts. We summarize from our data that the PDI-DNA construct of Leishmania donovani has the potential to elicit protective immunity through the pro-inflammatory cytokines of CD8+ and CD4+(Th1 and Th17) following an intervention in the downstream signaling event of ERK1/2 (probably through p38MAPK signaling). Therefore, the study suggests a new control against visceral leishmaniasis in the future.     

Early in vitro priming of distinct T(h) cell subsets determines polarized growth of visceralizing Leishmania in macrophages

An in vitro priming system of murine naive splenocytes was established to investigate early immune responses to LEISHMANIA: chagasi, the agent of visceral leishmaniasis in the New World. Priming of splenocytes from resistant C3H and CBA or susceptible BALB and B10 mice with L. chagasi resulted in blast transformation and in proliferating parasite-specific CD4(+) T cells secreting a differential complement of cytokines (IFN-gamma and low IL-10 levels for resistant T cells; IFN-gamma, IL-4 and high IL-10 levels for susceptible T cells). After priming, intracellular parasite load was much higher in susceptible than in resistant-type splenocyte cultures. On the other hand, infection of purified splenic macrophages from either resistant or susceptible mice with live L. chagasi promastigotes, resulted in comparable parasite loads. Moreover, when early CD4(+) T cell priming in splenocyte cultures was disrupted with anti-CD4 mAb, polarized parasite growth was abolished, becoming comparable in resistant and susceptible cultures. Neutralizing IL-4 activity during splenocyte priming did not affect the final parasite load in susceptible cultures. However, neutralizing IL-10 activity markedly decreased parasite load in susceptible, but not in resistant splenic macrophages. These results suggest that IL-10 plays an important role in L. chagasi infection in susceptible hosts. The results also indicate that innate control of growth of a visceralizing LEISHMANIA: in splenic macrophages results from the ability to activate different CD4(+) T cell subsets.     

Complete protection against experimental visceral leishmaniasis with complete soluble antigen from attenuated Leishmania donovani promastigotes involves Th1‐immunity and down‐regulation of IL‐10

Compared with cutaneous leishmaniasis, vaccination against visceral leishmaniasis has received limited attention. Most available drugs are toxic, and relapse after cure remains a chronic problem. Growing limitations in available chemotherapeutic strategies due to emerging resistant strains and lack of an effective vaccine strategy against visceral leishmaniasis deepens the crisis. Complete soluble antigen (CSA), from a β1‐4 galactosyltransferase expressing attenuated Leishmania donovani parasite, induced protection against subsequent challenge and during active infections. CSA immunization was effective against both pentavalent antimony sensitive and resistant strains of L. donovani. Majority (～85%) of the immunized animals showed sterile protection. Resolution of the disease required the presence of T cells, and the recovered animals remained immune to re‐challenge. Control of the parasites was dependent on type 1 CD4⁺ helper cells, which evolved in the presence of IL‐12 and activated macrophages through the production of IFN‐γ. Immunity was adoptively transferable and was dependent on both CD4⁺ and CD8⁺ cells. CSA immunization led to enhanced IFN‐γ production, while suppressing the IL‐10 production. However, CSA immunization did not abrogate IL‐4 production. Our results accentuate the need to establish a favorable cellular immunity while intervening with the development of Th2 cells during leishmania infection.     

Association of CD8+ T cell infiltration in oesophageal carcinoma lesions with human leucocyte antigen (HLA) class I antigen expression and survival

Oesophageal cancer is one of the most aggressive tumours with a poor prognosis. However, little is known about the immune response in the tumour microenvironment. To investigate the role of immunosurveillance in the clinical course of oesophageal squamous cell carcinoma, 98 formalin-fixed, paraffin-embedded primary tumours were analysed using immunohistochemical methods for human leucocyte antigen (HLA) class I heavy chain and β2-microglobulin expression and for CD4-, CD8- and CD57-positive cell infiltration. HLA class I expression of tumour cells was correlated positively with infiltration of CD8(+) T cells into the cancer nest, but not with the clinical course of disease. However, CD8(+) and CD4(+) T cell infiltration was correlated with prognosis. These results suggest that tumour antigen-specific cellular immune response plays a role in the clinical course of the disease and that HLA class I antigen expressed on tumour cells contribute to this association most probably by mediating the interactions between tumour cells and CD8(+) T cells.     

Expression of HLA class I antigens in transporter associated with antigen processing (TAP)-deficient mutant cell lines

Abstract: Cells lacking expression of the transporter associated with antigen processing (TAP) are deficient in surface HLA class I, yet express reduced levels of HLA-A2 antigen through TAP-independent processing pathways. We have analysed the expression of HLA-A, -B and -C antigens on the 721.174 and T2 TAP-deficient mutant cell lines using a panel of monoclonal antibodies specific for the HLA antigens encoded by the genotype of these cells. Our study has shown the constitutive expression of HLA-Cwl molecules on the cell surface of both T2 and 721.174 cells and has confirmed that HLA-A2 and HLA-B51 are expressed at low levels. Transfection of 721.174 cells with cDNAs encoding TAP1 and TAP2 proteins did not fully restore HLA class I antigen expression on these cells, which appeared to be mainly due to a deficiency in expression of the HLA-B51-associ-ated Bw4 epitope. This suggests that additional antigen-processing genes may be required for optimal generation of HLA-B-binding peptides. Our results indicate that TAP-independent pathways of antigen-processing provide peptides for functional expression of all three classical HLA class I molecules.