Decay accelerating factor (DAF) as the host antigen with protective activity to complement killing of schistosomula

The acquisition of host antigens by Schistosoma mansoni was studied by evaluating the resistance of schistosomula to the complement attack mediated by lethal antibody. Schistosomula cultured for 24 hours with intact human erythrocytes (N-HuE) or ghosts of any type of ABO or Rh blood group, showed a marked resistance to complement damage. Sheep red blood cells, pronase-treated N-HuE or erythrocytes from patients with paroxysmal nocturnal hemoglobinuria, which are complement-sensitive cells, were unable to protect schistosomula. Schistosomula protected by N-HuE became again susceptible to complement killing after incubation with a monoclonal antibody anti-DAF. These results indicate that, in vitro, host DAF from N-HuE can be acquired by schistosomula surface in a biological active form that protects the parasite from the complement lesion.

The use of mannan antigen and anti-mannan antibodies in the diagnosis of invasive candidiasis: recommendations from the Third European Conference on Infections in Leukemia.

INTRODUCTION: Timely diagnosis of invasive candidiasis (IC) remains difficult as the clinical presentation is not specific and blood cultures lack sensitivity and need a long incubation time. Thus, non-culture-based methods for diagnosing IC have been developed. Mannan antigen (Mn) and anti-mannan antibodies (A-Mn) are present in patients with IC. On behalf of the Third European Conference on Infections in Leukemia, the performance of these tests was analysed and reviewed. METHODS: The literature was searched for studies using the commercially available sandwich enzyme-linked immunosorbent assays (Platelia™, Bio-Rad Laboratories, Marnes-la-Coquette, France) for detecting Mn and A-Mn in serum. The target condition of this review was IC defined according to 2008 European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. Sensitivity, specificity and diagnostic odds ratios (DOR) were calculated for Mn, A-Mn and combined Mn/A-Mn testing. RESULTS: Overall, 14 studies that comprised 453 patients and 767 controls were reviewed. The patient populations included in the studies were mainly haematological and cancer cases in seven studies and mainly intensive care unit and surgery cases in the other seven studies. All studies but one were retrospective in design. Mn sensitivity was 58% (95% confidence interval [CI], 53-62); specificity, 93% (95% CI, 91-94) and DOR, 18 (95% CI 12-28). A-Mn sensitivity was 59% (95% CI, 54-65); specificity, 83% (95% CI, 79-97) and DOR, 12 (95% CI 7-21). Combined Mn/A-Mn sensitivity was 83% (95% CI, 79-87); specificity, 86% (95% CI, 82-90) and DOR, 58 (95% CI 27-122). Significant heterogeneity of the studies was detected. The sensitivity of both Mn and A-Mn varied for different Candida species, and it was the highest for C. albicans, followed by C. glabrata and C. tropicalis. In 73% of 45 patients with candidemia, at least one of the serological tests was positive before the culture results, with mean time advantage being 6 days for Mn and 7 days for A-Mn. In 21 patients with hepatosplenic IC, 18 (86%) had Mn or A-Mn positive test results at a median of 16 days before radiological detection of liver or spleen lesions. CONCLUSIONS: Mn and A-Mn are useful for diagnosis of IC. The performance of combined Mn/A-Mn testing is superior to either Mn or A-Mn testing.

Immuno-reactive proteins from Mycobacterium immunogenum useful for serodiagnosis of metalworking fluid hypersensitivity pneumonitis.

Metalworking fluid-associated hypersensitivity pneumonitis (MWF-HP) is a pulmonary disease caused by inhaling microorganisms present in the metalworking fluids used in the industrial sector. Mycobacterium immunogenum is the main etiological agent. Among the clinical, radiological and biological tools used for diagnosis, serological tests are important. The aim of this study was to identify immunogenic proteins in M. immunogenum and to use recombinant antigens for serological diagnosis of MWF-HP. Immunogenic proteins were detected by two-dimensional Western blot and candidate proteins were identified by mass spectrometry. Recombinant antigens were expressed in Escherichia coli and tested by enzyme-linked immunosorbent assay (ELISA) with the sera of 14 subjects with MWF-HP and 12 asymptomatic controls exposed to M. immunogenum. From the 350 spots visualized by two-dimensional gel electrophoresis with M. immunogenum extract, 6 immunogenic proteins were selected to be expressed as recombinant antigens. Acyl-CoA dehydrogenase antigen allowed for the best discrimination of MWF-HP cases against controls with an area under the receiver operating characteristics (ROC) curve of 0.930 (95% CI=0.820-1), a sensitivity of 100% and a specificity of 83% for the optimum threshold. Other recombinant antigens correspond to acyl-CoA dehydrogenase FadE, cytosol aminopeptidase, dihydrolipoyl dehydrogenase, serine hydroxymethyltransferase and superoxide dismutase. This is the first time that recombinant antigens have been used for the serodiagnosis of hypersensitivity pneumonitis. The availability of recombinant antigens makes it possible to develop standardized serological tests which in turn could simplify diagnosis, thus making it less invasive.

Paper dels exosomes en la comunicació entre cèl•lules presentadores d'antigen

Projecte de recerca elaborat a partir d’una estada al Institut Gustave-Roussy, França, entre febrer i març del 2007. L'objectiu principal del projecte consisteix en estudiar la interacció dels exosomes , obtinguts a partir d'un model in vitro com són les cél•lules dendrítiques derivades de monòcits, amb els subtipus de cel•lules dendrítiques mieloides i plasmacitoides, valorant la seva capacitat de captació i evaluant els canvis fenotípics i funcionals per part de les cèl•lules diana.

Simultaneous CD8+ T cell responses to multiple tumor antigen epitopes in a multipeptide melanoma vaccine.

The recent identification and molecular characterization of tumor-associated antigens recognized by tumor-reactive CD8+ T lymphocytes has led to the development of antigen-specific immunotherapy of cancer. Among other approaches, clinical studies have been initiated to assess the in vivo immunogenicity of tumor antigen-derived peptides in cancer patients. In this study, we have analyzed the CD8+ T cell response of an ocular melanoma patient to a vaccine composed of four different tumor antigen-derived peptides administered simultaneously in incomplete Freund's adjuvant (IFA). Peptide NY-ESO-1(157-165) was remarkably immunogenic and induced a CD8+ T cell response detectable ex vivo at an early time point of the vaccination protocol. A CD8+ T cell response to the peptide analog Melan-A(26-35 A27L) was also detectable ex vivo at a later time point, whereas CD8+ T cells specific for peptide tyrosinase(368-376) were detected only after in vitro peptide stimulation. No detectable CD8+ T cell response to peptide gp100(457-466) was observed. Vaccine-induced CD8+ T cell responses declined rapidly after the initial response but increased again after further peptide injections. In addition, tumor antigen-specific CD8+ T cells were isolated from a vaccine injection site biopsy sample. Importantly, vaccine-induced CD8+ T cells specifically lysed tumor cells expressing the corresponding antigen. Together, these data demonstrate that simultaneous immunization with multiple tumor antigen-derived peptides can result in the elicitation of multiepitope-directed CD8+ T cell responses that are reactive against antigen-expressing tumors and able to infiltrate antigen-containing peripheral sites.

Fine structural variations of alphabetaTCRs selected by vaccination with natural versus altered self-antigen in melanoma patients.

Immunotherapy of cancer is often performed with altered "analog" peptide Ags optimized for HLA class I binding, resulting in enhanced immunogenicity, but the induced T cell responses require further evaluation. Recently, we demonstrated fine specificity differences and enhanced recognition of naturally presented Ag by T cells after vaccination with natural Melan-A/MART-1 peptide, as compared with analog peptide. In this study, we compared the TCR primary structures of 1489 HLA-A*0201/Melan-A(26-35)-specific CD8 T cells derived from both cohorts of patients. Although a strong preference for TRAV12-2 segment usage was present in nearly all patients, usage of particular TRAJ gene segments and CDR3alpha composition differed slightly after vaccination with natural vs analog peptide. Moreover, TCR beta-chain repertoires were broader after natural than analog peptide vaccination. In all patients, we observed a marked conservation of the CDR3beta amino acid composition with recurrent sequences centered on a glycyl-leucyl/valyl/alanyl-glycyl motif. In contrast to viral-specific TCR repertoires, such "public" motifs were primarily expressed by nondominant T cell clonotypes, which contrasted with "private" CDR3beta signatures frequently found in T cell clonotypes that dominated repertoires of individual patients. Interestingly, no differences in functional avidity were observed between public and private T cell clonotypes. Collectively, our data indicate that T cell repertoires generated against natural or analog Melan-A peptide exhibited slightly distinct but otherwise overlapping and structurally conserved TCR features, suggesting that the differences in binding affinity/avidity of TCRs toward pMHC observed in the two cohorts of patients are caused by subtle structural TCR variations.

IgM immunoglobulins reacting with the phenolic glycolipid-1 antigen from Mycobacterium leprae in sera of leprosy patients and their contacts

For the first time in Brazil it was investigated the occurrence of IgM anti-PGL-1 in the sera of household contacts of leprozy patients using the ELISA methodology. The sera of the multipatients. It was observed a high subclinical infection incidence among household contacts (19.4%). The percentage of leprosy development was 5% (1/21) among the seropositive contact group. This finding suggests that serology could be useful as prognostic test, but for better definition is necessary to tet a population from endemic area for long period time.