Sandra Trevisan Beck

Humoral response to low molecular weight antigens of Mycobacterium tuberculosis by tuberculosis patients and contacts

Much effort has been devoted to the identification of immunologically important antigens of Mycobacterium tuberculosis and to the combination of target antigens to which antibodies from serum of tuberculous patients could react specifically. We searched for IgG antibodies specific for antigens of 45 to 6 kDa obtained after sonication of the well-characterized wild M. tuberculosis strain in order to detect differences in the antibody response to low molecular weight antigens from M. tuberculosis between patients with pulmonary tuberculosis and contacts. Specific IgG antibodies for these antigens were detected by Western blot analysis of 153 serum samples collected from 51 patients with confirmed pulmonary tuberculosis. Three samples were collected from each patient: before therapy, and after 2 and 6 months of treatment. We also analyzed 25 samples obtained from contacts, as well as 30 samples from healthy individuals with known tuberculin status, 50 samples from patients with other lung diseases and 200 samples from healthy blood donors. The positive predictive value for associated IgG reactivity against the 6-kDa and 16-kDa antigens, 6 and 38 kDa, and 16 and 38 kDa was 100% since simultaneous reactivity for these antigens was absent in healthy individuals and individuals with other lung diseases. This association was observed in 67% of the patients, but in only 8% of the contacts. The humoral response against antigens of 16 and 6 kDa seems to be important for the detection of latent tuberculosis since the associated reactivity to these antigens is mainly present in individuals with active disease.

Clinical and epidemiological profile of HIV-infected pregnant women in a service in south Brazil

PURPOSE to analyze the clinical and epidemiological profile, the outcome of pregnancy and the vertical transmission of human immunodeficiency virus (HIV)-infected pregnant women receiving prenatal care at the University Hospital of Santa Maria (HUSM). METHODS A prospective study was conducted on 139 HIV-infected pregnant women attended at the High-Risk Prenatal Care Outpatient Clinic of HUSM, during the period from August 2002 to August 2007, with at least two prenatal visits in this service. Data were collected by an interview and by filling out a research protocol during a prenatal visit. The protocol was attached to the medical records of the patient and kept until the outcome of gestation. Descriptive analysis of quantitative variables was performed using the SPSS software, version 15.0. RESULTS The mean age of the 139 pregnant women studied was 25.6 years (+/-5.8), 79 (56.8%) were white, 81 (58.5%) were married or lived in a stable union, and 90 (65.0%) had less than eight years of schooling. Fifty-one percent of the pregnant women already had two or more children, with a number of children higher than the mean for the state. The infection was diagnosed during the present or a previous pregnancy in more than 70.0% cases. Sexual exposure occurred in 97.0%, and in 59.6% of cases the partner was known to be infected. During the study period, among the cases properly monitored, only one newborn (0.7%) was infected with HIV. CONCLUSIONS Young women in a socioeconomic situation of vulnerability, with low schooling and multiparous represent the majority of HIV-positive pregnant women attended at the service. Evaluations performed during the prenatal period were relevant for the diagnosis of infection in most cases. An early diagnosis associated with proper clinical, obstetrical and psychological monitoring and with nursing care is important to provide appropriate treatment compliance and a reduction of the rates of vertical transmission.

Ciclosporina A e tacrolimus: uma revisão

INTRODUCTION: Therapeutic monitoring of immunosuppressants cyclosporine A (CsA) and tacrolimus (FK506) is indispensable to maintain stable levels of these drugs, avoiding graft rejection in the transplanted patient in the case of low dosage, or toxicity in high dosage, and allowing monitoring of individual treatment. BACKGROUND: In the 80s, the introduction of the potent immunosuppressive drugs CsA and FK506 reduced the incidence of rejection episodes after solid organ transplantation. MECHANISM OF ACTION: CsA and FK506 have distinct chemical structures but similar mechanisms of action, inhibiting the transcription of the first signal for T-lymphocyte activation. TOXICITY: The major side effects associated with CsA and FK506 therapies are nephrotoxicity and neurological disturbances. However, clinical studies demonstrate that FK506 is a potent alternative to CsA due to its lower nephrotoxicity and reversible neurotoxicity when the dosage is decreased. ANALYTICAL METHODOLOGY: For routine monitoring of CsA, the high-performance liquid chromatography with ultraviolet detection (HPLC-UV) was replaced by the radioimmunoassay (RIA) and monoclonal antibody-based fluorescence polarization immunoassay (mFPIA). For the assessment of FK506, it is consensus that highly specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the reference method, although the microparticle enzyme immunoassay (MEIA) and the enzyme-linked immunosorbent assay (ELISA) are currently used for routine monitoring. CONCLUSION: There is a tendency to substitute CsA by FK506 at immunosuppressive regimens, but this is not a consensus yet. The analytical methodology for CsA analysis is well established in the clinical laboratory, but further studies are needed to define the best methodologies for routine FK506 analysis.

Relevância clínica e frequência de padrões citoplasmático e pontilhado fino denso observados em FAN-HEp-2

OBJECTIVES This study aimed to determine the frequency and antibody titers of nuclear dense fine and cytoplasmic patterns with possible clinical correlation. METHODS From 2007 to 2009, the results of 2,788 autoantibody serological tests were assessed by indirect immunofluorescence (IIF) at LAC-HUSM/UFSM, using as substrate HEp-2. RESULTS Among the analyzed samples, 1,998 of them were negative for autoantibodies. Among the positive samples (n = 790), we found 57 (7.2%) showing reactivity pattern described as dense fine speckled (DFS) (3.8%), or cytoplasmic (Cit) fluorescence (3.4%). In samples with standard DFS (n = 29), nine had titers of 1/160, and only one patient had autoimmune disease (AID). Among patients with titers > 1/160, only one patient did not have AID. Among samples with standard Cit (n = 27), 20 had titers of 1/160, and only eight were not associated with AID. The other seven patients with titers > 1/160 reported AID. CONCLUSION The results confirm the value of 1/160 as the best cut-off point for defining AID presence, for any of the fluorescence assessed patterns. However, attention should be given to lower titers, especially for Cit IIF, since only 40% did not report the presence of AID.

Combined use of Western blot/ELISA to improve the serological diagnosis of human tuberculosis

Two recombinant antigens and a crude bacterial antigen of a wild M. tuberculosis strain were used to detect specific IgG antibodies in sera from 52 patients with pulmonary tuberculosis, confirmed by an acid-fast smear and serum culture of these patients and that of 25 contacts. The patients were not infected with HIV. We evaluated the sensitivity and specificity of ELISA, based on the recombinant TbF6 and TbF6/DPEP antigen and a search for reactivity patterns in the Western blot technique, using whole mycobacterium antigen. Serum samples from 22 healthy individuals and from 30 patients with lung diseases other than tuberculosis were used as controls. The best ELISA results were obtained with the TbF6/DPEP antigen combination, which gave 85% sensitivity and 91% specificity. ELISA sensitivity improved from 85% to 92% when the Western blot results were used. Western blot specificity was 100% when antibody reactivity with different antigenic bands was analyzed and associated. The association of TbF6/DPEP antigens used in ELISA with specific patterns of reactivity determined by Western blot can help make an identification when classic methods for the diagnosis of pulmonary tuberculosis are not sufficient.

A study of iga antibody response to different mycobacterium tuberculosis antigens in the diagnosis and monitoring of pulmonary tuberculosis

We evaluated the performance of the ELISA technique in the detection of IgA antibodies against different Mycobacterium tuberculosis antigenic preparations in serum samples from 49 patients with pulmonary tuberculosis collected before and after the start of specific treatment. The controls consisted of serum samples from healthy patients without any prior contact with the bacteria and serum samples from patients with other pneumopathies. Glycolipid antigen gave the best diagnostic performance, with a sensitivity of 88% and specificities varying from 88 to 100% in the control groups. These antigens constitute a powerful tool for the diagnosis and monitoring of patients with pulmonary tuberculosis.

Taxa de probabilidade como guia de interpretação do FAN-HEp-2 na pesquisa de autoanticorpos no lúpus eritematoso sistêmico

BACKGROUND: The magnitude of variation in pre-test probability of a certain disease to a new post-test probability may be determined through likelihood ratio (LR), which reflects the clinical value of the result obtained in the procedure. OBJECTIVES: To verify the clinical impact of autoantibody screening on the diagnosis of Systemic Lupus Erythematosus (SLE) and other autoimmune diseases through LR measurement when HEp-2 cells are used for screening or investigation into anti-Ds-DNA antibody, showing the importance of parameters such as sensitivity and specificity. MATERIAL AND METHOD: Autoantibodies were studied by indirect immunofluorescence using HEp-2 cells and Crithidia luciliae anti-DNA test in serum samples collected from 47 individuals diagnosed with SLE, 27 with other autoimmune diseases and 71 with other pathologies. RESULTS: The presence of reactivity > 1/160 in HEp-2 cells showed positive LR with significant impact on post-test probability even in the absence of complementary investigation. In serum samples with reactivity < 1/160, anti-dsDNA screening has great relevance to the diagnosis of SLE with a great impact on post-test probability. DISCUSSION: As to sensibility and specificity of FAN test for results grouped into different intervals, it was confirmed that results with low titer do not change post test probability of disease occurrence. Complementary tests with high specificity have major clinical value. Both the investigation of parameters such as sensibility /specificity and likelihood ratio of diagnostic tests have crucial importance in efficient clinical evaluation.

Association of HLA antigens and BCR-ABL transcripts in leukemia patients with the Philadelphia chromosome

Objective This study aimed to verify the association between human leukocyte antigens and the bcr-abl fusion protein resulting from t(9;22)(q34;q11) in chronic leukemia myeloid and acute lymphoblastic leukemia patients. Methods Forty-seven bcr-abl positive individuals were evaluated. Typing was performed bymicrolymphocytotoxicity and molecular biological methods (human leukocyte antigens Class I and Class II). A control group was obtained from the data of potential bone marrow donors registered in the Brazilian Bone Marrow Donor Registry (REDOME). Results Positive associations with HLA-A25 and HLA-B18 were found for the b2a2 transcript, as well as a tendency towards a positive association with HLA-B40 and a negative association with HLA-A68. The b3a2 transcript showed positive associations with HLA-B40 and HLA-DRB1*3. Conclusion The negative association between human leukocyte antigens and the BCR-ABL transcript suggests that binding and presentation of peptides derived from the chimeric protein are effective to increase a cytotoxic T lymphocyte response appropriate for the destruction of leukemic cells.

IMPORTÂNCIA DO RASTREAMENTO SOROLÓGICO DA TOXOPLASMOSE EM GESTANTES ATENDIDAS EM AMBULATÓRIO DE PRÉ-NATAL DE ALTO RISCO

Estudo transversal, retrospectivo, de 408 gestantes imunocompetentes, atendidas em Ambulatorio de Pre-Natal de Alto Risco, entre janeiro de 2005 a dezembro de 2006 para verificar a relevância da triagem sorologica da infeccao por Toxoplasma gondii, nesta populacao. Foram analisados os perfis sorologicos, para pesquisa de anticorpos especificos IgM, IgG e avidez de IgG, atraves de metodos imunologicos ELFA® e MEIA®. Foram identificadas, 271 (66,42) imunes, 121 (29,6%) suscetiveis, seis (1,47%) com provavel doenca aguda e 10 (2,45%) casos com teste da avidez de IgG foi realizado apos o quarto mes de gestacao, alem do tempo estabelecido como ideal para pesquisa deste parâmetro laboratorial. A realizacao do teste de avidez de IgG, em tempo adequado, permitiu definir um maior numero de casos passiveis de tratamento. O encontro de 29,6% de gestantes suscetiveis a infeccao por T. gondii mostrou a importância da triagem sorologica na prevencao de casos de toxoplasmose aguda . Palavras-chave: toxoplasmose; gestantes; IgG; IgM; cuidado pre-natal Transversal retrospective study of serological test to T. gondii infection for 408 immunocompetent pregnant women attended in The High Risk Prenatal Ambulatory, among January, 2005 to December, 2006 to determinate the importance of screening for Toxoplasma gondii ( T. gondii ) infection in this population. Serological profile for specific IgM, IgG and IgG avidity done by ELFA® e MEIA® methodology were analyzed. There were found 271(66,42%) out of 408 pregnant women immune to T.gondii infection, 41 (29,3%) susceptible, six (1,47%) with probable acute disease and ten (2,45%) with avidity test realized after the adequate period established like optimal for research. The accomplishment of the IgG avidity test during the correct time allows the detection of a higher number of acute diseases. The data for 29,6% of pregnant women susceptible to infection by T. gondii shows the importance of serological screening for toxoplasmosis in order to prevent cases of acute toxoplasmosis in the population studied. Keywords: Toxoplasmosis, Pregnant, IgG, IgM, Prenatal Care.

ANTICORPOS DE REAÇÃO CRUZADA DURANTE INFECÇÃO AGUDA POR T. GONDII

Agentes como Toxoplasma Gondii,Citomegalovirus (CMV) e virus da imunodeficiencia humana (HIV) podem causar a Sindrome da Mononucleose Infecciosa, por apresentar expressao clinica e laboratorial muito semelhante a mononucleose infecciosa classica, provocada pelo virus Epstein-Barr(EB). O grau desta semelhanca e muito variavel, podendo predominar o aspecto clinico ou o laboratorial, e ser mais ou menos intensa. O diagnostico laboratorial e dificultado pela possibilidade de reacao cruzada de anticorpos IgM entres estes patogenos. No presente estudo, foram analisadas as caracteristicas clinicas e laboratoriais de um paciente com diagnostico de Toxoplasmose, onde ocorreram reacoes falso-positivas em exames sorologicos para HIV e Citomegalovirus.