Pesquisa de IgA contra o antígeno recombinante HspX de Mycobacterium tuberculosis no diagnóstico de tuberculose pleural / Determination of levels of specific IgA to the HspX recombinant antigen of Mycobacterium tuberculosis for the diagnosis of pleural tuberculosis

OBJETIVO: Avaliar a acurácia da dosagem de IgA contra o antígeno recombinante HspX no líquido pleural e no soro de pacientes com derrame pleural para o diagnóstico de tuberculose pleural. MÉTODOS: Estudo transversal de teste diagnóstico. Amostras de líquido pleural e de soro de pacientes com derrame pleural e suspeita de tuberculose pleural foram avaliadas para a determinação da densidade óptica de IgA contra HspX utilizando ELISA indireto. RESULTADOS: Foram avaliadas amostras de líquido pleural e de soro de 132 pacientes: 97 com tuberculose pleural (grupo de estudo) e 35 com derrame pleural por outras causas (grupo controle). A dosagem de IgA em líquido pleural foi capaz de discriminar os pacientes com tuberculose pleural dos controles. A sensibilidade do teste em líquido pleural e em soro foi, respectivamente, de 69 por cento e 30 por cento, enquanto a especificidade foi de 83 por cento e 84 por cento, respectivamente. CONCLUSÕES: Os dados sugerem o potencial da utilização deste teste no diagnóstico de tuberculose pleural. Estudos com amostras maiores e em diferentes cenários epidemiológicos são necessários.

OBJECTIVE: To evaluate the accuracy of determining specific IgA to HspX recombinant antigen in pleural fluid and serum samples for the diagnosis of pleural tuberculosis in patients with pleural effusion. METHODS: This was a cross-sectional study. Serum and pleural fluid samples of patients with pleural effusion and suspected of having pleural tuberculosis were tested with indirect ELISA in order to determine the optical density of specific IgA to HspX. RESULTS: We evaluated serum and pleural fluid samples from 132 patients: 97 diagnosed with pleural tuberculosis (study group) and 35 diagnosed with pleural effusion due to other causes (control group). The determination of IgA in pleural fluid satisfactorily discriminated between pleural tuberculosis patients and control patients. The sensitivity of the test in pleural fluid and in serum was 69 percent and 30 percent, respectively, whereas the specificity was 83 percent and 84 percent, respectively. CONCLUSIONS: Our data suggest that this test can be used in the diagnosis of pleural tuberculosis. Further studies, involving larger patient samples and different epidemiological scenarios, are warranted.

Diagnostic accuracy of immunological methods in patients with tuberculous pleural effusion from Venezuela / Precisión diagnóstica de métodos inmunológicos en pacientes con tuberculosis pleural de Venezuela

In recent years, better diagnostics for tuberculosis (TB) has received increasing attention, especially the diagnosis of tuberculous pleural effusion, which is difficult and at present the main tool in TPE diagnostic is pleural effusion smear and culture, but unfortunately, sensitivities are low, therefore better TPE diagnostic tools are needed. The aim of this study was to find a diagnostic algorithm to assess the progress in TPE diagnostic at the Hospital Vargas de Caracas, that permits identification of the majority of patients, at a satisfactory cost-benefit ratio, evaluating the levels of IFN-g and IL-12p40 in pleural effusion and serum, as well as the antibody reactivity in order to compare it with microbiological tests. A total of 60 individuals with pleural effusion were studied; 20 patients with tuberculous pleural effusion (TPE) formed the patient group and 40 patients with non-tuberculous pleural effusion (NTPE) formed the control group. The levels of IFN-g and IL-12p40 in effusion and serum and class and subclasses of IgG reactivity to Mycobacterium tuberculosis antigens were measured by ELISA. The utility of these methods for diagnosis of TPE was evaluated using receiver operating characteristic (ROC) curve analysis. The results of the 11 immunological methods evaluated showed that the anti-PPD IgG2 method was able to reach the highest specificity of 95% (CI: 88.3-101.8), positive predictive value (PPV)=75 (at 30% sensitivity); while that the overall sensitivity of methods was between 95% and 30%, of these, two methods reached higher sensitivities; increased levels of pleural IFN-g, with a sensitivity of 95% (CI: 85.5-104.5) with the highest negative predictive value (NPV)=97, (at 82.5% specificity), followed by decreased levels of serum IL-12p40 with a sensitivity of 95% (CI: 85.5-104.5), NPV=95.2 (at 50% specificity). In contrast, microbiological methods showed that smear had a sensitivity of only 20%, while smear plus ...

Recientemente existe un gran interés hacia un mejor y más rápido diagnóstico de tuberculosis (TB), especialmente de tuberculosis pleural, el cual es difícil. Al presente las principales herramientas diagnósticas son la baciloscopia y el cultivo de líquido pleural; desafortunadamente, las sensibilidades de estos métodos son bajas, por lo que el desarrollo de nuevas herramientas diagnósticas es necesario. El objetivo del presente estudio consistió en encontrar un algoritmo que permita la rápida identificación de la mayoría de los pacientes con TB pleural que ingresan en el Hospital Vargas de Caracas a un buen costo-beneficio. Para esto se evaluaron los niveles de las citocinas Interferón-gamma (IFN-g) y la Interleucina 12p40 (IL-12p40) en líquido pleural y suero, así como la reactividad de anticuerpos contra antígenos de Mycobacterium tuberculosis. Se estudiaron 60 individuos con derrame pleural; 20 individuos con líquido pleural tuberculoso (LPT) conformaron el grupo de pacientes y 40 individuos con líquido pleural no tuberculoso (LPNT) el grupo de controles. La técnica de inmunoensayo de ELISA fue utilizada para medir los niveles de IFN-g y IL-12p40; así como las reactividades de los diversos isotipos y subclases de inmunoglobulina G (IgG) frente a antígenos del bacilo. La utilidad de los métodos fue evaluada utilizando el análisis de las curvas ROC (receiver operating characteristic). Los resultados de los 11 métodos inmunológicos evaluados mostraron que el método IgG2 anti-PPD alcanzó la mayor especificidad de 95%, (CI: 88,3-101,8) con un valor predictivo positivo (VPP) de 75. La sensibilidad de los métodos estuvo entre 30% y 95%; dos métodos alcanzaron altas sensibilidades: los altos niveles de IFN-g en líquido pleural, con sensibilidad de 95% (CI: 85,5-104,5), con un valor predictivo negativo (VPN) de 97, seguido de los bajos niveles de IL-12p40 en suero, con una sensibilidad de 95% (CI: 85,5-104,5) con un VPN de 95,2. En contraste, ...

Interlukin-8 and its value in differntiation of pleural effusion

This study was conducted on 50 patients [30 males and 20 females] with pleural effusion of different etiologies classified into five groups. The results obtained have shown that IL-8 was found in pleural fluid of all patients with the highest levels in empyema, then parapneumonic, tuberculous malignant and transudative effusion, respectively, while it was found in low levels in the blood of all patient and control groups with no significant differences between them. Comparison between IL-8 levels in exudative and transudative effusions has shown that it was significantly higher in exudative type. There was a significant positive correlation between pleural and serum IL-8 levels in transudative group only and it was significantly higher in infectious than in noninfectious effusions

Immunological study in pleural effusion.

Thirty patients of pleural effusion (25 tubercular, 5 malignant) were studied for enumeration of T and B cell percentage in pleural fluid (PF) and peripheral blood (PB) along with estimation of IgG, IgA and IgM. Ten healthy subjects were taken as controls. T cell percentage was significantly low and B cell percentage high in the PB of patients with effusion compared with controls. Comparing malignancy and tuberculosis patients it was seen that in both T cells in PF were higher and B cells lower compared with their respective values in PB. Significantly increased percentage of T cells in PF indicates either an active sequestration in PF or the presence of suppressor adherent cells in PB. However, T and B cell percentage in PB and PF were not significantly different in the two study groups. PB immunoglobulin (IgG, IgA, IgM) levels in patients were higher as compared to those in the controls, without significant difference in their levels in the two study groups. Ratio of PF/PB values for various immunoglobulins was less than unity but a cut-off point of 0.6 for IgG & IgA and 0.5 for IgM worked out as pointer for differentiating between malignant and tubercular effusions.

T-cell differentiation antigens and antigenic lymphocyte reactivity in pleural effusions.

Blood and pleural effusion mononuclear cells from thirteen patients were examined for the expression of T lymphocyte differentiation antigens as well as in vitro thymidine incorporation. The ratio of T4 to T8 cells was significantly greater among pleural effusion lymphocytes than among blood lymphocytes. Effusion lymphocyte responses to phytohaemagglutinin were less than those of blood lymphocytes. Unstimulated thymidine incorporation was greater in pleural effusion lymphocytes. Antigen-stimulated lymphocyte reactivity was not consistently greater in either blood or effusion lymphocytes. Lymphocytes from tuberculous effusions all reacted to tuberculin. Pleural effusion lymphocytes, regardless of the etiology of the effusion, possessed the same range of antigenic specificities as did blood lymphocytes. Therefore, effusion lymphocyte responsiveness to tuberculin does not prove the presence of tuberculous pleurisy but does indicate sensitisation to tuberculin.