RESUMO
This study was aimed at investigating alternate methods for serodiagnosis of tuberculosis (TB), which are needed because bacteriologic diagnosis of childhood TB is difficult. A selection of 80 serum and saliva samples were tested from Warao indigenous children under 15 years of age; 34 high TB suspects (28 positive and 6 negative for the tuberculin skin test, TST) and 46 healthy contact children (32 positive and 14 negative for the TST). Several enzyme-linked immunosorbent assay (ELISA) serological tests were developed to test for Mycobacterium tuberculosis-specific antibodies, including serum IgA, IgG, IgE, and secretory IgA (sIgA) in saliva against 3 specific antigens (PPD, HSP60, 38 kDa). Of these, 2 antigens, PPD and 38 kDa, showed significantly higher reactivity. The sensitivity and specificity of these tests for diagnosis remained limited, between 26.5% and 38.2%, and 77.4% and 97%, respectively. Of all the samples studied and combinations realized between all isotypes and antigens combined with 3 isotypes (anti-PPD IgG, IgE, and anti-38kDa sIgA) managed to detect the largest number of patients, showing an improved sensitivity level of 64.7%, although specificity levels dropped to 81.8%. These results were compared with the Omega diagnostics commercial kit results. The commercial kits showed significantly lower reactivity (sensitivity of 20% and 13.33% to Myco G and Complex Plus, respectively) and a specificity of 100%. This study shows that in indigenous populations of Venezuela, where invasive procedures cannot be used to select samples but evaluation with a chest X-ray for radiological studies is available, the combination of 3 specific isotypes may be a useful tool to increase diagnostic accuracy with pulmonary TB in this population, when used together with clinical and epidemiological criteria.
Assuntos
Anticorpos Antibacterianos/imunologia , Imunoglobulinas/análise , Indígenas Sul-Americanos , Mycobacterium tuberculosis/imunologia , Tuberculose/diagnóstico , Adolescente , Anticorpos Antibacterianos/sangue , Antígenos de Bactérias/imunologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulinas/imunologia , Lactente , Masculino , Sensibilidade e Especificidade , Teste Tuberculínico/métodos , Tuberculose/epidemiologia , Tuberculose/imunologia , Venezuela/epidemiologiaRESUMO
This study was aimed at investigating alternate methods for serodiagnosis of tuberculosis (TB), which are needed because bacteriologic diagnosis of childhood TB is difficult. A selection of 80 serum and saliva samples were tested from Warao indigenous children under 15 years of age; 34 high TB suspects (28 positive and 6 negative for the tuberculin skin test, TST) and 46 healthy contact children (32 positive and 14 negative for the TST). Several enzyme-linked immunosorbent assay (ELISA) serological tests were developed to test for Mycobacterium tuberculosis-specific antibodies, including serum IgA, IgG, IgE, and secretory IgA (sIgA) in saliva against 3 specific antigens (PPD, HSP60, 38 kDa). Of these, 2 antigens, PPD and 38 kDa, showed significantly higher reactivity. The sensitivity and specificity of these tests for diagnosis remained limited, between 26.5 percent and 38.2 percent, and 77.4 percent and 97 percent, respectively. Of all the samples studied and combinations realized between all isotypes and antigens combined with 3 isotypes (anti-PPD IgG, IgE, and anti-38kDa sIgA) managed to detect the largest number of patients, showing an improved sensitivity level of 64.7 percent, although specificity levels dropped to 81.8 percent. These results were compared with the Omega diagnostics commercial kit results. The commercial kits showed significantly lower reactivity (sensitivity of 20 percent and 13.33 percent to Myco G and Complex Plus, respectively) and a specificity of 100 percent. This study shows that in indigenous populations of Venezuela, where invasive procedures cannot be used to select samples but evaluation with a chest X-ray for radiological studies is available, the combination of 3 specific isotypes may be a useful tool to increase diagnostic accuracy with pulmonary TB in this population, when used together with clinical and epidemiological criteria.
Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Criança , Adolescente , Anticorpos Antibacterianos , Imunoglobulinas , Tuberculose , Estudos de Casos e Controles , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Indígenas Sul-Americanos , Sensibilidade e Especificidade , Teste Tuberculínico , VenezuelaRESUMO
To study the effect of Zn on the proliferative response of normal human lymphocytes, ZnCl2 at a final concentration of 10(-4) M was added to cultures of peripheral blood mononuclear cells (PBMC) stimulated with concanavalin A (Con A) and to autologous mixed lymphocyte cultures of responder T lymphocytes and irradiated autologous non-T cells. Addition of Zn increased by about 50% the synthesis of DNA in cultures stimulated with either 10 or 20 micrograms/ml of Con A and markedly enhanced the autologous mixed lymphocyte reaction, which increased about 5-fold in the presence of Zn. In a narrow dose range, Zn induced per se the incorporation of [3H]thymidine by PBMC, with maximal effects in cultures stimulated with 10(-4) M ZnCl2. The percentage of cells expressing receptors for IL-2 and transferrin as assessed by immunofluorescence with the monoclonal antibodies (mAb) anti-Tac and OKT9, respectively, significantly increased when PBMC were stimulated with 10(-4) M ZnCl2 alone. Maximal [3H]thymidine incorporation and maximal percentage of cells bearing those activation markers were observed on day 6 of culture. Thus, the increase in the uptake of [3H]thymidine induced by Zn is not artifactual but due to progression in the cell cycle. Incubation with the mAb anti-Tac significantly inhibited the proliferative response to Zn, indicating that this requires binding of IL-2 to its receptor. However, addition of human recombinant IL-2 did not increase [3H]thymidine incorporation by PBMC cultured in the presence of ZnCl2.