Detecção de anticorpos IgG específicos para os antígenos ESAT-6, CFP-10, 85B, 16kDa e HBHA em pacientes com tuberculose ativa: importância no diagnóstico e efeito do tratamento quimioterápico

Abstract

Detection of specific antibodies may represent a valuable tool in the diagnosis of tuberculosis (TB). In this work levels of IgG antibodies against ESAT-6, CFP-10, 85B, 16kDa and HBHA M. tuberculosis antigens were measured in 102 serum samples from pulmonary TB patients grouped as: 1) active TB patients (n=33); 2) patients who had received 1 to 3 months of anti-TB chemotherapy (n=47); and, 3) patients who had completed 6 months of chemotherapy (n=22). A control group formed by 38 BCG vaccinated healthy controls was included. levels of IgG1, IgG2 and IgG4 were also quantified in the serum of patients with active TB against the ESAT-6 and CFP-10 antigens. Elevated levels of IgG against ESAT-6, CFP-10, 85B, 16kDa and HBHA were detected in active TB patients in comparison with the group of patients that completed the treatment (p<0,05) and in comparison with the healthy control group (p<0,05). Levels of IgG against 16kDa had a peak after 1-3 months of chemotherapy. The ROC curves indicated sensitivity of 85% (ESAT-6), 94% (CFP-10), 91% (85B) 61% (16kDa) and 70% (HBHA), and specificity of 89% (ESAT-6), 87% (CFP-10), 82% (85B), 89% (16K) e 84% (HBHA). The area under the ROC curve was larger when the ESAT-6 (area = 0.956, IC 95%: 0.865 to 0.985) and CFP-10 (area = 0.942, IC 95% per cent: 0.859 to 0.983) antigens were used, in comparison to 16kDa (area = 0.809, IC 95%: 0.699 to 0.893) and HBHA (área = 0,805, IC 95%: 0,694 to 0,890). The 85B antigen (área = 0,909, IC 95%: 0,817 to 0,964) did not exhibit statistic difference in relation to the 16kDa antigen in ROC curve analysis. A predominant detection of IgG1 against ESAT-6 and CFP-10 was observed in active TB patients. Detection of IgG antibodies to ESAT-6 and CFP-10 may represent an additional tool in TB diagnosis, and may be potentially useful as indicative of the treatment success.