ANTIBODIES TO THREE MYCOBACTERIAL RECOMBINANT ANTIGENS, EVALUATION IN CHILDREN WITH PULMONARY TUBERCULOSIS.
Leonardo Silva de Araujo (FIOCRUZ); Terezinha M.martire (UNIRIO); Clemax C. Sant'anna (IPPMG/UFRJ); S. Lucena (HRPS); Ronir R. Luiz (FM/UFRJ); Marcus Barreto Conde (FM/UFRJ); Maria Helena Féres Saad (FIOCRUZ)
Resumo
Background: In spite of the advent of several proposed modalities in molecular and immunological methods of diagnostic, the diagnosis of pulmonary tuberculosis in children still a problem due the paucity of the clinical specimen. Several commercial kits are available however none is used in routine diagnostic laboratory. A rapid, simple and relatively inexpensive diagnostic test will be crucial to future control efforts. Use of antibody detection ELISA seems to be an attractive strategy to aim children tuberculosis diagnosis. Objective: To evaluate the IgG immune response of children with tuberculosis to a panel of three Mycobacterium tuberculosis recombinant protein antigens MPT-64, ESAT-6 and CFP-10. Design: Sera of 207 children, of which 104 with respiratory symptoms (50 with pulmonary tuberculosis and 54 with non-tuberculosis pulmonary disease) and 103 controls without respiratory symptoms were tested by ELISA. Results: Ninety-eight percent of patients were BCG-vaccinated, all children with respiratory symptoms were HIV-negative and two TB cases had acid fast bacilli (AFB) smear positive. IgG-ELISA sensitivity was 27 %, 20 % and 16 %, respectively for MPT-64, ESAT-6 and CFP-10 antigens at 95% of specificity. The mean level of IgG reactivity for all antigens in TB patients was significantly higher than in controls (P<0.001). Combining results of all antigens sensitivity increased to 48% followed by MPT-64+ESAT-6 = 40% MPT-64+CFP-10 = 39%, and ESAT-6+CFP-10 = 29%; although jeopardizing the specificity (86% and 90%, respectively). Conclusion: IgG-MPT-64 alone or plus ESAT-6 may be take into account as rapid adjuvant test to aim diagnosis of TB among suspected respiratory children, but other antigens must be evaluated to improve a multiplex ELISA for children pulmonary TB diagnosis.
Financial Support:CNPq, DECIT/CNPq, FAPERJ, Programa Cooperação Brasil x Alemanha.