The secretory immunoglobulin A response to Mycobacterium tuberculosis in a childhood population

Abstract

We report on the measurement of saliva anti-Purified Protein Derivative sIgA and 38kDa antibodies from 127 children, of whom 31 were strong tuberculosis suspects and 96 were healthy contact children. The results concerning the percentage of children with antibody reactivity to PPD and 38kDa antigens showed that, of these 2 antigens, 38kDa induced higher reactivity in patients positive and negative for the Tuberculin Skin Test (28% and 16.6%, respectively) in comparison to controls positive and negative for the TST (11.7% and 7.1%, respectively). There was a statistically significant difference between patients positive and controls negative for the TST. In relation to the Purified Protein Derivative antigen, while 14.2% of patients positive for the TST showed antibody reactivity to the PPD antigen, no patients negative for the TST had reactivity to this antigen. The findings suggest that these two antigens seem be associated with a different development of the mucosal defence mechanisms mediated by sIgA against Mycobacterium tuberculosis. Key-words: Tuberculosis. Warao. Secretory IgA. Tuberculin skin test. RESUMOForam dosados anticorpos sIgA anti-Purified Protein Derivative e 38kDa da saliva de 127 crianças, das quais 31 eram de pacientes altamente suspeitos de tuberculose e 96 eram provenientes de crianças saudáveis, que tiveram contato com pacientes. Os resultados referentes à porcentagem de crianças, reativas ao PPD e ao antígeno 38kDa, mostraram que destes dois antígenos, o 38kDa induziu maior reatividade em pacientes positivos e negativos ao Tuberculin Skin Test (28% e 16,6%, respectivamente), em comparação aos controles positivos e negativos ao TST (11,7% e 7,1%, respectivamente). Houve diferença estatisticamente significativa entre pacientes positivos e controles negativos ao Tuberculin Skin Test. Em relação ao antígeno PPD, enquanto 14,2% de pacientes positivos ao TST mostraram anticorpos reativos ao antígeno Purified Protein Derivative, nenhum paciente negativo ao TST foi reativo ao antígeno. Os achados sugerem que, aparentemente, estes dois antígenos estão associados a desenvolvimento distinto dos mecanismos de defesa da mucosa mediados por sIgA contra Mycobacterium tuberculosis. Palavras-chaves: Tuberculose. Warao. IgA secretória. Teste cutâneo da tuberculina.

Antibody Responses to Mycobacterial Antigens in Children with Tuberculosis: Challenges and Potential Diagnostic Value

“…Hence, none of the antigens evaluated as of today was selected based on data in pediatric populations. As in adult TB serology, the earlier studies tested children's Ab responses to crude mixtures of components and products of mycobacteria, such as mycobacterial sonicates or purified protein derivative (PPD) (3,4,23,48,74). Mycobacterial sonicates are obtained from whole-cell lysates, and PPD, often also referred to as tuberculin, is obtained from filtrates of sterilized, concentrated cultures of M. tuberculosis or other mycobacteria.…”

“…These preparations are mixtures of a large variety of native, nonspecific mycobacterial antigens, including proteins, glycolipids, and polysaccharides. Studies assessing Ab responses to these antigen mixtures in children reported sensitivities ranging from 20% to 63% and specificities ranging from 40% to 97% (3,4,23,48,74). Several other studies evaluated a combination of antigens or antigen complexes, either in the form of commercially available kits or in the form of in-house enzyme-linked immunosorbent assays (ELISA), while others evaluated single antigens, such as mycobacterial pro- A few studies also included the evaluation of immune complexes (54,58).…”

Peran Imunitas Mukosa terhadap Infeksi Mycobacterium Tuberculosis

“…Di sisi lain, peran protektif imunitas humoral spesifik Mtb masih bersifat kontroversial. Beberapa tahun terakhir ini, beberapa bukti menunjukkan peran protektif antibodi terhadap Mtb 5,12 , di mana sIgA adalah isotope antibodi alami yang secara berlimpah dihasilkan oleh jaringan mukosa. 3 Sekitar 60% dari total immunoglobulin yang diproduksi oleh manusia adalah IgA.…”

“…Dari percobaan pada hewan, diketahui bahwa inokulasi atau pembiakan IgA untuk melawan antigen Mtb mengakibatkan hilangnya infeksi tuberkulosis pada paru, sehingga hal ini menjadi dasar pemberian vaksin intranasal pada Mtb. 12 lymph node (LDLN) sebelum proses priming sel T dapat muncul, sehingga membutuhkan waktu lebih lama. Faktor host juga diyakini berpengaruh pada respons sel T tersebut.…”

Purification and Characterisation of Badger IgA and Its Detection in the Context of Tuberculosis

“…When Conde et al evaluated the usefulness of detection of serum IgA and serum IgG antibodies directed against the mycobacterial P-90 antigen for the diagnosis of pulmonary TB in people, they found that an IgA-based ELISA was more sensitive and specific than one based on IgG [14]. IgA is the predominant Ig isotype in human mucosal tissue and comprises about 60% of the total immunoglobulin produced in humans [15]. Since M. bovis is primarily a respiratory pathogen in badgers [16], it would be beneficial to develop an immunological test to detect the local response to infection in badgers.…”