Prospective study of immune response in Brazilian children heavily exposed to Streptococcus mutans: influence of specific immune response in infection / Estudo prospectivo da resposta imunologica de crianças brasileiras altamente expostas ao Streptococcus mutans : influencia da especificidade da resposta imune na infeção

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Mutans streptococci (MS) are the main pathogens of dental caries. In this study we explored the influence of the muccosal immune system in the initial colonization by MS in children highly exposed to this microorganism. A total of 119 children, who were of 5 to 13 months of age, were enrolled in this prospective study. MS levels of infection were determined in cultures on mitis salivarius agar with bacitracin at baseline (T0), 6 (T6), 12 (T12) and 18 months (T18)-of follow-up. Saliva samples were also collected at all phases of the study for determination of the levels of antibodies IgA, IgA1 and IgM in ELISA assays. A subset of 21 MS-infected early between T0 and T6 were matched to other 21children, but who were not MS-infected. Patterns of IgA antibody reactivity to MS Ags were compared between these 21 pairs through assays of western blot. Intensities of IgAreactive bands were determined densitometrically and were expressed as arbitrary unit (au). Reactivities of salivary IgA antibodies to peptides derived from the GbpB sequence, which were predicted as having affinity to MHC of class II molecules were evaluated in multiplex with the help of the Luminex technology. Levels of antibody IgA in saliva increased with age (82.4-823.35 µg/ml), while levels of IgM remained at low levels (mean:4.2-2.78 µg/ml). The highest levels of MS infection in the infected group were observed at T6 (mean:45 cfu/plate). Robust responses to SM antigens were detected in children as early as 6 months of age. Only 38% of early-infected children carried IgA-reative GbpB while this antigen was recognized by the majority (73%) of children that were not infected by these microorganisms (chi-square, p<0.03). A peak of IgA response to GbpB occurred during the phase of highest SM infectious challenge (by T6). All the GbpB-derived peptides have shown reactivity with salivary IgA, independently of the status of MS infection. The results indicated that complex salivary IgA responses to MS Ags can occur by 6 months of age and that the patterns of salivary IgA specificities might influence in the susceptibility of initial infections to MS. Neither of the peptides tested corresponded to differences in response to the native protein observed between the pairs of children studied

ASSUNTO(S)

infection infecção immunoglobulin a sistema imune imunoglobulina a immune system

ACESSO AO ARTIGO

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