Influence of age and carriage status on salivary IgA to Neisseria meningitidis

Abstract

Asymptomatic carriage of Neisseria meningitidis is common (5-35% of individuals) while the incidence of invasive meningococcal disease is fairly low (<1-5 per 100,000 per annum in Europe). Naturally acquired protective immunity may account for this difference. In this study, we investigated the relationship between anti-meningococcal salivary IgA and age and carriage. We showed that salivary IgA to a range of meningococcal antigens increased successively with age with some specificity for commonly circulating serosubtypes. In a group of 258 students 37 (14%) of whom were carriers of N. meningitidis serogroup B, higher levels of specific IgA were associated with carriage. Stratified analysis revealed a positive relationship between smoking and specific anti- N. meningitidis IgA independent of current carriage, weighted odds ratio (OR) 4.1 (95% CI 1.1-18) and OR 3.8 (95% CI 0.96-16) for reference strains B:1:P1.14 and B:4:P1.5,4 respectively. These data implicate IgA as a factor in host defence from meningococcal invasion, although the precise mechanisms remain uncertain.

Phase Variation Mediates Reductions in Expression of Surface Proteins during Persistent Meningococcal Carriage

“…Mucosal IgA responses to whole N. meningitidis cells and to PorA have also been detected (43,44). We demonstrated the presence of high levels of IgG antibodies specific for the homologous PorA variant in the majority of persistent carriers and high levels of anti-CapY specific IgG antibodies (Table 2 and Fig.…”

Absence of Mucosal Immunity in the Human Upper Respiratory Tract to the Commensal Bacteria Neisseria lactamica but Not Pathogenic Neisseria meningitidis during the Peak Age of Nasopharyngeal Carriage

“…In contrast to Nl, Nm does not induce this mitogenic B cell response. Without the potential shielding effects of innate IgM, colonizing Nm in early adulthood primes an adaptive immune response, inducing cellular memory (16) and T cell-dependent Ig production (13,14). This immunity is heavily regulated by Treg activity in the mucosa, which may prevent clearance of Nm, prolonging carriage but also predisposing the host to invasive disease (19).…”

“…Nm is carried by ϳ10% of the population at any one time (12). Asymptomatic carriage primes an adaptive immune response within 2 wk of colonization (13) and is associated with increased titers of salivary IgA (14) and serum IgG (15). We have demonstrated the presence of memory T cell responses to Nm outer membrane vesicles (OMV) in human palatine tonsils (PT) which increase with age (16).…”

Comparative Role of Immunoglobulin A in Protective Immunity against the Bordetellae

“…Clinical and experimental findings show that individuals deficient in the immunoglobulin A (IgA) isotype of antibodies, the main immunoglobulin in mucus secretions, are more susceptible to certain sinopulmonary infections (17,34,36). In animal studies, IgA is important to immunity against grampositive bacteria, such as Streptococcus pneumoniae (19,39).…”

“…These antibodies also effectively reduced the nasal carriage of influenza virus in a mouse model (34). However, there are conflicting reports regarding the contribution of IgA to immunity against gram-negative bacterial pathogens (1,17,18,22).…”