Mucosal Antibodies to Haemophilus influenzae Type b Capsular Polysaccharide

Abstract

ABSTRACf. Levels of salivary antibodies directed againstHaemophilus influenzae b (Hib) capsule, measured by ELISA and standardized to the total salivary IgA, were compared among 57 patients with Hib infections, 117 household and 49 day care contacts of patients, and 53 control individuals with no known contact with Hib. Nineteen of the household or day care contacts were throat or nasopharyngeal culture positive for Hib. Eighty % of evaluable patients had polyribosylribitol phosphate (PRP)-specific IgA in their saliva, compared with 36% of contacts who were throat or nasopharyngeal culture positive for Hib, 53% of contacts who were throat or nasopharyngeal culture negative for Hib, and 30% of control children. In patients, no correlation between age and level of salivary anti-PRP antibody was seen, but patients less than 3 yold were more likely to have these antibodies than were older patients. Salivary PRP-specific IgA antibodies, associated with either Hib colonization or PRP vaccination, tended to decline over time. Thus, PRP-specific IgA antibodies can be identified in the saliva of children over a wide age range, including those colonized with Hib or vaccinated with PRP, but these antibodies appear to decline after antigenic stimulation ceases.

Subclass distribution of IgA antibodies in saliva and serum after immunization withHaemophilus influenzaetype b conjugate vaccines

“…The different distribution of IgA subclasses in saliva and serum after Hib immunization strengthens the view of independence of mucosal and systemic immune responses. Mucosal antibodies against Hib PS have been reported to develop at an earlier age than the serum response, both after Hib infection and after vaccination with Hib PS vaccine [24–26]. It has been speculated that to some extent the early mucosal response compensates for the poor serum antibody response of young children to PS antigens.…”

The First Dose of aHaemophilus influenzaeType b Conjugate Vaccine Reactivates Memory B Cells: Evidence for Extensive Clonal Selection, Intraclonal Affinity Maturation, and Multiple Isotype Switches to IgA2

“…It seems likely that the origin of these cells is related to the acquirement of natural Ab to HibCP that occurs within the first years of life (60). The mucosa-associated lymphoid tissues are candidate sites for engagement of B cells producing this natural Ab, because several bacteria capable of inducing anti-HibCP Abs regularly colonize the mucosal surfaces from infancy, including Hib itself (61) and E. coli K100 (62).…”

Antigenic Diversity and Gene Polymorphisms in Haemophilus influenzae

“…The human respiratory tract is bathed with antibody-containing (mostly immunoglobulin A [IgA]) secretions, and in H. influenzae-immune individuals, H. influenzae-specific antibodies are found in these secretions. A total of 80% of Hibinfected infants, 36% of colonized contacts of these patients, 53% of noncolonized contacts, and 30% of control children demonstrated antibodies specific for the type b capsule in their salivary secretions (29). This study assessed the point prevalence of salivary antibody against just one H. influenzae antigen (the type b capsule) and did not explore the relationship between antibody response and persistence of colonization, nor did it explore the prevalence of antibodies directed at other H. influenzae antigens.…”