Increasing evidence suggests that cell-mediated immunity (CMI) is involved in immune response against Bordetella pertussis. However, there are practically no studies evaluating the significance of pertussis-specific CMI in relation to protection against clinical pertussis.Methods.
An outbreak of pertussis was studied prospectively in 13-year-old pupils in a rural school. B. pertussis infection was diagnosed by culture, microagglutination and enzyme immunoassay serology with the use of pertussis toxin, filamentous hemagglutinin and pertactin as antigens. Pertussis-specific CMI responses were assessed by in vitro proliferation assay of peripheral blood mononuclear cells.Results.
At the initial sampling 7 of 22 children had symptoms suggestive of pertussis and 15 were asymptomatic. Of the latter 3 remained healthy, 8 were later confirmed to have had asymptomatic infection, 3 developed laboratory-confirmed pertussis and 1 developed cough without laboratory evidence of pertussis. Initial in vitro proliferations of peripheral blood mononuclear cells induced by pertussis toxin, filamentous hemagglutinin and/or pertactin were positive in all 3 healthy children, in 6 of 8 children who had asymptomatic infection, but in none of the 3 children who later developed pertussis. Although some children who remained healthy had high values of antibodies, no clear association was found between initial serum antibody values and clinical outcome.Conclusions.
These preliminary data suggest that CMI may have an important role in protection against clinical pertussis but do not exclude a role for antibodies. Furthermore the results stress a multifactorial nature of the immune protection against B. pertussis.