Cytokine mRNA Expression and Proliferative Responses Induced by Pertussis Toxin, Filamentous Hemagglutinin, and Pertactin ofBordetella pertussisin the Peripheral Blood Mononuclear Cells of Infected and Immunized Schoolchildren and Adults

Abstract

Pertussis infection is increasingly recognized in older children and adults, indicating the need of booster immunizations in these age groups. We investigated the induction of pertussis-specific immunity in schoolchildren and adults after booster immunization and natural infection. The expression of mRNA of gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-4, and IL-5 in the peripheral blood mononuclear cells (PBMCs) was assayed by reverse transcription-PCR. The PBMCs of 17 children immunized with one dose of an acellular vaccine containing pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) significantly proliferated in vitro after stimulation with the vaccine antigens. The PBMCs of seven infected individuals markedly proliferated in the presence of PT and FHA, but the cells of only two of these subjects responded to PRN. At least one of the antigens induced mRNA for IL-4 and/or IL-5 in the cells of 93% of tested vaccinees and patients, and FHA induced IFN-γ mRNA in the cells of two-thirds of them. Expression of mRNA for IFN-γ correlated with the production of the cytokine protein. Anti-FHA immunoglobulin G antibodies significantly correlated with FHA-induced proliferative responses both before and after immunization. These results show that booster immunization with acellular pertussis vaccine induces both antibody- and cell-mediated immune responses in schoolchildren. Further, booster immunization and natural infection seem to induce the expression of mRNA of T-helper 1 (Th1) and Th2 type cytokines in similar manners. This observation supports the use of acellular pertussis vaccines for booster immunizations of older children, adolescents, and adults.

Cell-Mediated Immune Responses in Four-Year-Old Children after Primary Immunization with Acellular Pertussis Vaccines

“…In particular, IL-5 levels were low or not detectable in aP-SB recipients, who included the highest IL-5 producers at the earlier age (4). In previous observations of ours (4) and others (13,28), a mixed type 1-type 2 profile in PBMC of aP vaccine recipients was found. It should be stressed here that the interpretation of these data is necessarily limited by the cross-sectional rather than longitudinal nature of the study, as all CMI ϩ children 48 months of age who were examined belonged to a subcohort of children who were not examined or were CMI Ϫ at 7 months of age and thus did not produce cytokines in antigen-stimulated PBMC (4).…”

“…Interestingly, no child examined showed elevation of Ab titer against PT, as occurs during disease, suggesting that diseasefree infection with B. pertussis (or even cross-reacting bacteria) may more easily recall CMI than Ab response to PT in vaccinated children. In this context, the recent observation by He et al (13) that CMI and Ab responses to PRN and FHA in schoolchildren who were recipients of aP vaccines were significantly correlated whereas their PBMC-proliferative and IgG Ab responses to PT were not is interesting.…”

“…We have shown that CMI persisted in these children up to 20 months of age (4,7,29,36), and a correlation between clinical efficacy and percentage of vaccinees acquiring CMI to pertussis toxin (PT) was apparent (7). Coupled with evidence from experimental models of infection (18,23,26), the above-mentioned studies suggested that CMI induction could play a role in protection induced by vaccination and in its persistence despite the early fall of antibody (Ab) levels (4,7,11,13,29,36).…”

“…Despite recent experimental and clinical investigations of induction and expression of immune responses against Bordetella pertussis, the mechanisms underlying protection from pertussis are not completely understood (8,15,25). Although data from experimental infections suggest that both T and B memory cell compartments are involved (18,20,23,26), it is not clear which component(s) of adaptive immune responses mediates protection induced by vaccination in infants and to what extent the mechanisms of protection induced by whole-cell pertussis (wP) or acellular pertussis (aP) vaccines differ from each other (4,7,13,29,36). Conflicting information has been generated about the existence of serologic correlates of protection (1,9,10,21,22,32,33).…”

Human Monocytic U937 Cells Kill Salmonella In Vitro by NO-Independent Mechanisms

“…The expression of iNOS mRNA by transfected U937 cells was studied by reverse-transcriptase PCR (RT-PCR) with primers specific for human ␤-actin (5Ј-GAA ATC GTG CGT GAC ATT AAG GAG-3Ј and 5Ј-ATA CTC CTG CTT GCT GAT CCA CAT-3Ј) (8) and iNOS (5Ј-ATG CCA GAT GGC AGC ATC AGA-3Ј and 5Ј-ACT TCC TCC AGG ATG TTG TA-3Ј) (26). Details of mRNA extraction and cDNA synthesis were described previously (8). Initial denaturation at 94°C for 5 min and final extension at 72°C for 5 min were used for both primer pairs.…”