The Middle East respiratory syndrome coronavirus (MERS-CoV) has been recognized as a highly pathogenic virus to humans that infects the respiratory tract and is associated with high morbidity and mortality. Studies in animal models suggest that MERS-CoV infection induces a strong inflammatory response, which may be related to the severity of disease. Data showing the cytokine profiles in humans during the acute phase of MERS-CoV infection are limited. In this study, we have analyzed the profile of cytokine responses in plasma samples from patients with confirmed MERS-CoV infections (n = 7) compared to healthy controls (n = 13). The cytokine profiles, including T helper (Th) 1, Th2 and Th17 responses, were analyzed using cytometric bead array (CBA). A prominent pro-inflammatory Th1 and Th17 response was clearly seen in patients with MERS-CoV infection, with markedly increased concentrations of IFN-γ, TNF-α, IL-15 and IL-17 compared to controls. IL-12 expression levels showed no difference between patients with MERS-CoV infection and the healthy controls despite the significantly increased levels of IFN-α2 and IFN-γ (P < .01). No changes were observed in the levels of IL-2, IL-4, IL-5, IL-13, and TGF-α (P > .05). Our results demonstrate a marked pro-inflammatory cytokine response during the acute phase of MERS-CoV infection in humans.

Although anticapsular antibodies confer serotype-specific immunity to pneumococci, children increase their ability to clear colonization before these antibodies appear, suggesting involvement of other mechanisms. We previously reported that intranasal immunization of mice with pneumococci confers CD4+ T cell–dependent, antibody- and serotype-independent protection against colonization. Here we show that this immunity, rather than preventing initiation of carriage, accelerates clearance over several days, accompanied by neutrophilic infiltration of the nasopharyngeal mucosa. Adoptive transfer of immune CD4+ T cells was sufficient to confer immunity to naïve RAG1−/− mice. A critical role of interleukin (IL)-17A was demonstrated: mice lacking interferon-γ or IL-4 were protected, but not mice lacking IL-17A receptor or mice with neutrophil depletion. In vitro expression of IL-17A in response to pneumococci was assayed: lymphoid tissue from vaccinated mice expressed significantly more IL-17A than controls, and IL-17A expression from peripheral blood samples from immunized mice predicted protection in vivo. IL-17A was elicited by pneumococcal stimulation of tonsillar cells of children or adult blood but not cord blood. IL-17A increased pneumococcal killing by human neutrophils both in the absence and in the presence of antibodies and complement. We conclude that IL-17A mediates pneumococcal immunity in mice and probably in humans; its elicitation in vitro could help in the development of candidate pneumococcal vaccines.

Streptococcus pneumoniae causes significant morbidity and mortality especially in children. Some pneumococcal protein antigens can protect mice against infection. Little information is available concerning the nature of naturally acquired protective immunity to pneumococci in humans induced by these antigens. This study investigates the relationships between systemic and local antibody production and carriage in children. Children undergoing adenoidectomy (n=112, ages 2-12 years) were studied. Nasopharyngeal swabs were collected for pneumococcal culture. Serum and saliva were assayed for antibodies to several pneumococcal proteins: choline binding protein A (CbpA), pneumolysin (Ply), pneumococcal surface adhesin A (PsaA) and pneumococcal surface protein A (PspA). Adenoidal mononuclear cells (MNC) were cultured with pneumococcal culture supernatants or recombinant proteins. Cell culture supernatants were analyzed for antigen-specific antibodies. Carriage rates fell with age and serum levels of anti-CbpA, Ply and PspA rose. Anti-CbpA and -Ply serum and salivary IgG antibody levels were higher in children who were culture negative than those who were colonized. Antigen stimulation increased respective antigen-specific IgG production by adenoidal MNC and these responses were greater in those who were colonized than in culture-negative children. Antibodies to CbpA and Ply may protect children aged 2 years and older against pneumococcal colonization. Adenoids may be important local induction and effector sites for both mucosal and systemic antibody production to pneumococcal proteins in children.

Regulatory T cells (Treg) diminish immune responses to microbial infection, which may contribute to preventing inflammation-related local tissue damage and autoimmunity but may also contribute to chronicity of infection. Nasopharyngeal carriage of pneumococcus is common in young children and can persist for long periods but it is unknown whether the presence of Treg in the nasopharynx contributes to this persistence. We have investigated the numbers and activities of Foxp3+Treg in adenoidal tissues and their association with pneumococcal carriage in children. Expression of Treg cell-related markers including Foxp3, CD25, CD39, CD127 and CLTA4 were analysed by flow-cytometry in adenoidal mononuclear cells (MNC) and PBMC from children. Unfractionated MNC or Treg-depleted MNC were stimulated with a pneumococcal whole cell antigen (WCA) and T cell proliferation measured. Cytokine production by MNC was measured using a cytometric bead array. Higher numbers of CD25highFoxp3high Treg expressing higher CD39 and CTLA4 were found in adenoidal MNC than in PBMC. Children with pneumococcus positive nasopharyngeal cultures had higher proportions of Treg and expressed higher levels of CD39 and CTLA-4 than those who were culture negative (−). WCA induced adenoidal Treg proliferation which produce IL10 but not IL17, and CD4 T cell proliferation in Treg-depleted MNC was greater in pneumococcal culture positive than negative children. Significant numbers of Treg with an effector/memory phenotype which possess a potent inhibitory effect, exist in adenoidal tissue. The association of pneumococcal carriage with an increased frequency of adenoidal Treg suggests that Treg in nasal-associated lymphoid tissue (NALT) may contribute to the persistence of pneumococcus in children. Further studies to determine what component and mechanisms are involved in the promotion of Treg in NALT may lead to novel therapeutic or vaccination strategy against upper respiratory infection.

These data suggest that Ply induces CD4 T cell proliferative responses with production of IFN- gamma and TNF- alpha in PBMCs or of IFN- gamma and IL-10 in adenoidal MNCs, which may be important in modulating pneumococcal carriage in children.

Previous studies in children have shown that Haemophilus influenzae type b (Hib) polysaccharide conjugate vaccines can reduce nasopharyngeal carriage of H. influenzae and provide herd immunity and suggest that this effect is mediated through mucosal antibodies. As this phenomenon may operate in other invasive bacterial infections which are propagated by nasopharyngeal carriage, mucosal antibody responses to meningococcal C conjugate and A/C polysaccharide vaccines were investigated. A total of 106 school children aged 11 to 17 years were randomized to receive a single dose of either conjugate or polysaccharide vaccine in an observer-blind study. Before and at 1, 6, and 12 months after immunization, samples of unstimulated saliva were collected and assayed by enzyme-linked immunosorbent assay for group C polysaccharide-specific immunoglobulin A (IgA), IgA1, IgA2 and secretory component, IgG antibodies, and total IgG and IgA. A subset of serum samples were also assayed for specific IgA and IgG antibodies. The concentrations of specific IgA and IgG in saliva were expressed both as nanograms per milliliter and as nanograms per microgram of total IgA or IgG. One month after immunization, significant increases in antibody titers (both IgA and IgG) were observed in saliva in both groups. There were significant subsequent falls in antibody titers by 6 months. Anti-meningococcal C-specific secretory component and IgA antibody titers were closely correlated (r ‫؍‬ 0.85, P < 0.001), but there was no significant correlation between salivary and serum IgA titers, suggesting that IgA antibodies are locally produced. Significant correlation was found between salivary and serum IgG titers (r ‫؍‬ 0.52, P < 0.01), suggesting that salivary IgG may be serum derived. Compared with polysaccharide vaccine, the conjugate vaccine induced significantly higher salivary IgG responses (P < 0.05), although there were no significant differences between salivary IgA responses to the two vaccines. The conjugate vaccine induced greater salivary IgG responses than a polysaccharide vaccine. Both vaccines induced significant salivary IgA antibodies. Further studies are needed to establish the functional significance of these mucosal responses.The increased incidence of septicemia and meningitis due to group C Neisseria meningitidis in recent years in the United Kingdom, particularly among older children and young adults, has created considerable public concern (30). Currently licensed polysaccharide vaccines against group C meningococcal disease do not induce immunological memory and are poorly immunogenic in children under the age of 2 years (4, 13, 21). New conjugate vaccines have been shown to induce greater immunoglobulin G (IgG) and bactericidal antibody responses (S. Choo, Q. Zhang, J. Everard, C. Goilav, E. Hatzmann, J. Zuckermann, and A. Finn, Arch. Dis. Child 80:A71, abstr. G207, 1999), to be immunogenic in infants, and to induce immunological memory (11,(22)(23)(24)34).Haemophilus influenzae type b (Hib) conjugate vaccines have been used ...

In this population, T cell-mediated immunological memory potentially capable of pathogen clearance and immune surveillance is common but is not associated with the absolute interruption of pneumococcal carriage. How this naturally acquired immune memory influences pneumococcal vaccine efficacy remains to be determined.

Studies of mice suggest that pneumococcal proteins, including PspA, pneumolysin, PsaA, and CbpA, are promising vaccine candidates. To determine whether these proteins are good mucosal immunogens in humans, adenoidal lymphocytes from 20 children who had adenoidectomies were isolated and tested by ELISpot for antigen-specific antibody-secreting cells (ASCs). Cells were also cultured for 7 days in the presence of a concentrated culture supernatant (CCS) from a type 14 strain of pneumococcus which contained secreted pneumococcal proteins, including PspA, pneumolysin, PsaA, and CbpA, and then tested by ELISpot. ELISpot assays done on freshly isolated cells detected ASCs to all four antigens in most children studied. However, there were differences both between antigens and between isotypes. The densities of immunoglobulin G (IgG) ASCs against both PsaA and CbpA were significantly higher than those of ASCs for PspA and PdB (pneumolysin toxoid B) (P < 0.001). For all antigens, the numbers of IgA ASCs tended to be lower than those