The autosomal dominant hyper-IgE syndrome (HIES, 'Job's syndrome') is characterized by recurrent and often severe pulmonary infections, pneumatoceles, eczema, staphylococcal abscesses, mucocutaneous candidiasis, and abnormalities of bone and connective tissue1,2. Mutations presumed to underlie HIES have recently been identified in stat3, the gene encoding STAT3 (signal transducer and activator of transcription 3) (refs 3, 4). Although impaired production of interferon-γ and tumour-necrosis factor by T cells5, diminished memory T-cell populations, decreased delayed-type-hypersensitivity responses and decreased in vitro lymphoproliferation in response to specific antigens6 have variably been described, specific immunological abnormalities that can explain the unique susceptibility to particular infections seen in HIES have not yet been defined. Here we show that interleukin (IL)-17 production by T cells is absent in HIES individuals. We observed that ex vivo T cells from subjects with HIES is consistent with a crucial role for STAT3 signalling in the generation of T H 17 cells7-14. T H 17 cells have emerged as an important subset of helper T cells15 that are believed to be critical in the clearance of fungal16 and extracellular bacterial17 infections. Thus, our data suggest that the inability to produce T H 17 cells is a mechanism underlying the susceptibility to the recurrent infections commonly seen in HIES. HHS Public AccessWe studied three groups of subjects: healthy controls with no apparent immunological defects, HIES individuals with defined mutations in stat3, and individuals (termed 'HIESlike') with some combination of elevated IgE, atopic dermatitis, skeletal abnormalities and susceptibility to infection, but without recurrent staphylococcal abscesses or candidiasis or stat3 mutations (Table 1).We observed that IL-17-producing T cells were barely detectable among peripheral blood mononuclear cells (PBMCs) from subjects with HIES on stimulation with staphylococcal enterotoxin B (SEB) (Fig. 1a). The frequency of SEB-induced interferon (IFN)-γ-producing CD4 T cells from PBMCs of subjects with HIES was similar to that of healthy controls, whereas the frequency of cells producing IL-2 and/or tumour-necrosis factor (TNF) was slightly reduced. Fewer of the IFN-γ-producing CD4 T cells from subjects with HIES also produced TNF and/or IL-2 compared with healthy controls (Fig. 1b). IL-17-producing T cells were present in PBMCs from the HIES-like cohort with no mutations in stat3,suggesting that the lack of IL-17 production in HIES has a critical function in susceptibility to the specific infections seen in HIES, and also that elevated serum IgE, atopic dermatitis or low frequency of memory T cells (data not shown) are not independently associated with severe defects in the T H 17 axis (Fig. 1a). The production of IL-21 and IL-22, which have been described as both T H 1 and T H 17 cytokines9,10,18, was not significantly lower in subjects with HIES than in healthy controls. Additionally, among subjects with ...

Acute HIV infection is characterized by massive loss of CD4 T cells from the gastrointestinal (GI) tract. Th17 cells are critical in the defense against microbes, particularly at mucosal surfaces. Here we analyzed Th17 cells in the blood, GI tract, and broncheoalveolar lavage of HIV-infected and uninfected humans, and SIV-infected and uninfected sooty mangabeys. We found that (1) human Th17 cells are specific for extracellular bacterial and fungal antigens, but not common viral antigens; (2) Th17 cells are infected by HIV in vivo, but not preferentially so; (3) CD4 T cells in blood of HIV-infected patients are skewed away from a Th17 phenotype toward a Th1 phenotype with cellular maturation; (4) there is significant loss of Th17 cells in the GI tract of HIV-infected patients; (5) Th17 cells are not preferentially lost from the broncheoalveolar lavage of HIV-infected patients; and (6) SIV-infected sooty mangabeys maintain healthy frequencies of Th17 cells in the blood and GI tract. These observations further elucidate the immunodeficiency of HIV disease and may provide a mechanistic basis for the mucosal barrier breakdown that characterizes HIV infection. Finally, these data may help account for the nonprogressive nature of nonpathogenic SIV infection in sooty mangabeys.

The significance of elevated plasma levels of bacterial lipopolysaccharide (LPS) in persons with chronic HIV infection remains undefined. We measured LPS levels by use of limulus lysate assay, and DNA sequences encoding bacterial ribosomal 16S RNA (16S rDNA) were assessed by quantitative polymerase chain reactions in plasma samples obtained from 242 donors. Plasma levels of 16S rDNA were significantly higher in human immunodeficiency virus (HIV)–infected subjects than in uninfected subjects, and they correlated with LPS levels. Higher levels of 16S rDNA were associated with higher levels of T cell activation and with lower levels of CD4 T cell restoration during antiretroviral therapy. Antiretroviral therapy reduces but does not fully normalize plasma levels of bacterial 16S rDNA, an index of microbial translocation from the gastrointestinal tract. High levels of 16S rDNA during therapy are strongly associated with reduced increases in the CD4+ T lymphocyte count, irrespective of plasma HIV RNA levels. These findings are consistent with the importance of microbial translocation in immunodeficiency and T cell homeostasis in chronic HIV infection.

The mechanisms underlying the massive gastrointestinal tract CD4 T-cell depletion in human immunodeficiency virus (HIV) infection are not well understood nor is it clear whether similar depletion is manifest at other mucosal surfaces. Studies of T-cell and virus dynamics in different anatomical sites have begun to illuminate the pathogenesis of HIV-associated disease. Here, we studied depletion and HIV infection frequencies of CD4 T cells from the gastrointestinal tract, bronchoalveolar lavage (BAL), and blood with the frequencies and functional profiles of HIVspecific T cells in these anatomically distinct sites in HIV-infected individuals. The major findings to emerge were as follows: (i) depletion of gastrointestinal CD4 T cells is associated with high frequencies of infected CD4 T cells; (ii) HIV-specific T cells are present at low frequencies in the gastrointestinal tract compared to blood; (iii) BAL CD4 T cells are not massively depleted during the chronic phase; (iv) infection frequencies of BAL CD4 T cells are similar to those in blood; (v) significantly higher frequencies and increased functionality of HIV-specific T cells were observed in BAL compared to blood. Taken together, these data suggest mechanisms for mucosal CD4 Tcell depletion and interventions that might circumvent global depletion of mucosal CD4 T cells.