Innate recognition of bacteria in human milk is mediated by a milk-derived highly expressed pattern recognition receptor, soluble CD14.

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Human cytomegalovirus pp65- and immediate early 1 antigen-specific HLA class I-restricted cytotoxic T cell responses induced by cross-presentation of viral antigens

Dendritic cells (DCs) play a pivotal role in the development of anti-viral CD8+ CTL responses. This is straightforward if they are directly infected with virus, but is less clear in response to viruses that cannot productively infect DCs. Human CMV (HCMV) shows strain-specific cell tropism: fibroblast (Fb)-adapted laboratory strains (AD169) and recent clinical isolates do not infect DCs, whereas endothelial cell-adapted strains (TB40/E) result in productive lytic DC infection. However, we show here that uninfected DCs induce CD8+ T cell cytotoxicity and IFN- production against HCMV pp65 and immediate early 1 Ags following in vitro coculture with HCMV-AD169-infected Fbs, regardless of the HLA type of these Fbs. CD8+ T cell stimulation was inhibited by pretreatment of DCs with cytochalasin B or brefeldin A, indicating a phagosome/endosome to cytosol pathway. HCMV-infected Fbs were not apoptotic as measured by annexin V binding, and induction of apoptosis of infected Fbs in vitro did not augment CTL induction by DCs, suggesting a mechanism other than apoptosis in the initiation of cross-presentation. Furthermore, HCMV-infected Fbs provided a maturation signal for immature DCs during coculture, as evidenced by increased CD83 and HLA class II expression. Cross-presentation of HCMV Ags by host DCs enables these professional APCs to bypass some of the evasion mechanisms HCMV has developed to avoid T cell recognition. It may also serve to explain the presence of immediate early 1 Ag-specific CTLs in the face of pp65-induced inhibition of Ag presentation at the level of the infected cell

Human Cytomegalovirus pp65- and Immediate Early 1 Antigen-Specific HLA Class I-Restricted Cytotoxic T Cell Responses Induced by Cross-Presentation of Viral Antigens

Dendritic cells (DCs) play a pivotal role in the development of anti-viral CD8+ CTL responses. This is straightforward if they are directly infected with virus, but is less clear in response to viruses that cannot productively infect DCs. Human CMV (HCMV) shows strain-specific cell tropism: fibroblast (Fb)-adapted laboratory strains (AD169) and recent clinical isolates do not infect DCs, whereas endothelial cell-adapted strains (TB40/E) result in productive lytic DC infection. However, we show here that uninfected DCs induce CD8+ T cell cytotoxicity and IFN- production against HCMV pp65 and immediate early 1 Ags following in vitro coculture with HCMV-AD169-infected Fbs, regardless of the HLA type of these Fbs. CD8+ T cell stimulation was inhibited by pretreatment of DCs with cytochalasin B or brefeldin A, indicating a phagosome/endosome to cytosol pathway. HCMV-infected Fbs were not apoptotic as measured by annexin V binding, and induction of apoptosis of infected Fbs in vitro did not augment CTL induction by DCs, suggesting a mechanism other than apoptosis in the initiation of cross-presentation. Furthermore, HCMV-infected Fbs provided a maturation signal for immature DCs during coculture, as evidenced by increased CD83 and HLA class II expression. Cross-presentation of HCMV Ags by host DCs enables these professional APCs to bypass some of the evasion mechanisms HCMV has developed to avoid T cell recognition. It may also serve to explain the presence of immediate early 1 Ag-specific CTLs in the face of pp65-induced inhibition of Ag presentation at the level of the infected cell

Human cytomegalovirus inhibits maturation and impairs function of monocyte-derived dendritic cells

Dendritic cells (DCs) play a pivotal role in the generation of virus-specific cytotoxic T-cell responses, but some viruses can render DCs inefficient in stimulating T cells. We studied whether infection of DCs with human cytomegalovirus (HCMV) results in a suppression of DC function which may assist HCMV in establishing persistence. The effect of HCMV infection on the phenotype and function of monocyte-derived DCs and on their ability to mature following infection with an endothelial cell-adapted clinical HCMV isolate were studied. HCMV infection induced no maturation of DCs; instead, it efficiently down-regulated the expression of surface major histocompatibility complex (MHC) class I, CD40, and CD80 molecules. Slight down-regulation of MHC class II and CD86 molecules was also observed. Lipopolysaccharide (LPS)-induced maturation of infected DCs was strongly inhibited, as indicated by lower levels of surface expression of MHC class I, class II, costimulatory, and CD83 molecules. The down-regulation or inhibition of these surface markers occurred only in HCMV antigen-positive DCs. DCs produced no interleukin 12 (IL-12) and only low levels of tumor necrosis factor alpha (TNF-) upon HCMV infection. Furthermore, cytokine production upon stimulation with LPS or CD40L was significantly impaired. Inhibition of cytokine production did not depend on viral gene expression as UV-irradiated HCMV resulted in the same effect. Proliferation and cytotoxicity of T cells specific to a recall antigen presented by DCs were also reduced when DCs were HCMV infected. This study shows that HCMV inhibits DC function, revealing a powerful viral strategy to delay or prevent the generation of virus-specific cytotoxic T cells

Influenza A antigen exposure selects dominant Vbeta17+ TCR in human CD8+ cytotoxic T cell responses

During acute human viral infections, such as influenza A, specific cytotoxic T lymphocytes (CTL) are generated which aid virus clearance. We have observed that in HLA-A*0201+ subjects, CTL expressing Vβ17+ TCR and recognizing a peptide from the influenza A matrix protein (M158–66) dominate this response. In experimental models of infection such dominance can be due to inheritance of a restricted T cell repertoire or acquired consequent on expansion of CTL bearing an optimum TCR conformation against the MHC–peptide complex. To examine how influenza A infection might influence the development of TCR V0β17 expansion, we studied influenza A-specific CTL in a cross-sectional study of 82 HLA-A*0201+ individuals from birth (cord blood) to adulthood. Primary M158–66 -specific CTL were detected in cord blood, but their TCR were diverse and depletion of Vβ17+ cells did not abrogate specific cytotoxicity. In contrast following natural influenza A infection, TCR Vβ17+ CTL dominated to the extent that only one of nine adult CTL lines retained any functional activity after in vitro depletion of Vβ17+ CTL. These results suggest that the dominance of Vβ17+ TCR among adult M158–66-specific CTL results from maturation and focussing of the response driven by exposure to influenza, and have implications for optimum immunization strategies

Clinical studies of human papilloma vaccines in cervical cancer

Cervical cancer is the second most common cause of cancer death world wide’ and is a particular problem in developing countries. Even with optimum treatment approximately 40% continue to die from this disease.2There is therefore a need for new strategies to reduce global mortality, including immunotherapeutic intervention