Safety and immunogenicity of a zoster vaccine in varicella-zoster virus seronegative and low-seropositive healthy adults.

OBJECTIVE: To evaluate immunogenicity and tolerability of a live attenuated zoster vaccine in varicella-zoster virus (VZV) seronegative or low-seropositive adults > or = 30 years of age. STUDY DESIGN: Double-blind, placebo-controlled, randomized, multicenter study. Subjects were enrolled in two stages by prescreened serostatus. Subjects with a low VZV antibody titer (< or = 5 gpELISA units/mL) were enrolled in Stage 1. Subjects with undetecable VZV antibodies and no safety issues identified during Stage 1 were enrolled in Stage 2. All enrolled subjects were randomized 4:1 to receive one dose (approximately 50,000 PFU) of zoster vaccine or placebo and were followed for safety for 42 days postvaccination. Primary objectives/hypotheses: (1) no vaccine-related serious adverse experiences (AE); (2) < or = 1 laboratory-confirmed varicella-like rash with > 50 lesions within 42 days postvaccination. SECONDARY OBJECTIVE: summarize the VZV antibody response postvaccination. RESULTS: Twenty-one subjects (age 27 to 69 years; median 34) enrolled (1148 prescreened); 18 (including 4 seronegative subjects) received vaccine and 3 (including 1 seronegative subject) received placebo. Twenty subjects completed the study; one subject withdrew for reasons unrelated to safety. No serious vaccine-related AE or laboratory-confirmed varicella-like rashes with > 50 lesions were reported. In the zoster vaccine group, all 4 of the initially seronegative subjects (age 32 to 36 years; median 33.5) seroconverted and 6 of the 13 (46.2%) initially seropositive subjects had a > or = 4-fold rise in VZV-specific antibody titer at 6 weeks postvaccination. CONCLUSIONS: The zoster vaccine appears to be immunogenic and generally well tolerated in healthy adults > or = 30 years of age, regardless of initial VZV antibody serostatus.

Regulatory CD4(+)CD25(+) T cells in tumors from patients with early-stage non-small cell lung cancer and late-stage ovarian cancer.

Immunosuppression may contribute to the progression of cancer. In this study we assessed the structural and functional status of T cells from tumor specimens obtained from patients with early stage non-small cell lung cancer and late-stage ovarian cancer. Although some groups have described structural alterations in the TCR in patients with other malignancies, we did not observe decreased expression of the CD3zeta subunit in the tumor-associated T cells. However, increased percentages of CD4(+)CD25(+) T cells were observed in the non-small cell lung cancer tumor-infiltrating lymphocytes and ovarian cancer tumor-associated lymphocytes. Furthermore, these CD4(+)CD25(+) T cells were found to secrete transforming growth factor-beta, consistent with the phenotype of regulatory T cells. Despite a generalized expression of lymphocyte activation markers in the tumor-associated T-cell populations, the CD8(+) T cells expressed low levels of CD25. To determine whether expression of CD25 could be restored on the CD8 cells, tumor-associated T cells were stimulated with anti-CD3 and anti-CD28 monoclonal antibodies. After stimulation, nearly all of the CD8 T cells expressed CD25. Furthermore, despite the low levels of interleukin 2, IFN-gamma, and tumor necrosis factor-alpha secretion by the tumor-associated and peripheral blood T cells at baseline, stimulation with anti-CD3 and anti-CD28 monoclonal antibodies significantly increased the fraction of cells producing these cytokines. Thus, tumor-associated T cells from patients with early and late-stage epithelial tumors contain increased proportions of CD4(+)CD25(+) T cells that secrete the immunosuppressive cytokine transforming growth factor-beta. Furthermore, our results are consistent with previous reports showing impaired expression of CD25 on CD8(+) T cells in cancer patients. Finally, increased lymphocyte costimulation provided by triggering the CD28 receptor is able to increase CD25 expression and cytokine secretion in tumor-associated T cells. These observations provide evidence for the contribution of regulatory T cells to immune dysfunction in cancer patients.

Efficient priming of protein antigen-specific human CD4(+) T cells by monocyte-derived dendritic cells.

Dendritic cells (DCs) have the unique ability to initiate an immune response in vivo by capturing antigens (Ags) in peripheral tissues and migrating to secondary lymphoid organs, where they sensitize naive CD4(+) T cells. To mimic this process in vitro, previous studies have shown that DCs directly isolated from peripheral blood can be used to elicit primary responses to neoantigens (neoAgs). In other studies, when monocyte-derived DCs have been utilized to sensitize total CD4(+) T cells in vitro, only secondary proliferation to neoAgs could be elicited. In the present study, the relative abilities of CD40 ligation, protein kinase C activation, and culture in tumor necrosis factor alpha (TNF-alpha) to induce functional and phenotypic maturation of human DCs from monocyte precursors were compared. Optimal TNF-alpha-induced maturation of DCs required a prolonged 4-day culture. It was then found that loading immature DCs with the neoAgs keyhole limpet hemocyanin or human immunodeficiency virus-1 p24 gag prior to TNF-alpha-induced maturation, rather than after maturation, was crucial to sensitize CD4(+) T cells to new Ags. This primary proliferation to neoAgs was initiated from the CD4(+) CD45RA(+) naive T-cell population. Finally, it was found that monocyte-derived DCs acquired the ability to secrete interleukin-12 p70, after contact with Ag-specific T cells. The ability to prime and expand Ag-specific CD4(+) T cells ex vivo to neoAgs in serum-free conditions has potential application for cellular vaccination and adoptive immunotherapy.

A role for CD40-CD40 ligand interactions in the generation of type 1 cytokine responses in human leprosy.

The interaction of CD40 ligand (CD40L) expressed by activated T cells with CD40 on macrophages has been shown to be a potent stimulus for the production of IL-12, an obligate signal for generation of Th1 cytokine responses. The expression and interaction of CD40 and CD40L were investigated in human infectious disease using leprosy as a model. CD40 and CD40L mRNA and surface protein expression were predominant in skin lesions of resistant tuberculoid patients compared with the highly susceptible lepromatous group. IL-12 release from PBMC of tuberculoid patients stimulated with Mycobacterium leprae was partially inhibited by mAbs to CD40 or CD40L, correlating with Ag-induced up-regulation of CD40L on T cells. Cognate recognition of M. leprae Ag by a T cell clone derived from a tuberculoid lesion in the context of monocyte APC resulted in CD40L-CD40-dependent production of IL-12. In contrast, M. leprae-induced IL-12 production by PBMC from lepromatous patients was not dependent on CD40L-CD40 ligation, nor was CD40L up-regulated by M. leprae. Furthermore, IL-10, a cytokine predominant in lepromatous lesions, blocked the IFN-gamma up-regulation of CD40 on monocytes. These data suggest that T cell activation in situ by M. leprae in tuberculoid leprosy leads to local up-regulation of CD40L, which stimulates CD40-dependent induction of IL-12 in monocytes. The CD40-CD40L interaction, which is not evident in lepromatous leprosy, probably participates in the cell-mediated immune response to microbial pathogens.

Modulation of susceptibility to HIV-1 infection by the cytotoxic T lymphocyte antigen 4 costimulatory molecule.

CD4 T cells activated in vitro by anti-CD3/28-coated beads are resistant to infection by CC chemokine receptor 5 (CCR5)-dependent HIV-1 isolates. In vivo, antigen-presenting cells (APCs) activate CD4 T cells in part by signaling through the T cell receptor and CD28, yet cells stimulated in this manner are susceptible to HIV-1 infection. We show that cytotoxic T lymphocyte antigen 4 (CTLA-4) engagement counteracts the CD28 antiviral effects, and that the ratio of CTLA-4 to CD28 engagement determines the susceptibility of HIV-1 infection. Furthermore, unopposed CTLA-4 signaling provided by CD28 blockade promotes vigorous HIV-1 replication, despite minimal T cell proliferation. Finally, CTLA-4 antibodies decrease the susceptibility of antigen-activated CD4 T cells to HIV, suggesting a potential approach to prevent or limit viral spread in HIV-1-infected individuals.

B7-1, but not CD28, is crucial for the maintenance of the CD4+ T cell responses in human leprosy.

We used human leprosy as a model to compare patterns of costimulatory molecule expression in respect to the clinical/immunologic spectrum of disease. We found that B7-1, B7-2, and CD28 transcripts dominated in tuberculoid leprosy patients, who have potent T cell responses to Mycobacterium leprae. In contrast, CTLA-4 was more strongly expressed in lesions from lepromatous patients, who manifest specific T cell anergy to the leprosy bacterium. T cell clones from tuberculoid lesions were CD4+CD28+ or CD4+CD28-, and T cell clones from lepromatous lesions were predominantly CD8+CD28-. The M. leprae-specific recall response of CD4+ T cell clones from tuberculoid lesions was blocked by anti-B7-1 mAb, but not by anti-B7-2 mAb or CTLA-Ig. However, anti-CD28 and anti-CTLA-4 mAbs did not block activation of clones from tuberculoid lesions, suggesting that B7-1 may utilize another costimulatory pathway. Peripheral blood T cell responses in the lepromatous form were strongly regulated by CD28 during T cell activation, in contrast to the tuberculoid form. Thus, B7-1 costimulation could play a role in maintaining a strong immune response to the pathogen.

Vaccine-induced neutralizing antibodies directed in part to the simian immunodeficiency virus (SIV) V2 domain were unable to protect rhesus monkeys from SIV experimental challenge.

The potential of the simian immunodeficiency virus (SIV) variable 2 (V2) domain as an effective region to boost SIV-neutralizing antibodies and to protect against live SIV challenge was tested in rhesus macaques. In this study, two rhesus macaques were primed with vaccinia virus recombinants expressing the surface glycoprotein gp140 of SIVmac and were given booster injections with the SIVmac V2 domain presented by a highly immunogenic carrier, the hepatitis B surface antigen (HBsAg). The two vaccinated macaques exhibited SIV-neutralizing antibodies after primer injections that were enhanced by the V2/HBsAg injections. Part of these SIV-neutralizing antibodies were directed specifically to the V2 region, as shown by neutralization-blocking experiments. However, despite having consistent SIV-neutralizing antibody titers, animals were not protected against homologous challenge with BK28, the molecular clone of SIVmac251. No SIV envelope-specific cellular cytotoxic response was detected throughout the immunization protocol, suggesting that neutralizing antibodies directed to SIV envelope gp140 and especially to the V2 domain were unable on their own to protect against SIV challenge. Furthermore, the vaccinees seemed to have higher viral loads than control animals after challenge, raising the question of whether neutralizing antibodies induced by vaccination and directed to the SIV envelope selected viral escape mutants, as shown previously in SIV-infected macaques. This mechanism is certainly worthy of intensive investigation and raises some concern for SIV envelope-targeted immunization.

Immunogenicity of hybrid hepatitis B surface antigen particles.

Hepatitis B surface antigen (HBsAg) produced by recombinant DNA technology is now widely and safely used worldwide for hepatitis B vaccination. We used the HBsAg particle as a carrier molecule for presentation of selected human immunodeficiency virus type 1 (HIV-1) determinants to the immune system. Immunization studies carried out in primates showed that the particles elicit HIV specific virus neutralizing antibodies as well as T cell proliferative responses to both pathogens. As an experimental approach to active immunotherapy for hepatitis B virus (HBV) chronic carriers, we evaluated the efficiency of such hybrid antigen to overcome B cell tolerance in HBV transgenic mice.

Recombinant hepatitis B surface antigen as a carrier of human immunodeficiency virus epitopes.

Eukaryotic cells transformed with a plasmid expression vector are able to synthesize and assemble HBsAg, a complex multimeric lipoprotein particle. Hybrid particles carrying HIV1 antigenic determinants were constructed and injected into monkeys. A complete immune response including neutralizing antibodies, proliferative and cytotoxic T-cell activities was obtained. Thus, such HIV/HBsAg hybrid particles could be a new approach to multivalent vaccination.

Human immunodeficiency virus type 1 major neutralizing determinant exposed on hepatitis B surface antigen particles is highly immunogenic in primates.

Hepatitis B surface antigen (HBsAg) produced by recombinant DNA technology is now widely and safely used worldwide for hepatitis B vaccination. We used the HBsAg particle as a carrier molecule for presentation of selected human immunodeficiency virus type 1 (HIV-1) determinants to the immune system. Immunization of rhesus monkeys with an HBsAg chimera carrying the HIV-1 envelope major neutralizing determinant allowed us to generate proliferative T-cell responses and, in some cases, neutralizing antibodies and antibody-dependent cellular cytotoxicity. Since there is an overlap between populations at risk for hepatitis B virus and HIV, HBsAg recombinant particles may be relevant carriers for HIV-1 epitopes and could offer a new approach to the development of an AIDS vaccine.