Immunization Of Human Volunteers Research Articles

Differential effect on cell-mediated immunity in human volunteers after intake of different lactobacilli

Probiotics are live microorganisms which have beneficial effects on the host when ingested in adequate amounts. Probiotic bacteria may stimulate immune effector functions in a strain-specific manner. In this blind placebo-controlled trial, we investigated the effects on the immune system following daily intake of six different strains of lactobacilli or the Gram-negative bacterium Pseudomonas lundensis for 2 or 5 weeks. Blood lymphocyte subsets were quantified by fluorescence activated cell sorter and the expression of activation and memory markers was determined. The bacterial strains were also examined for their capacity to adhere to human intestinal cells and to be phagocytosed by human peripheral blood mononuclear cells. Intake of Lactobacillus plantarum strain 299v increased the expression of the activation marker CD25 (P = 0·01) on CD8(+) T cells and the memory cell marker CD45RO on CD4(+) T cells (P = 0·03), whereas intake of L. paracasei tended to expand the natural killer T (NK T) cell population (P = 0·06). The phagocytic activity of granulocytes was increased following intake of L. plantarum 299v, L. plantarum HEAL, L. paracasei or L. fermentum. In contrast, ingestion of L. rhamnosus decreased the expression of CD25 and CD45RO significantly within the CD4(+) cell population. The observed immune effects after in-vivo administration of the probiotic bacteria could not be predicted by either their adherence capacity or the in-vitro-induced cytokine production. The stimulation of CD8(+) T cells and NK T cells suggests that intake of probiotic bacteria may enhance the immune defence against, e.g. viral infections or tumours.

Immunization of Human Volunteers With Hepatitis C Virus Envelope Glycoproteins Elicits Antibodies That Cross-Neutralize Heterologous Virus Strains

TO THE EDITOR—Ray and colleagues recently demonstrated hepatitis C virus (HCV) glycoprotein-specific neutralizing responses against homologous HCV-1 and the closely related genotype 1a HCV strain H77 [1]. Using well-characterized pseudoparticle (HCVpp) and cell culture replicating virus systems (HCVcc) [2], we set out to further investigate the breadth of the neutralizing responses elicited by vaccination. We tested serum samples from 8 of the volunteers reported in the study by Ray et al [1], selecting representative samples that had low, intermediate, and high anti-E1E2 antibody titers as measured by enzyme immunoassay (Novartis Vaccines and Diagnostics, Emeryville, CA). Generation of cross-reactive neutralizing antibodies (nAb) in response to vaccination has been a major hurdle for RNA viruses such as human immunodeficiency virus (reviewed in [3]). We reported that immunizing rodents with HCV E1E2 heterodimer or truncated soluble E2 derived from the genotype 1a HCV-1 strain elicited high titer cross-reactive nAb [2]. Here we report that immunization of healthy human volunteers with the same recombinant HCV-1 E1E2 glycoproteins can induce a cross-reactive neutralizing antibody response. Serum samples from 8 healthy immunized volunteers were assessed for their ability to neutralize a panel of HCVpp strains. Briefly, pre- and postimmune serum samples at a final dilution of 1/100 were preincubated with HCVpp encoding a luciferase reporter for 1 hour at 37°C prior to infecting Huh-7.5 cells for 6 hours at 37°C. Infection was quantified after 72 hours by monitoring luciferase activity (Figure 1). All immune serum samples neutralized HCVpp expressing the closely related genotype 1a H77 glycoproteins, the heterologous genotype 1b glycoproteins CON1 and OH8, and the more distantly related genotype 2a strain J6, albeit with reduced efficiency. Preimmune and postimmune serum samples had no effect on murine leukemia virus pseudoparticle infection (Figure 1). Figure 1. Recombinant hepatitis C virus type 1 (HCV-1) genotype 1a E1E2 glycoproteins elicit cross-neutralizing activity in vaccinated humans. Eight healthy adult volunteers were immunized with 4–100 μg of E1E2 with adjuvant MF59 at 0, 1, and 6 ... To ascertain the ability of immune serum samples to neutralize HCVcc, we tested the sensitivity of chimeric JFH-1 viruses expressing H77 and J6 structural proteins to inhibition by immune serum samples. All serum samples were clearly capable of neutralizing both heterologous HCVcc viruses, although less efficiently in the case of the 2a virus (Figure 1). Our experiments demonstrate that immunization of human volunteers with recombinant E1E2 glycoproteins derived from the genotype 1a strain elicits antibodies that can cross-neutralize the in vitro infectivity of heterologous strains derived from genotypes 1a, 1b, and 2a. Despite indications that HCV can transmit in vitro in the presence of antibodies targeting the viral encoded glycoproteins via direct transfer between adjacent contacting cells [4], recent studies with chimeric SCID-uPA mice have yielded encouraging results for a protective role of nAb to prevent or ameliorate virus infection in vivo [5, 6]. Our studies using HCVpp and matching HCVcc strains expand upon the work of Ray et al [1] and demonstrate that vaccination of human volunteers elicits antibody responses with significant cross-neutralizing activity against heterologous 1a, 1b, and 2a HCV genotypes, warranting the continued clinical development of recombinant glycoprotein vaccine preparations.

A New Recombinant Bacille Calmette‐Guérin Vaccine Safely Induces Significantly Enhanced Tuberculosis‐Specific Immunity in Human Volunteers

One strategy for improving anti-tuberculosis (TB) vaccination involves the use of recombinant bacille Calmette-Guérin (rBCG) overexpressing protective TB antigens. rBCG30, which overexpresses the Mycobacterium tuberculosis secreted antigen Ag85b, was the first rBCG shown to induce significantly greater protection against TB in animals than parental BCG. We report here the first double-blind phase 1 trial of rBCG30 in 35 adults randomized to receive either rBCG30 or parental Tice BCG intradermally. Clinical reactogenicity was assessed, and state-of-the-art immunological assays were used to study Ag85b-specific immune responses induced by both vaccines. Similar clinical reactogenicity occurred with both vaccines. rBCG30 induced significantly increased Ag85b-specific T cell lymphoproliferation, interferon (IFN)-gamma secretion, IFN-gamma enzyme-linked immunospot responses, and direct ex vivo intracellular IFN-gamma responses. Additional flow cytometry studies measuring carboxyfluorescein succinimidyl ester dilution and intracellular cytokine production demonstrated that rBCG30 significantly enhanced the population of Ag85b-specific CD4(+) and CD8(+) T cells capable of concurrent expansion and effector function. More importantly, rBCG30 significantly increased the number of Ag85b-specific T cells capable of inhibiting intracellular mycobacteria. These results provide proof of principal that rBCG can safely enhance human TB immunity and support further development of rBCG overexpressing Ag85b for TB vaccination.

Cutting edge: induction of follicular homing precedes effector Th cell development.

Transition from naive to Ag-experienced effector/memory CD4+ T cells is initiated during contact with APC in secondary lymphoid tissue. Here, we demonstrate that the CXCR5 is a marker for recently activated memory CD4+ T cells. CXCR5 is rapidly induced during contact with Ag-presenting dendritic cells, well before T cell expansion and effector cell development, and is irreversibly lost on terminally differentiated effector cells. Furthermore, immunization of human volunteers with a recall Ag results in rapid accumulation of Ag-responsive, CXCR5-expressing CD4+ T cells in peripheral blood. Early acquisition of a new migration program enables T zone CD4+ T cells to develop into follicular B helper T cells or, alternatively, into circulating memory CD4+ T cells. Together, CXCR5 unequivocally defines pre-effector memory CD4+ T cells generated during ongoing immune responses.

A randomized, double blind study in young healthy adults comparing cell mediated and humoral immune responses induced by influenza ISCOM™ vaccines and conventional vaccines

Although current influenza vaccines have been shown to reduce influenza-related morbidity and mortality, there is a desire to develop more efficacious products. Vaccines which can induce CD8 + cytotoxic T cell (CTL) responses in addition to strong antibody responses may be more effective in preventing disease since it has been demonstrated that CTL contribute to protective immunity, even against drift variants of influenza A viruses. The immunogenicity of two types of experimental influenza vaccines, which were based on immune stimulating complexes (ISCOM™), were evaluated and compared with a conventional non-adjuvanted inactivated split virion vaccine, after immunization of human volunteers. In this randomized, double blind study, it was shown that the ISCOM™ vaccines altered the kinetics of the serum antibody response, resulting in more rapid titer rises against the vaccine strains. This accelerated antibody response coincided with enhanced in vitro proliferative T cell responses, which were observed shortly after vaccination. In addition, CTL responses were observed in a higher proportion of the vaccinees receiving an ISCOM™ vaccine, than in vaccinees receiving the conventional influenza vaccine.

Erratum

Erratum

Calcitriol (1,25-dihydroxy-vitamin D3) coadministered with influenza vaccine does not enhance humoral immunity in human volunteers

Calcitriol, also known as 1,25-dihyrody-vitamin D3, is a steroid hormone that has been shown to have effects on cytokine production and lymphocyte proliferation. Coadministration of calcitriol with trivalent influenza vaccine in mice enhanced both mucosal and sytemic antibody responses. We studied the effects of calcitriol coadministered with a commercially available influenza vaccine in 175 human volunteers in this double-blind, placebo controlled clinical trial. Subjects that received calcitriol experienced more pain at the injection site compared with placebo recipients. No significant differences in hemagglutination inhibition titers against H1N1, H3N2, or influenza B antigens were detected at 1 or 3 months postvaccination. We conclude that coadministration of 1.0 μg of calcitriol at a site adjacent to influenza vaccination does not enhance humoral immunity in human volunteers.

Cutaneous reactions and antibody response to meningococcal group C polysaccharide vaccines in man.

In a recent report, the isolation and characterization of meningococcal polysaccharides of serogroups A, B, and C have been described [1]. Immunization of human volunteers with the purified polysaccharide of groups A and C meningococci resulted in the development of antibodies as measured by hemagglutination (HA) , bactericidal assay, and fluorescent antibody techniques [2, 3]. In these studies a dose of 50 ig was administered intracutaneously. Local skin reactions occurred in all recipients of vaccine, but these were minimal and disappeared within 48 hr. No systemic reactions were observed. The current studies were undertaken with the

Detection of Coproantibody and its Formation after Parenteral and Oral Immunization of Human Volunteers*

Antibodies in intestinal fluids or in feces were termed coproantibodies by Burrows and coworkers (1947). These antibodies have been demonstrated by many investigators (Davies, 1922; Torikata and Imaizumi, 1938; Predpechensky and Moroz, 1940; Skochko, 1942; Yampolski et al, 1944; Burrows et al, 1947; Burrows and Havens, 1948; Harrison and Banvard, 1947; Goodlow and Rittenberg, 1949; Gordon et al, 1950; Koshland and Burrows, 1950; Misonon, 1950; Barksdale and Ghoda, 1951a, b; Ghoda, 1952; Koshland, 1953; Mitchison, 1953; Kasai, 1954, 1957; Cooper, 1959; Steigman and Lipton, 1959; Basu Mallik and Roy, 1960). Early workers were concerned with fecal antibodies solely as diagnostic tools. In studies dating back to the first decade of this century, Besredka developed a concept of local immunity which stimulated a large amount of work on oral vaccination to enteric in-

INFLUENZA VIRUS B: II. IMMUNIZATION OF HUMAN VOLUNTEERS WITH LIVING ATTENUATED VIRUS

INFLUENZA VIRUS B: II. IMMUNIZATION OF HUMAN VOLUNTEERS WITH LIVING ATTENUATED VIRUS