Evaluation of tolerability and antibody response after recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and a single dose of recombinant hepatitis B vaccine

Vaccines as treatments for prostate cancer

Prostate cancer is a leading cause of death in men worldwide. For over 30 years, growing interest has focused on the development of vaccines as treatments for prostate cancer, with the goal of using vaccines to activate immune cells capable of targeting prostate cancer to either eradicate recurrent disease or at least delay disease progression. This interest has been prompted by the prevalence and long natural history of the disease and by the fact that the prostate is an expendable organ. Thus, an immune response elicited by vaccination might not need to target the tumour uniquely but could theoretically target any prostate tissue. To date, different vaccine approaches and targets for prostate cancer have been evaluated in clinical trials. Overall, five approaches have been assessed in randomized phase III trials and sipuleucel-T was approved as a treatment for metastatic castration-resistant prostate cancer, being the only vaccine approved to date by the FDA as a treatment for cancer. Most vaccine approaches showed safety and some evidence of immunological activity but had poor clinical activity when used as monotherapies. However, increased activity has been observed when these vaccines were used in combination with other immune-modulating therapies. This evidence suggests that, in the future, prostate cancer vaccines might be used to activate and expand tumour-specific T cells as part of combination approaches with agents that target tumour-associated immune mechanisms of resistance.

Development and evaluation of a recombinant VP2 neutralizing epitope antigen vaccine candidate for infectious bursal disease virus

Infectious bursal disease (IBD) is one of the most economically important infectious diseases. Currently, vaccination is the most effective method to prevent IBD. Medium-virulence vaccines can damage the bursa of Fabricius and result in immunosuppression. Therefore, it is essential to develop a safe and effective vaccine against infectious bursal disease virus (IBDV). In this study, the five neutralizing epitopes of the IBDV VP2 protein were confirmed by neutralizing single chain variable fragment antibodies. Then, the neutralizing epitopes antigen (NEA) protein was constructed with five neutralizing epitopes and expressed by pET-27b. Furthermore, the immune effect and protective immunity of the NEA protein with the following adjuvants were evaluated in specific-pathogen-free chickens: oil emulsion adjuvant (OEA), double emulsion adjuvant (DEA), granulocyte-macrophage colony-stimulating factor (GM-CSF) adjuvant and complete Freund's adjuvant (CFA). The experimental results demonstrated that chickens immunized with NEA vaccines elicited stronger humoral and/or cellular immune responses and inflammatory responses than those in the NEA protein group. Chickens were protected in OEA, CFA and GM-CSF adjuvant groups, which were challenged with virulent IBDV BC6/85. Furthermore, IBDV RNA was not measured, and there appeared to be little apoptosis in the bursa of Fabricius based on TUNEL histology and the expression of Bax and Bcl-2 in the OEA, CFA and GM-CSF adjuvant groups. Based on the experimental results, the advantages and disadvantages of adjuvants and industrial production methods, GM-CSF was found to be the optimal adjuvant. Therefore, NEA with GM-CSF adjuvant is a promising vaccine candidate against IBDV, and it provides a framework for developing other vaccines against infectious viral diseases.

Multicenter Phase I Trial of a DNA Vaccine Encoding the Androgen Receptor Ligand-binding Domain (pTVG-AR, MVI-118) in Patients with Metastatic Prostate Cancer

PURPOSE

Preclinical studies demonstrated that a DNA vaccine (pTVG-AR, MVI-118) encoding the androgen receptor ligand-binding domain (AR LBD) augmented antigen-specific CD8⁺ T cells, delayed prostate cancer progression and emergence of castration-resistant disease, and prolonged survival of tumor-bearing mice. This vaccine was evaluated in a multicenter phase I trial.

PATIENTS AND METHODS

Patients with metastatic castration-sensitive prostate cancer (mCSPC) who had recently begun androgen deprivation therapy were randomly assigned to receive pTVG-AR on one of two treatment schedules over one year, and with or without GM-CSF as a vaccine adjuvant. Patients were followed for 18 months. Primary objectives were safety and immune response. Secondary objectives included median time to PSA progression, and 18-month PSA-PFS (PPFS).

RESULTS

Forty patients were enrolled at three centers. Twenty-seven patients completed treatment and 18 months of follow-up. Eleven patients (28%) had a PSA progression event before the 18-month time point. No grade 3 or 4 adverse events were observed. Of 30 patients with samples available for immune analysis, 14 (47%) developed Th1-type immunity to the AR LBD, as determined by IFNγ and/or granzyme B ELISPOT. Persistent IFNγ immune responses were observed irrespective of GM-CSF adjuvant. Patients who developed T-cell immunity had a significantly prolonged PPFS compared with patients without immunity (HR = 0.01; 95% CI, 0.0-0.21; P = 0.003).

CONCLUSIONS

pTVG-AR was safe and immunologically active in patients with mCSPC. Association between immunity and PPFS suggests that treatment may delay the time to castration resistance, consistent with preclinical findings, and will be prospectively evaluated in future trials.See related commentary by Shenderov and Antonarakis, p. 5056.

Co-administration of GM-CSF expressing RNA is a powerful tool to enhance potency of SAM-based vaccines

Self-amplifying mRNAs (SAM)-based vaccines have been shown to induce a robust immune response in various animal species against both viral and bacterial pathogens. Due to their synthetic nature and to the versatility of the manufacturing process, SAM technology may represent an attractive solution for rapidly producing novel vaccines, which is particularly critical in case of pandemic infections or diseases mediated by newly emerging pathogens. Recent published data support the hypothesis that Antigen Presenting Cells (APCs) are responsible for CD8+ T-cell priming after SAM vaccination, suggesting cross-priming as the key mechanism for antigen presentation by SAM vaccines. In our study we investigated the possibility to enhance the immune response induced in mice by a single immunization with SAM by increasing the recruitment of APCs at the site of injection. To enhance SAM immunogenicity, we selected murine granulocyte-macrophage colony-stimulating factor (GM-CSF) as a model chemoattractant for APCs, and developed a SAM-GM-CSF vector. We evaluated whether the use of SAM-GM-CSF in combination with a SAM construct encoding the Influenza A virus nucleoprotein (NP) would lead to an increase of APC recruitment and NP-specific immune response. We indeed observed that the administration of SAM-GM-CSF enhances the recruitment of APCs at the injection site. Consistently with our hypothesis, co-administration of SAM-GM-CSF with SAM-NP significantly improved the magnitude of NP-specific CD8+ T-cell response both in terms of frequency of cytotoxic antigen-specific CD8+ T-cells and their functional activity in vivo. Furthermore, co-immunization with SAM-GM-CSF and SAM-NP provided an increase in protection against a lethal challenge with influenza virus. In conclusion, we demonstrated that increased recruitment of APCs at the site of injection is associated with an enhanced effectiveness of SAM vaccination and might be a powerful tool to potentiate the efficacy of RNA vaccination.

Modular MLV-VLPs co-displaying ovalbumin peptides and GM-CSF effectively induce expansion of CD11b+ APC and antigen-specific T cell responses in vitro

The development of novel vaccination strategies is a persistent challenge to provide effective prophylactic treatments to encounter viral infections. In general, the physical conjugation of selected vaccine components, e.g. antigen and adjuvant, has been shown to enhance the immunogenicity and hence, can increase effectiveness of the vaccine. In our proof-of-concept study, we generated non-infectious, replication deficient Murine Leukemia Virus (MLV)-derived virus-like particles (VLPs) that physically link antigen and adjuvant in a modular fashion by co-displaying them on their surface. For this purpose, we selected the immunodominant peptides of the model antigen ovalbumin (OVA) and the cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) as non-classical adjuvant. Our results show that murine GM-CSF displayed on MLV-VLPs mediates expansion and proliferation of CD11b⁺ cells within murine bone marrow and total spleen cells. Moreover, we show increased immunogenicity of modular VLPs co-displaying OVA peptides and GM-CSF by their elevated capacity to induce OVA-specific T cell-activation and -proliferation within OT-I and OT-II splenocyte cultures. These enhanced effects were not achieved by using an equimolar mixture of VLPs displaying either OVA or GM-CSF. Taken together, OVA and GM-CSF co-displaying MLV-VLPs are able to target and expand antigen presenting cells which in turn results in enhanced antigen-specific T cell activation and proliferation in vitro. These data suggest MLV-VLPs to be an attractive platform to flexibly combine antigen and adjuvant for novel modular vaccination approaches.

Current concepts on immunopathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) infection is a leading cause of liver damage and hepatic inflammation. Upon infection, effective antiviral responses by CD8+ T cells, CD4+ T cells, Natural killer (NK) cells, and monocytes can lead to partial or complete eradication of the viral infection. To date, many studies have shown that the production of inhibitory cytokines such as Interleukin 10 (IL-10), Transforming growth factor beta (TGF-β), along with dysfunction of the dendritic cells (DCs), and the absence of efficient innate immune responses could lead to T cell exhaustion, development of persistent infection, and inability to eradicate the viral infection from liver. Understanding the immunopathogenesis of the virus could be useful in providing further insights toward novel strategies in the eradication of HBV infection.

Cytokine-Mediated Immunopathogenesis of Hepatitis B Virus Infections

Hepatitis B virus (HBV) infection is a worldwide health problem, with approximately one third of populations have been infected, among which 3-5% of adults and more than 90% of children developed to chronic HBV infection. Host immune factors play essential roles in the outcome of HBV infection. Thus, ineffective immune response against HBV may result in persistent virus replications and liver necroinflammations, then lead to chronic HBV infection, liver cirrhosis, and even hepatocellular carcinoma. Cytokine balance was shown to be an important immune characteristic in the development and progression of hepatitis B, as well as in an effective antiviral immunity. Large numbers of cytokines are not only involved in the initiation and regulation of immune responses but also contributing directly or indirectly to the inhibition of virus replication. Besides, cytokines initiate downstream signaling pathway activities by binding to specific receptors expressed on the target cells and play important roles in the responses against viral infections and, therefore, might affect susceptibility to HBV and/or the natural course of the infection. Since cytokines are the primary causes of inflammation and mediates liver injury after HBV infection, we have discussed recent advances on the roles of various cytokines [including T helper type 1 cells (Th1), Th2, Th17, regulatory T cells (Treg)-related cytokines] in different phases of HBV infection and cytokine-related mechanisms for impaired viral control and liver damage during HBV infection. We then focus on experimental therapeutic applications of cytokines to gain a better understanding of this newly emerging aspect of disease pathogenesis.

Effect of GM-CSF in combination with hepatitis B vaccine on revacination of healthy adult non-responders

OBJECTIVE

To assess the immune effects and safety of using GM-CSF with the yeast-recombinant hepatitis B virus (HBV) vaccine for the re-vaccination of healthy adults who did not respond to a previous vaccination.

METHODS

Study participants included 1784 healthy adults and 100 individuals diagnosed as non-responders. These healthy non-responders were randomly assigned to one of the three treatment groups: Group A (34 individuals) was given 150 microg of granulocyte-macrophage colony stimulating factor (GM-CSF) the first day, then 20 microg of the vaccine; Group B (33 individuals) was given 40 microg of the vaccine only; and, group C (33 individuals) was injected with 20 microg of vaccine each time. All participants were injected three times, at time of study enrollment and one and six months later. Anti-HB surface antigen (HBs) antibody titers were tested before treatment and at one (T1), two (T2) and eight (T8) months post-first injection.

RESULTS

At T1, the rate of anti-HBs antibody(+) in groups A, B and C was 26.47%, 48.48% and 18.18%, respectively (p = .027). At T8, the seropositive rate of group A (64.71%) and group B (75.76%) was significantly higher than in group C (39.39%) (p = .011); the geometric mean of the antibody titer for groups A and B was higher than for group C (p = .0173). All three treatments were safe and well-tolerated.

CONCLUSIONS

Augmentation of the vaccine dose and co-administration of GM-CSF and the standard vaccine dose are effective for HBV vaccine non-responders. In fact, changing the vaccine dose had a better seropositive response than injecting the vaccine in combination with GM-CSF.

Chitosan solution enhances the immunoadjuvant properties of GM-CSF

Sustained, local delivery of immunomodulatory cytokines is under investigation for its ability to enhance vaccine and anti-tumor responses both clinically and preclinically. This study evaluates the ability of chitosan, a biocompatible polysaccharide, to (1) control the dissemination of a cytokine, GM-CSF, and (2) enhance the immunoadjuvant properties of GM-CSF. While cytokines have previously been delivered in lipid-based adjuvants and other vehicles, these do not have the clinical safety profile or unique properties of chitosan. We found that chitosan solution maintained a measurable depot of recombinant GM-CSF (rGM-CSF) at a subcutaneous injection site for up to 9 days. In contrast, when delivered in a saline vehicle, rGM-CSF was undetectable in 12-24h. Furthermore, a single s.c. injection of 20 microg rGM-CSF in chitosan solution (chitosan/rGM-CSF(20 microg)) transiently expanded lymph nodes up to 4.6-fold and increased the number of MHC class II expressing cells and dendritic cells by 7.4-fold and 6.8-fold, respectively. These increases were significantly greater than those measured when rGM-CSF was administered in saline at the standard preclinical dose and schedule, i.e. 4 daily s.c. injections of 20 microg. Furthermore, lymph node cells from mice injected with chitosan/rGM-CSF(20 microg) induced greater allogeneic T cell proliferation, indicating enhanced antigen presenting capability, than lymph node cells from mice injected with rGM-CSF alone. Finally, in vaccination experiments, chitosan/rGM-CSF was superior to either chitosan or rGM-CSF alone in enhancing the induction of antigen-specific CD4(+) proliferation, peptide-specific CD8(+) pentamer staining and cytotoxic T cell lysis. Altogether, chitosan/rGM-CSF outperformed standard rGM-CSF administrations in dendritic cell recruitment, antigen presentation and vaccine enhancement. We conclude that chitosan solution is a promising delivery platform for the sustained, local delivery of rGM-CSF.

Use of granulocyte-macrophage colony-stimulating factor to reverse anergy in otherwise immunologically healthy children

BACKGROUND

T-cell anergy, as measured by delayed hypersensitivity skin testing, is associated with increased susceptibility to infection. Because the repertoire of effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) includes enhancement of antigen processing and presentation by antigen-presenting cells, GM-CSF has been used to augment immune function in human immunodeficiency virus-induced and other viral illness-induced immune dysfunction and to affect positively immune function in a wide variety of disorders.

OBJECTIVE

To attempt reversal of T-cell anergy using GM-CSF in 3 otherwise immunologically healthy children with severe recurrent and persistent viral respiratory tract infections and in one child with recurrent bacterial sepsis.

METHODS

After written informed consent and baseline data were obtained, the study participants were administered 3 two-week cycles of GM-CSF. Delayed hypersensitivity skin testing and laboratory tests were repeated 2 weeks after the third cycle and subsequently as clinically indicated.

RESULTS

All 4 children developed delayed hypersensitivity by skin testing, and all demonstrated markedly decreased number and severity of infection. Improvement persisted in all patients for at least 1 year. A single cycle of additional treatment in 2 patients reestablished delayed hypersensitivity and decreased infection, both of which persisted throughout the follow-up period of 4 or more years.

CONCLUSIONS

GM-CSF treatment reversed T-cell anergy in 4 children. Reestablishment of delayed hypersensitivity was associated with a significant decrease in infection. Although further studies will be needed, use of GM-CSF should be considered as an immune modulator in patients with T-cell anergy and recurrent infections.

Granulocyte macrophage colony-stimulating factor as an adjuvant for hepatitis B vaccination: A meta-analysis

The efficacy of granulocyte macrophage colony-stimulating factor (GM-CSF) to enhance the immune response to hepatitis B virus vaccine has been object of several reports. We searched for randomized controlled clinical trials comparing GM-CSF given concomitantly to hepatitis B virus vaccine to vaccine given alone or with placebo. Data on rates of seroconversion (anti-HBs titers >10 IU/ml) from 13 studies (734 subjects) produced combined estimates that favored GM-CSF as compared to controls: rate ratio after a single immunization was 1.54 [95% confidence interval (CI), 1.04-2.27] and 1.20 (95% CI, 1.02-1.42) at the end of the vaccination cycle. Using a logistic approach a significant dose/response effect of GM-CSF was seen. Moreover, in renal failure patients who have responded to the vaccine, GM-CSF increased anti-HBs titers. Our findings suggest that GM-CSF induced a significant effect in terms of response rate and achievement of an earlier seroconversion to the vaccine in the overall populations examined, in renal failure patients and in healthy individuals.

Incorporation of glycosylphosphatidylinositol-anchored granulocyte- macrophage colony-stimulating factor or CD40 ligand enhances immunogenicity of chimeric simian immunodeficiency virus-like particles

The rapid worldwide spread of human immunodeficiency virus (HIV) mandates the development of successful vaccination strategies. Since live attenuated HIV is not accepted as a vaccine due to safety concerns, virus-like particles (VLPs) offer an attractive safe alternative because they lack the viral genome yet they are perceived by the immune system as a virus particle. We hypothesized that adding immunostimulatory signals to VLPs would enhance their efficacy. To accomplish this we generated chimeric simian immunodeficiency virus (SIV) VLPs containing either glycosylphosphatidylinositol (GPI)-anchored granulocyte-macrophage colony-stimulating factor (GM-CSF) or CD40 ligand (CD40L) and investigated their biological activity and ability to enhance immune responses in vivo. Immunization of mice with chimeric SIV VLPs containing GM-CSF induced SIV Env-specific antibodies as well as neutralizing activity at significantly higher levels than those induced by standard SIV VLPs, SIV VLPs containing CD40L, or standard VLPs mixed with soluble GM-CSF. In addition, mice immunized with chimeric SIV VLPs containing either GM-CSF or CD40L showed significantly increased CD4(+)- and CD8(+)-T-cell responses to SIV Env, compared to standard SIV VLPs. Taken together, these results demonstrate that the incorporation of immunostimulatory molecules enhances humoral and cellular immune responses. We propose that anchoring immunostimulatory molecules into SIV VLPs can be a promising approach to augmenting the efficacy of VLP antigens.

Meta-analysis: the adjuvant role of granulocyte macrophage-colony stimulating factor on immunological response to hepatitis B virus vaccine in end-stage renal disease

BACKGROUND

Chronic dialysis patients often fail to produce protective antibodies to hepatitis B virus surface antigen after vaccination towards hepatitis B virus (HBV). Several authors suggested a benefit for granulocyte macrophage-colony stimulating factor (GM-CSF) as an adjuvant to HBV vaccination in patients with end-stage renal disease (ESRD). However, consistent information is still lacking.

AIMS

To evaluate efficacy and safety of GM-CSF as adjuvant to hepatitis B vaccine in patients with ESRD by performing a systematic review with a meta-analysis of prospective controlled clinical trials (CCTs).

METHODS

Only trials comparing the seroresponse rate in study (GM-CSF plus HBV vaccine) versus control (HBV vaccine alone) patients were included. We used the random effects model of DerSimonian and Laird, with heterogeneity and sensitivity analyses. The end-point of interest was the rate of patients showing seroprotective anti-hepatitis B titers at completion of HBV vaccine schedule in study versus control groups.

RESULTS

We identified seven studies involving 187 unique patients with ESRD. Only prospective CCTs were included. Pooling of study results showed a significant increase in response rates among study (GM-CSF plus HBV vaccine) versus control (HBV vaccine alone) patients (pooled Odds Ratio, 4.63 [95% Confidence Intervals, 1.42; 15.14]). The P-value was 0.02 for our test of study heterogeneity.

CONCLUSIONS

Our meta-analysis showed improved seroprotection rates with HBV vaccine after GM-CSF administration.

Expression of CCL20 and granulocyte-macrophage colony-stimulating factor, but not Flt3-L, from modified vaccinia virus ankara enhances antiviral cellular and humoral immune responses

While modified vaccinia virus Ankara (MVA) is currently in clinical development as a safe vaccine against smallpox and heterologous infectious diseases, its immunogenicity is likely limited due to the inability of the virus to replicate productively in mammalian hosts. In light of recent data demonstrating that vaccinia viruses, including MVA, preferentially infect antigen-presenting cells (APCs) that play crucial roles in generating antiviral immunity, we hypothesized that expression of specific cytokines and chemokines that mediate APC recruitment and activation from recombinant MVA (rMVA) vectors would enhance the immunogenicity of these vectors. To test this hypothesis, we generated rMVAs that express murine granulocyte-macrophage colony-stimulating factor (mGM-CSF), human CCL20/human macrophage inflammatory protein 3alpha (hCCL20/hMIP-3alpha), or human fms-like tyrosine kinase 3 ligand (hFlt3-L), factors predicted to increase levels of dendritic cells (DCs), to recruit DCs to sites of immunization, or to promote maturation of DCs in vivo, respectively. These rMVAs also coexpress the well-characterized, immunodominant lymphocytic choriomeningitis virus nucleoprotein (NP) antigen that enabled sensitive and quantitative assessment of antigen-specific CD8(+) T-cell responses following immunization of BALB/c mice. Our results demonstrate that immunization of mice with rMVAs expressing mGM-CSF or hCCL20, but not hFlt3-L, results in two- to fourfold increases of cellular immune responses directed against vector-encoded antigens and 6- to 17-fold enhancements of MVA-specific antibody titers, compared to those responses elicited by nonadjuvanted rMVA. Of note, cytokine augmentation of cellular immune responses occurs when rMVAs are given as primary immunizations but not when they are used as booster immunizations, suggesting that these APC-modulating proteins, when used as poxvirus-encoded adjuvants, are more effective at stimulating naïve T-cell responses than in promoting recall of preexisting memory T-cell responses. Our results demonstrate that a strategy to express specific genetic adjuvants from rMVA vectors can be successfully applied to enhance the immunogenicity of MVA-based vaccines.

Multigene/Multisubtype HIV-1 Vaccine Induces Potent Cellular and Humoral Immune Responses by Needle-Free Intradermal Delivery

Gene vaccination encounters problems different from those of gene therapy since both a short half-life of the gene and a strong immune response to the gene product are desirable. We have evaluated a DNA vaccine consisting of seven plasmids encoding nine HIV-1 proteins. Using a needle-free delivery device, the Biojector, together with recombinant mouse GM-CSF, this vaccine induced strong gp160 Env- and p24 Gag-specific cellular and humoral immune responses in mice. The rGM-CSF was crucial for inducing both antibodies and antigen-specific CD8(+) T cell responses against both gp160 and p24. A GMP-produced lot of this vaccine, intended for human use, was delivered intradermally or intramuscularly into BALB/c mice at a GLP-accredited animal facility. This vaccine induced strong cellular responses independent of the route of immunization; moreover, no signs of toxicity were detected after histopathological examination of various tissues. Overall, the results indicate that the intradermal delivery of multigene/multisubtype HIV DNA in combination with recombinant GM-CSF is a safe and efficacious strategy for inducing high levels of specific CD8(+) T cells and unusually high titers of antibodies. This vaccine has been approved by the Swedish Medicinal Products Agency and is currently in a Phase I clinical trial.

Granulocyte-macrophage colony-stimulating factor as an immune-based therapy in HIV infection

The HIV/AIDS epidemic continues to spread despite more than 20 years of significant research and major advances in its treatment. The introduction of highly active antiretroviral therapy in recent years has significantly improved disease treatment with a dramatic impact in HIV/AIDS associated morbidity and mortality in countries which have access to this therapy. Despite these advances, such therapies are imperfect and other therapeutic modalities, including immune-based therapies, are being actively sought. Potential benefits of immune-based therapies include: 1) the improvement of HIV-specific immunity to enhance control of viral replication, 2) the improvement of other aspects of host immunity in order to prevent or delay the development of opportunistic infections and 3) the potential to purge virus from cellular reservoirs which are sustained despite the effects of potent antiretroviral therapy. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been studied as one of these immune-based therapies. Several randomized, controlled trials have demonstrated benefits of using GM-CSF as an adjunct to conventional anti-retroviral therapy, although such benefits have not been universally observed. Individual studies have shown that GM-CSF increases CD4+ T cells counts and may be associated with decreased plasma HIV RNA levels. There is limited evidence that GM-CSF may help prevent the emergence of antiretroviral drug resistant viruses and that it may decrease the risk of infection in advanced HIV disease. Despite its high costs and the need to be administered subcutaneously, encouraging results continue to emerge from further studies, suggesting that GM-CSF has the potential to become an effective agent in the treatment of HIV infection.

Comparative studies of Avipox-GM-CSF versus recombinant GM-CSF protein as immune adjuvants with different vaccine platforms

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent immune stimulant when administered with different vaccines. Optimal use of GM-CSF resides in its ability to act locally to stimulate the proliferation and maturation of professional antigen-presenting cells (APCs) (i.e., Langerhans' cells) at the injection site. GM-CSF was engineered into a replication-incompetent recombinant avian (fowlpox) virus (rF-GM-CSF) and a single subcutaneous injection resulted in a sustained enrichment of activated dendritic cells within the regional draining lymph nodes. Those changes were attributed to local GM-CSF production at the injection site by rF-GM-CSF-infected cells. Studies were carried out in which mice were administered different types of beta-galactosidase (beta-gal)-based vaccines--whole protein, peptide, recombinant poxviruses--and GM-CSF was administered either as a single injection of rF-GM-CSF or four daily bolus injections of the recombinant protein. The use of rF-GM-CSF either improved the immune adjuvant effect, as observed for poxvirus-based vaccines, or was equivalent to rGM-CSF, as observed with the beta-gal protein vaccine. It is important to note that with either the replication-competent (vaccinia) or replication-incompetent (fowlpox) vaccines expressing LacZ, strong CTL responses directed against beta-gal were induced only when rF-GM-CSF was used as the immune adjuvant. Engineering GM-CSF into a recombinant fowlpox virus offers an excellent vehicle for the delivery of this cytokine as an immune adjuvant with specific vaccine platforms. In particular, delivery of GM-CSF via the rF-GM-CSF construct would be preferred over bolus injections of rGM-CSF when used as an immune adjuvant with whole protein or recombinant poxvirus-based vaccines. The study underscores the importance of defining the appropriate delivery form of an immune adjuvant, such as GM-CSF, relative to the immunization strategy to maximize the host immune responses against a specific antigen.

Efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) as a vaccine adjuvant for hepatitis B virus in patients with HIV infection

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is a cytokine with a potential vaccine adjuvant activity. It is also known that human immunodeficiency virus (HIV) infected patients often show poor immunologic responses to immunization. We examined whether the use of GM-CSF could augment the immunologic response to recombinant vaccine against the hepatitis B virus (HBV) in 80 HIV infected patients (18-35 years old). They received a double dose (40 microg) of recombinant HBV vaccine IM at 0, 1 and 6 months and were randomized to receive either concurrent 20 microg of GM-CSF (n=40) or placebo IM (n=40) with the first vaccine dose. A significant increase in the seroconversion rate was observed after the second vaccine dose in the GM-CSF group (62% GM-CSF versus 30% control group P<0.0074). The average anti-HBs titers measured on days 28, 60 and 210 were 40.3; 366.5 and 644.8 milli-international units per milliliter (mIU/ml), respectively, in the GM-CSF group, and 62.4; 166.4 and 375.0 mIU/ml, respectively, in the control group, with significant differences at 60 and 210 days (P<0.01). There were no significant differences between CD4/CD8 cells, viral load, risk factors, age, sex and the serological responses to the HBV vaccine. This study suggests that GM-CSF increases the immunogenicity of recombinant HBV vaccine in HIV infected individuals.

Recommendations for immunizations in stem cell transplantation

Investigations over the past decade have documented that there is a decline in immunity to vaccine preventable diseases in many SCT recipients. The majority of immunization studies conducted in SCT recipients to date support the use of multi-dose regimens for most protein and polysaccharide-conjugate vaccine antigens. The consensus immunization schedule recommended by ACIP/IDSA/ASBMT provides guidance for centers to utilize available vaccines in their SCT populations. With the exception of pneumococcal disease, a schedule beginning at 12 months after SCT is reasonable given the low incidence of disease in HSCT recipients for most of the recommended vaccines and improved immune reconstitution in most recipients by one year post transplant. SCT recipients respond poorly to unconjugated pneumococcal polysaccharide vaccine and the development of polysaccharide-protein conjugate vaccines against S. pneumoniae holds promise to impact potentially on clinical disease in this population. In addition, the strategy of donor immunization may also be effective in eliciting early protective immune responses to vaccine antigens. Future challenges will be the development of safe and effective vaccines against the viral pathogens responsible for considerable morbidity and mortality after SCT.

Revaccination of healthy nonresponders with hepatitis B vaccine and prediction of seroprotection response

Sixty healthy nonresponders were randomized to receive intramuscular (IM) high dose hepatitis B virus (HBV) vaccine versus IM standard dose HBV vaccine plus granulocyte-macrophage colony-stimulating factor (GM-CSF) at 0-2 months. Antibody to hepatitis B surface antigen was measured 1 month after each dose and 3 months after the last dose. Two regimens were equivalent in eliciting seroprotection in nonresponders. Weight-height index (WHI) <39 and alanine transaminase (ALT) <39 mg/dl predicted which nonresponders would seroconvert. A three-dose regimen of standard dose HBV vaccine plus GM-CSF may be a useful for seroprotection of healthy nonresponders.

A randomized, placebo-controlled trial of subcutaneous administration of GM-CSF as a vaccine adjuvant: effect on cellular and humoral immune responses

Thirty healthy volunteers were randomly assigned to receive either a single subcutaneous injection of GM-CSF or placebo at the time of vaccination with tetanus and diptheria toxoid (Td), influenza and hepatitis A vaccines. Humoral response was measured by weekly serum samples assayed for antibodies to tetanus toxoid (TT), influenza and hepatitis A; while cellular response to TT was determined by measuring IL-2 expression in T-cells following in vitro exposure to TT antigen using a flow cytometric assay. It was hypothesized that (1). GM-CSF would augment immune response and (2). that the frequencies of TT responsive T-cells in the blood would predict humoral responses. The administration of subcutaneous GM-CSF as an adjuvant at the time of vaccination did not augment the antibody responses to influenza or hepatitis A in normal volunteers when compared to placebo. Subjects who received GM-CSF had statistically significant lower increases in anti-tetanus antibodies than placebo recipients. Immunization with TT resulted in an increase in the frequency of antigen responsive T-cells in the blood over time. The frequencies of TT responsive T-cells in baseline blood samples were correlated with baseline anti-tetanus antibody titers, but humoral and cellular responses were not correlated following vaccination. Recipients of GM-CSF did not develop significantly higher numbers of TT responsive T-cells after vaccination compared to recipients who received placebo.

Randomized trial of influenza vaccine with granulocyte-macrophage colony-stimulating factor or placebo in cancer patients

PURPOSE

To determine whether granulocyte-macrophage colony-stimulating factor (GM-CSF) would improve response to influenza vaccination in cancer patients.

PATIENTS AND METHODS

In a randomized, patient-blinded, placebo-controlled trial carried out in 1997 to 2000, 133 patients were stratified into five groups of treatment and disease. Single doses of standard split trivalent influenza vaccine and either placebo or 250 micro g of GM-CSF were administered at the same time. Hemagglutination inhibition assay titers were measured before and 4 weeks after vaccination.

RESULTS

Standard analyses, which define response as at least a four-fold increase in titers, detect no effect of GM-CSF for any of the three influenza subtypes in the trivalent vaccines (P >or=.12). Analysis that includes the magnitude of the change in titers and combines responses of the subtypes suggests that the placebo group had the greater response (P =.051), thus indicating that GM-CSF does not improve response. Ancillary analyses show that response declines both with increasing age and with higher initial titers. The fraction of patients with at least a four-fold increase in titers was 0.36 (95% confidence interval, 0.29 to 0.42)

CONCLUSION

A single 250- micro g dose of GM-CSF administered with the influenza vaccine does not improve response to vaccination. Response in cancer patients is low and declines as age and initial titer increase.

Immune responses to an inactive vaccine against American cutaneous leishmaniasis together with granulocyte-macrophage colony-stimulating factor

The immunological response in healthy subjects to a crude leishmania antigen vaccine (Leishvacin) plus rhGM-CSF without prior Montenegro (DTH) skin testing was evaluated. Fifty-six healthy volunteers received vaccine plus either placebo or rhGM-CSF at day 0, followed by either a vaccine booster or placebo at day 21. IFN-gamma and IL-5 levels were significantly enhanced by day 21. The adjuvant group had a higher percentage of individuals with a significant response to vaccination than the corresponding placebo group. Eighty-six percent of all volunteers were DTH-positive by day 42. Leishvacin is capable of sensitizing lymphocytes from individuals not previously exposed to leishmania antigen. Use of rhGM-CSF enhanced the immune response, indicating that it may improve immunological response to the vaccine.

Granulocyte macrophage colony stimulating factor (GM-CSF) induced sero-protection in end stage renal failure patients to hepatitis B in vaccine non-responders

Hepatitis B (HB) virus infection is a major health problem in dialysis dependent end stage renal failure (ESRF) patients. The sero-conversion rate after recombinant HB vaccine in ESRF patients is poor. Adjuvants like Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) have been found to improve response rate to vaccines. This study was conducted to evaluate the efficacy of GM-CSF as an adjuvant to HB vaccine in ESRF patients who were non-responders to the usual three double dose vaccinations (primary non-responders). Fifty consecutive HBsAg negative and anti-HBs negative ESRF patients on hemodialysis over thirty months were prospectively included (Jan. 96-June 98). All received 40 microg of recombinant HB vaccine at 0, 1, 2 month interval. Anti-HBs titres were subsequently tested after four weeks of the third dose. There were 19 (38%) primary non-responders (antiHBs negative). Twelve (Group I) of primary non-responders were given an additional dose of HB vaccine with 300 microg (5-6 microg/kg) of GM-CSF (Leucomax) and the remaining seven (Group II) received only an additional dose of HB vaccine. Anti-HBs was determined by Abbott's ELISA kit, and titre above 10 mIU/mL was considered as protective. In Group I, sero-protective titres were obtained in 11 out of 12 (91.6%) patients, whereas in Group II none of the patients achieved sero-protection (p < 0.001). The sero-conversion rate improved from initial 62% (31/50) to overall 84% (42/150) after the use of GM-CSF. There were no adverse events noted with the use of GM-CSF. At one year, 24 out of 32 (75%) who were sero-protected earlier continued to remain sero-protected. This study indicates that GM-CSF is a potent HB vaccine adjuvant for sero-conversion in primary non-responders.

Vaccines for transplant recipients

Immune dysregulation and immunosuppression regimens impact on the ability of transplant recipients to respond to immunizations. The distinct challenges of immunizations to benefit stem cell transplant recipients and solid organ transplant recipients are discussed separately. Recommended vaccines for stem cell transplant recipients and solid organ transplant candidates are suggested. New approaches to consider to enhance immune responses of transplant recipients are discussed.

Hepatitis B immunization of healthy elderly adults: relationship between naïve CD4+ T cells and primary immune response and evaluation of GM-CSF as an adjuvant

The efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) to enhance the primary immune response to hepatitis B vaccine was studied in healthy elderly with young volunteers included as controls in this double-blind, placebo-controlled trial of GM-CSF as an immune adjuvant. Naïve T-helper cells (CD4+CD45RA+) were determined at baseline. Forty-five healthy elderly (average age, 74 years) and 37 healthy young controls (average age, 28 years) were randomized. Hepatitis B vaccine was administered at 0, 1, and 6 months. GM-CSF as a single injection of either 80 microg or 250 microg with the first and second doses of hepatitis B vaccine. In this trial GM-CSF did not enhance antibody responses. However, the antibody responses were dramatically different between these two groups: 35/35 young developed a protective titer versus 19/45 elderly (P < 0.0001). In addition, the mean logarithm of anti-hepatitis B antibody level in the 35 young who completed the study was 3.17 (log mIU/ml) but only 2.21 in the 19 elderly responders (P < 0.0001). Naïve T-helper cells differed significantly between the two groups: the mean percentage of CD4+CD45RA+ T cells was 47.9% versus 35.0% (P < 0.0001) in the young and elderly volunteers respectively. Naïve T cells also differed significantly between elderly who did or did not respond to HBV (39.9% vs. 31.7%, P = 0.039). Using linear regression, age, and percent naive, CD4 T cells were determined to significantly influence the anti-hepatitis B antibody response, but sex and dose of GM-CSF did not. For a two-parameter model: logarithm of antibody titer = (-0.038 x age in years) + (0.031 x % naïve CD4T cells) + 2.68; adjusted r2 = 0.605 and P < 0.0001. However, age had a larger effect than naive CD4 T cells, i.e., in comparing young and elderly groups the log antibody titer decreased by 1.73 due to the increase in age but only 0.40 due to the decrease in naive CD4 T cells. Thus, there was a large effect of age that could not be explained by the quantitative change in the naïve T-helper cells.

Plasmid vaccine expressing granulocyte-macrophage colony-stimulating factor attracts infiltrates including immature dendritic cells into injected muscles

Plasmid-encoded GM-CSF (pGM-CSF) is an adjuvant for genetic vaccines; however, little is known about how pGM-CSF enhances immunogenicity. We now report that pGM-CSF injected into mouse muscle leads to a local infiltration of potential APCs. Infiltrates reached maximal size on days 3 to 5 after injection and appeared in several large discrete clusters within the muscle. Immunohistological studies in muscle sections from mice injected with pGM-CSF showed staining of cells with the macrophage markers CD11b, Mac-3, IA(d)/E(d) and to the granulocyte marker GR-1 from day 1 through day 14. Cells staining with the dendritic cell marker CD11c were detected only on days 3 to 5. Muscles injected with control plasmids did not stain for CD11c but did stain for CD11b, Mac-3, IA(d)/E(d), and GR-1. No staining was observed with the APC activation markers, B7.1 or CD40, or with markers for T or B cells. These findings are consistent with the infiltrating cells in the pGM-CSF-injected muscles being a mixture of neutrophils, macrophages, and immature dendritic cells and suggest that the i.m. APCs may be enhancing immune responses to coinjected plasmid Ags. This hypothesis is supported by data showing that 1) separation of injections with pGM-CSF and Ag-expressing plasmid into different sites did not enhance immune responses and 2) immune enhancement was associated with the presence of CD11c+ cells in the infiltrates. Thus, pGM-CSF enhancement may depend on APC recruitment to the i.m. site of injection.

Comparative studies of the effects of recombinant GM-CSF and GM-CSF administered via a poxvirus to enhance the concentration of antigen- presenting cells in regional lymph nodes

Repeated subcutaneous (s.c.) injections of recombinant granulocyte-macrophage colony-stimulating factor (recGM-CSF) for 4-5 days can enrich an immunization site with antigen-presenting cells (APC), which has been correlated with improved immune responses in experimental and clinical studies. A recombinant vaccinia virus encoding the GM-CSF gene (rV-GM-CSF) has been developed and can generate specific antitumour immunity in a whole tumour cell vaccine. In the present study, we examined whether rV-GM-CSF could produce and release GM-CSF locally which, in turn, might enrich a site of immunization for APC as previously shown for recGM-CSF. S.c. injection of rV-GM-CSF significantly (P<0.05) enhanced the percentage and overall number of APC, measured by class II expression levels, in the regional lymph nodes that drain the injection site. Dose- and temporal-dependent studies showed class II expression levels in the draining lymph nodes were maximally enhanced 5-7 days after a single injection of 10(7)plaque-forming units (pfu) of rV-GM-CSF. Flow cytometry revealed that the increase in class II expression resulted from (i) a higher class II expression level on CD19(+)B cells and (ii) an increase in the number of CD11c(+)/class II(+)professional APC within the draining lymph nodes. Moreover, isolation of lymph nodes from rV-GM-CSF-treated mice revealed their capacity to support higher levels of antigen-specific T cell proliferation and allospecific cytotoxic responses. A comparison between a single injection of rV-GM-CSF and a 4-day course of recGM-CSF revealed comparable changes in class II expression and functional T cell assays. GM-CSF can be delivered in a recombinant poxvirus, and the local production of the cytokine results in cellular and phenotypic changes that are similar to those of recGM-CSF. The ability to utilize rV-GM-CSF as a single inoculum may be more compatible with traditional immunization strategies.

Induction of a protection against S. mansoni with a MAP containing epitopes of Sm37-GAPDH and Sm10-DLC. Effect of coadsorption with GM-CSF on alum

Studies of anti-S. mansoni immunological responses in individuals living in endemic areas identified immunogens (Sm37-GAPDH and Sm10-DLC) with vaccine candidate properties. Analysis of the epitopes of these immunogens indicated that: (i) Sm37-5 is a major B-cell epitope of Sm37-GAPDH and the IgG antibody reactivity toward this determinant is associated with resistance to reinfection; (ii) Sm10-T is a T-cell epitope of the major T-cell immunogen Sm10-DLC. This led us to test a multiple antigen peptide (MAP) containing Sm37-5 and Sm10-T as an anti-schistosome vaccine. This MAP induced a significant protective immune response in mice when injected in Freund's adjuvant or coadsorbed with GM-CSF on aluminium hydroxide. In the latter case the physical link between the cytokine and the antigen via the coadsorption on alum was necessary to obtain a protective response. Results of the antibody response indicated that when the MAP and GM-CSF were coadsorbed on alum, the antibody response against the Sm10-T epitope located in the NH(2)-terminal position was significantly amplified up to 30% of the anti-Sm37-5 response.

Prevention of neonatal tolerance by a plasmid encoding granulocyte-macrophage colony stimulating factor

A plasmid DNA vaccine encoding the circumsporozoite protein of malaria (pCSP) induces protective immunity in adult mice but persistent tolerance when administered to neonates. In an effort to improve antigen presenting cell (APC) function in newborns, we co-administered pCSP with a plasmid encoding granulocyte-macrophage colony stimulating factor (pGMCSF). This combination of plasmids prevented the development of neonatal tolerance, instead eliciting a primary IgG anti-CSP immune response. Mice primed as neonates and boosted as adults mounted anamnestic responses characterized by high serum antibody titers, cytotoxic T-cell activity and antigen-specific interferon gamma (IFNgamma) production. Neonatal administration of pGMCSF accelerated the maturation of local dendritic cells, suggesting that APC function plays a key role in determining whether tolerance or immunity results from neonatal exposure to antigen.

Immunization With Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor as a Vaccine Adjuvant Elicits Both a Cellular and Humoral Response to Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF–specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF–specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF–specific immune responses.

Immunization With Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor as a Vaccine Adjuvant Elicits Both a Cellular and Humoral Response to Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF–specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF–specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF–specific immune responses.

A novel influenza subunit vaccine composed of liposome-encapsulated haemagglutinin/neuraminidase and IL-2 or GM-CSF. I. Vaccine characterization and efficacy studies in mice

The aim of this study was to improve the potency of the currently used influenza subunit vaccines, which are of relatively low efficiency in high-risk groups. Influenza A virus (Shangdong/9/93) haemagglutinin/neuraminidase (H3N2), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) were encapsulated, each separately or combined, in multilamellar vesicles composed of dimyristoyl phosphatidylcholine. BALB/c mice were immunized once, i.p. or s.c., with 0.05-2.0 microg HN administered either as free antigen (F-HN), adsorbed to aluminum hydroxide (Al-HN), or encapsulated in liposomes (Lip-HN), separately or together with 1 x 10(2)-4.5 x 10(4) units of free or encapsulated cytokines. Serum antibodies were assayed on days 11-360 by the haemagglutination-inhibition (HI) test and ELISA. Protective immunity against intranasal virus challenge was determined at 9-14 months post-vaccination. The following results were obtained: (1) The efficiency of encapsulation in liposomes was 95, 90 and 38% for HN, IL-2 and GM-CSF, respectively, and the liposomal preparations were highly stable as an aqueous dispersion for > 2 months at 4 degrees C. (2) Following immunization with 0.5 microg Lip-HN, there was an earlier, up to 50-fold stronger, and 3-5 times longer response than that obtained with nonliposomal HN. (3) Coimmunization with free cytokines further increased the response 2-20 times and the two cytokines had an additive effect. (4) Liposomal cytokines were 2-20 times more effective than the free cytokines and their stimulatory effect was more durable. (5) A 100% seroconversion (HI titer > or = 40) was achieved with only 10-25% of the routinely used antigen dose, by encapsulating either antigen or cytokine. (6) The level of protection following vaccination with the combined liposomal vaccines was 70-100% versus 0-25% in mice immunized with Al-HN alone, and no toxicity was observed. In conclusion, our animal experiments show that the liposomal vaccines are superior to the currently used influenza vaccines, increasing the response by 2-3 orders of magnitude in mice. This approach may also prove valuable for subunit vaccines against other microorganisms.

Induction of a protective immunity against Schistosoma mansoni with ovalbumin-coupled Sm37-5 coadsorbed with granulocyte-macrophage colony stimulating factor (GM-CSF) or IL-12 on alum

A previous study has shown that Sm37-5 is a major B cell epitope of Sm37-GAPDH. This epitope is highly antigenic in human infections and IgG antibody reactivity toward this determinant is associated with adolescent resistance to reinfection. This led us to test a synthetic peptide corresponding to Sm37-5, coupled to ovalbumin, as an anti-schistosome vaccine. Although mice injected with Sm37-5-OVA in Freund's adjuvant showed significant protection, immunization in aluminium hydroxide failed to induce protection. The adjuvant effect of cytokines (GM-CSF or IL-12) associated with the antigen on alum was investigated. With each of these two cytokines, significant reductions in the worm burden were obtained (32-38% with GM-CSF and 27% with IL-12, respectively). In addition, a reduction of the egg number trapped in the liver of immunized mice was also observed. Thus, protections were obtained with formulations that could potentially be used in humans.

A Plasmid Encoding Murine Granulocyte-Macrophage Colony-Stimulating Factor Increases Protection Conferred by a Malaria DNA Vaccine

Using the murine parasite Plasmodium yoelii (Py) as a model for malaria vaccine development, we have previously shown that a DNA plasmid encoding the Py circumsporozoite protein (PyCSP) can protect mice against sporozoite infection. We now report that mixing a new plasmid PyCSP1012 with a plasmid encoding murine granulocyte-macrophage colony-stimulating factor (GM-CSF) increases protection against malaria, and we have characterized in detail the increased immune responses due to GM-CSF. PyCSP1012 plasmid alone protected 28% of mice, and protection increased to 58% when GM-CSF was added (p &lt; 0.0001). GM-CSF plasmid alone did not protect, and control plasmid expressing inactive GM-CSF did not enhance protection. GM-CSF plasmid increased Abs to PyCSP of IgG1, IgG2a, and IgG2b isotypes, but not IgG3 or IgM. IFN-γ responses of CD8+ T cells to the PyCSP 280–288 amino acid epitope increased but CTL activity did not change. The most dramatic changes after adding GM-CSF plasmid were increases in Ag-specific IL-2 production and CD4+ T cell proliferation. We hypothesize that GM-CSF may act on dendritic cells to enhance presentation of the PyCSP Ag, with enhanced IL-2 production and CD4+ T cell activation driving the increases in Abs and CD8+ T cell function. Recombinant GM-CSF is already used in humans for medical purposes, and GM-CSF protein or plasmids may be useful as enhancers of DNA vaccines.

Optimization of vaccine responses in early life: the role of delivery systems and immunomodulators

Infant immunization is a particularly important field with multiple challenges for vaccine research and development. There is, together with a high susceptibility to infections, a lower efficacy of most vaccinations in newborns and young infants, compared to those performed later in life. In the present review, the authors focus on problems arising from the attempt to vaccinate against pathogens very early in life, and on the role of selective adjuvants (i.e. antigen delivery systems or immunomodulators) that could be used to: (i) rapidly induce strong antibody responses of the appropriate isotypes; (ii) elicit sustained antibody responses extending beyond infancy; (iii) induce efficient Th1 and CTL responses in spite of the preferential Th2 polarization of early life responses; (iv) escape from maternal antibody mediated inhibition of vaccine responses; (v) show acceptable reactogenicity in early life; and (vi) allow incorporation of several vaccine antigens into a single formulation so as to reduce the number of required injections. How such objectives might be achieved by several of the vaccine formulations currently in development is illustrated by reviewing data from experimental models and clinical studies, when available.

Idiotype Immunization Combined With Granulocyte-Macrophage Colony-Stimulating Factor in Myeloma Patients Induced Type I, Major Histocompatibility Complex–Restricted, CD8- and CD4-Specific T-Cell Responses

Idiotypic structures expressed on the myeloma Ig protein might be regarded as a tumor-specific antigen. Five patients with IgG myeloma were immunized with the purified serum M-component by repeated intradermal injections together with soluble granulocyte-macrophage colony-stimulating factor (GM-CSF). All patients developed an idiotype (Id)-specific T-cell immunity, defined as blood T cells predominantly secreting interferon-γ (IFN-γ) and interleukin-2 (IL-2) (type I cells). Id-specific DNA synthesis was induced in one patient. Delayed-type hypersensitivity against the Id was not evoked. The specific IFN-γ/IL-2 T-cell response was inhibited (46% to 100%) by a major histocompatibility complex (MHC) class I monoclonal antibody (MoAb) in all five patients. A 5% to 37% inhibition by an MHC class II MoAb was seen in four patients. CD4+ as well as CD8+ T cells enriched by magnetic microbeads contained Id-specific cells. The T cells recognized peptides corresponding to the complementarity-determining regions 1, 2, and 3 of the heavy chain of the Id. There was a transient rise of B cells producing IgM anti-idiotypic antibodies in all patients. The results indicate that immunization of myeloma patients using the autologous M-component and soluble GM-CSF may evoke an Id-specific predominantly MHC class I–restricted type I T-cell response.

Idiotype Immunization Combined With Granulocyte-Macrophage Colony-Stimulating Factor in Myeloma Patients Induced Type I, Major Histocompatibility Complex–Restricted, CD8- and CD4-Specific T-Cell Responses

Idiotypic structures expressed on the myeloma Ig protein might be regarded as a tumor-specific antigen. Five patients with IgG myeloma were immunized with the purified serum M-component by repeated intradermal injections together with soluble granulocyte-macrophage colony-stimulating factor (GM-CSF). All patients developed an idiotype (Id)-specific T-cell immunity, defined as blood T cells predominantly secreting interferon-γ (IFN-γ) and interleukin-2 (IL-2) (type I cells). Id-specific DNA synthesis was induced in one patient. Delayed-type hypersensitivity against the Id was not evoked. The specific IFN-γ/IL-2 T-cell response was inhibited (46% to 100%) by a major histocompatibility complex (MHC) class I monoclonal antibody (MoAb) in all five patients. A 5% to 37% inhibition by an MHC class II MoAb was seen in four patients. CD4+ as well as CD8+ T cells enriched by magnetic microbeads contained Id-specific cells. The T cells recognized peptides corresponding to the complementarity-determining regions 1, 2, and 3 of the heavy chain of the Id. There was a transient rise of B cells producing IgM anti-idiotypic antibodies in all patients. The results indicate that immunization of myeloma patients using the autologous M-component and soluble GM-CSF may evoke an Id-specific predominantly MHC class I–restricted type I T-cell response.

Granulocyte-macrophage colony-stimulating factor and the immune system

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional cytokine currently used for the reversal of neutropenia associated with cytotoxic chemotherapy, bone marrow and haemopoietic stem cell transplantation. GM-CSF also modulates the function of differentiated white blood cells. In the context of local inflammatory responses, GM-CSF stimulates macrophages for antimicrobial and antitumor effects. GM-CSF further enhances healing and repair by its actions on fibroblasts and epidermal cells. GM-CSF is the pivotal mediator of the maturation and function of dendritic cells, the most important cell type for the induction of primary T cell immune responses. GM-CSF may enhance antibody dependent cellular cytotoxicity (ADCC) in several cell types, and the generation and cytotoxicity of natural killer (NK) cells. On this basis, GM-CSF may be useful for inducing or augmenting antibody responses to antimicrobial vaccines, to enhance killing of intracellular microorganisms, to accelerate epidermal and mucosal wound healing, and to stimulate protective immunity against tumors.