Prospective analysis of the factors influencing the antibody response to hepatitis B vaccine in hemodialysis patients

Erythropoietin enhances immune responses in mice

Erythropoietin (Epo) is the main erythropoietic hormone. Recombinant human Epo (rHuEpo) is thus used in clinical practice for the treatment of anemia. Accumulating data reveals that Epo exerts pleiotropic activities. We have previously shown an anti-neoplastic activity of Epo in murine multiple myeloma (MM) models, and in MM patients. Our findings that this anti-neoplastic effect operates via CD8+ T lymphocytes led us to hypothesize that Epo possesses a wider range of immunomodulatory functions. Here we demonstrate the effect of Epo on B lymphocyte responses, focusing on three experimental models: (i) tumor-bearing mice, (5T2 MM mouse); (ii) antigen-injected healthy mice; and (iii) antigen-injected transgenic mice (tg6), overexpressing human Epo. In the MM model, despite bone marrow dysfunction, Epo-treated mice retained higher levels of endogenous polyclonal immunoglobulins, compared to their untreated controls. In both Epo-treated wild type and tg6 mice, Epo effect was manifested in the higher levels of splenocyte proliferative response induced in vitro by lipopolysaccharide. Furthermore, these mice had increased in vivo production of anti-dinitrophenyl (DNP) antibodies following immunization with DNP-keyhole limpet hemocyanin. Epo-treated mice showed an enhanced immune response also to the clinically relevant hepatitis B surface antigen. These findings suggest a potential novel use of rHuEpo as an immunomodulator.

Intradermal hepatitis B vaccination in patients with advanced chronic renal failure: immunogenicity and follow-up

BACKGROUND

Patients undergoing dialysis usually have a poor response to conventional hepatitis B vaccination.

AIM

To observe the effects of intradermal hepatitis B (HB) vaccination in a 13-month prospective study of adult patients with end-stage renal failure. The patients were with or without previous hepatitis B vaccination, but all had antibody titres <10 mUI/mL.

METHODS

Patients were allotted to two groups: previous hepatitis B virus vaccination and no previous hepatitis B virus vaccination or anti-HBs titres <10 mUI/mL. Patients in both groups received 16 i.d. injections of 0.1 mL of hepatitis B virus vaccine over an eight-week period. Patients had antibody titres assessed before vaccination, 1 month after and every 3 months for a year. Antibody titres >/=10 mUI/mL were considered protective.

RESULTS

Seventy patients completed the protocol. Protective titres were elicited in 82% of each group. Age, time under dialysis, diabetes, smoking and body-mass index were not associated with seroconversion. Persistent protective titres >12 months occurred in 27 (58.7%). Adverse events were trivial.

CONCLUSION

Intradermal hepatitis B virus vaccination is an alternative in end-stage renal failure.

A comparative review of HLA associations with hepatitis B and C viral infections across global populations

Hepatitis B (HBV) and hepatitis C (HCV) viral infection or co-infection leads to risk of development of chronic infection, cirrhosis and hepatocellular carcinoma (HCC). Immigration and globalization have added to the challenges of public health concerns regarding chronic HBV and HCV infections worldwide. The aim of this study is to review existing global literature across ethnic populations on HBV and HCV related human leukocyte antigen (HLA) associations in relation to susceptibility, viral persistence and treatment. Extensive literature search was conducted to explore the HLA associations in HBV and HCV infections reported across global populations over the past decade to understand the knowledge status, weaknesses and strengths of this information in different ethnic populations. HLA DR13 is consistently associated with HBV clearance globally. HLADRB1*11/*12 alleles and DQB1*0301 are associated with HBV persistence but with HCV clearance worldwide. Consistent association of DRB1*03 and *07 is observed with HCV susceptibility and non-responsiveness to HBV vaccination across the population. HLA DR13 is protective for vertical HBV and HCV transmission in Chinese and Italian neonates, but different alleles are associated with their susceptibility in these populations. HLA class I molecule interactions with Killer cell immunoglobulin like receptors (KIR) of natural killer (NK) cells modulate HCV infection outcome via regulating immune regulatory cells and molecules. HLA associations with HBV vaccination, interferon therapy in HBV and HCV, and with extra hepatic manifestations of viral hepatitis are also discussed. Systematic studies in compliance with global regulatory standards are required to identify the HLA specific viral epitope, stage specific T cell populations interacting with different HLA alleles during disease progression and viral clearance of chronic HBV or HCV infections among different ethnic populations. These studies would facilitate stage specific therapeutic strategies for clearance of HBV and HCV infections or co-infections across global populations and aid in identification of HBV-HCV combined vaccine. HLA associations of chronic HBV or HCV development with confounding host factors including alcohol, drug abuse, insulin resistance, age and gender are lacking and warrant detailed investigation across global populations.

Overview of vaccination in chronic kidney disease

Infections are a major cause of death in end-stage renal disease (ESRD) patients, second only to cardiovascular disease, and also contribute to significant morbidity in patients with earlier stages of chronic kidney disease (CKD). Vaccines are a strategy to attempt to reduce morbidity related to infections. Patients with CKD and ESRD may not respond as well to vaccines as patients without kidney failure, but adequate seroresponse with standard or augmented regimens for vaccinations against influenza, hepatitis B, pneumococcus, and varicella have been documented. Influenza, in particular, seems to provide adequate protection with standard dosing regimens. Despite somewhat reduced effectiveness of certain vaccines in patients with CKD, there is emerging evidence of benefit to vaccination in these populations. However, vaccination rates are relatively low. Given the accumulating evidence of benefit, continuing quality improvement programs focused on increasing vaccination rates in patients with all levels of CKD are needed.

Hepatitis B vaccination in human immunodeficiency virus-infected adults receiving hemodialysis

BACKGROUND

The Centers for Disease Control and Prevention (CDC) recommends hepatitis B virus (HBV) immunization for all hemodialysis (HD) patients because they are at high risk of infection. Several studies have shown that the development of protective antibody titers after HBV vaccination is much lower in HD patients. We hypothesized that human immunodeficiency virus (HIV) infection in patients with end-stage renal disease (ESRD) would further impair the immune response to hepatitis B vaccination.

METHODS

We performed a retrospective cohort study of patients undergoing long-term hemodialysis from 1990 to 2002 at the United States-based dialysis facilities of Gambro Corporation, North America. The response rate defined as an increase in anti-HBs levels >/=10 mIU/L after a month of the third dose of HBV vaccination was determined in HIV-infected and a randomly selected group of ESRD patients. The demographic information, laboratory data, and hepatitis B surface antibody (anti-HBs) titers were recorded from the Gambro Corporation database on these patients.

RESULTS

Of the 347 adult HIV ESRD patients, 116 received three doses of recombinant hepatitis B vaccination. Seventy percent were male, and the majority (86%) were black. Of the 116 patients who received three doses of HBV vaccination, 62 (53.4%) developed protective antibody titers. This was comparable to the response rate of 50.4% in the randomly selected 220 non-HIV hemodialysis patients. Among HIV ESRD patients, the mean hemoglobin (Hgb) was higher in patients who developed protective antibody titers (Hgb 11.61 +/- 2 vs. 10.55 +/- 1.86, P value <0.01). On multivariate logistic regression analysis, higher Hgb was associated with protective antibody titers (odds ratio: 1.34, 95% CI 0.99-1.72). Seventy percent of the HIV-infected responders maintained protective antibody titers 6 months after vaccination.

CONCLUSION

Hepatitis B vaccination should be offered to all HIV-infected ESRD patients because over half of the patients with HIV and ESRD can develop protective antibodies.

A comparison of responsiveness to hepatitis B vaccination in patients on hemodialysis and peritoneal dialysis

The doses of hepatitis B vaccine given to peritoneal dialysis (PD) patients are currently based on responsiveness data from hemodialysis (HD) patients. To determine whether the doses are also appropriate from PD patients, we did a head-to-head comparison of short-term and 2-year responses to hepatitis B vaccination of HD patients and PD patients. We evaluated serum titers of the antibody to hepatitis B surface antigen (anti-HBs) after the patients had completed a course of four consecutive intramuscular vaccinations (40 microg of Engerix-B administered into the deltoid muscle at 0, 1, 2, and 6 months) in 69 dialysis patients (47 HD and 22 PD patients) who were both hepatitis B surface antigen (HBsAg) and anti-HBs negative. No patients had received a hepatitis B vaccination prior to the study. There was no significant difference in response to hepatitis B vaccination between the HD and PD groups (78.7% versus 77.3%, p=0.33). The seroconversion rate defined as anti-HBs > or = 10IU/L was influenced only by age (p=0.011). There was also no significant difference in responsiveness between the HD and PD groups (60% versus 50%, p=0.41) at a 2-year follow-up. We conclude that doses of HBV vaccine being used for HD patients are also appropriate for PD patients and a booster dose of vaccine is required to maintain seroprotection for those who lost protecting anti-HBs.

Meta-analysis: the effect of age on immunological response to hepatitis B vaccine in end-stage renal disease

BACKGROUND

Patients on maintenance dialysis typically show a suboptimal immune response to hepatitis B virus vaccine compared with the non-uraemic population. A variety of inherited or acquired factors have been implicated in this diminished response. Age-associated changes in immune status may contribute to decreased vaccine efficacy in older individuals although contradictory results have been reported in individuals with normal kidney function.

AIMS

To evaluate the relationship between age and immune response to hepatitis B vaccine in patients with end-stage renal disease by performing a systematic review of the literature with a meta-analysis of clinical trials.

METHOD

We used the random effects model of DerSimonian and Laird; sources of heterogeneity in effect estimates were explored by performing sensitivity analyses.

RESULTS

We identified 17 clinical trials (1800 unique patients); six (35%) were controlled studies. Pooling of study results demonstrated a significantly decreased risk of response to hepatitis B vaccine among older dialysis patients (overall risk ratio: 0.74; 95% confidence intervals: 0.70-0.79). The P-value was 0.0139 for our test of study heterogeneity. A lowered risk of response to hepatitis B vaccine persisted after exclusion of trials based on plasma-derived vaccines; it was present even when 'older' individuals were defined as being as 50 years (RR: 0.85, 95% CI: 0.75-0.96) or more (cut-off 60 years RR: 0.75; 95% CI: 0.66-0.85). An effect of age on seroprotection rate was present in all clinical reports, irrespective of the geographic origin of the study group: Europe (RR: 0.76; 95% CI: 0.70-0.83) North America (RR: 0.67; 95% CI: 0.60-0.74) or other countries (RR: 0.83; 95% CI: 0.71-0.97). Additional doses of vaccine did not appear to have an impact on RR of response by age.

CONCLUSIONS

Our meta-analysis showed a clear association between older age and impaired response to hepatitis B virus vaccine in end-stage renal disease patients. Such a relationship is biologically plausible. Vaccination schedules with adapted vaccine doses and frequent serum testing for loss of immunity against hepatitis B virus are recommended in elderly patients on maintenance dialysis.

Vitamin E-coated dialyzer membranes downregulate expression of monocyte adhesion and co-stimulatory molecules

BACKGROUND

In patients on chronic hemodialysis leukocyte activation has been related to the impaired function of the immune system. In this study we investigated if the vitamin E-coated dialyzer membrane could reduce monocyte activation thereby improving cellular immunity.

METHODS

This hypothesis was tested in a prospective crossover trial in which 14 stable hemodialysis patients were switched from the baseline hemophane dialyzer to a vitamin E-coated and thereafter a polysulphone dialyzer membrane or vice versa.

RESULTS

Monocyte MHC class I, CD54 and ICAM-1 expression was significantly downregulated when a vitamin E-coated or polysulphone dialyzer was used. The use of a vitamin E membrane specifically decreased monocyte CD40 and CD86 expression. Lectin induced T cell proliferation increased with the use of the vitamin E-coated membrane as compared to polysulphone and hemophane dialyzers.

CONCLUSION

Vitamin E-coated dialyzers induced a less-activated phenotype of monocytes and may improve cellular immunity.

The importance of A3 allele in response to hepatitis B vaccine in end-stage renal disease patients

BACKGROUND

Hemodialysis (HD) patients are at high risk for hepatitis B virus (HBV) infection due to intravenous interventions and therapies: Our aim was to examine how genetic factors affect the response to HBV vaccination in HD patients.

METHODS

The frequencies of HLA class I and II alleles were investigated in responders and nonresponders. Response to vaccination was defined as anti-HBsAg > 10 SI U/L (group I). Nonresponders (anti-HBsAg < 10 SI U/L) were defined as group II. The study included HD patients who were negative for antibodies to hepatitis B surface antigen during pretransplantation evaluation.

RESULTS

Group I consisting of 166 patients and group II, of 90 patients showed a significantly higher frequency of the HLA A3 allele in group I (n = 20) than group II (n = 3) (P = .02). There were no statistical differences between the two groups regarding age and gender distribution (P > .05). Graft outcome was not different between responders and nonresponders (P > .05).

CONCLUSIONS

This preliminary study shows that HLA alleles may have immunomodulatory effects in end-stage renal failure patients. The response to hepatitis B vaccination is affected in multifactorially fashion; HLA A3 may be a genetic predictor for responders, but further studies in larger series are required.

Stage of chronic kidney disease predicts seroconversion after hepatitis B immunization: earlier is better

BACKGROUND

Hepatitis B virus (HBV) infection remains a concern in dialysis populations, and vaccination programs have been less successful than those in the general population. Reasons for poor response include malnutrition, uremia, and the generalized immunosuppressive state of patients with chronic kidney disease (CKD). This prospective cohort study evaluated factors impacting on the effectiveness of a vaccination program before dialysis therapy initiation, including level of kidney function.

METHODS

All patients receiving care in the Kidney Function Clinic (St Paul's Hospital, Vancouver, Canada) were screened for previous HBV infection or vaccination. Those who were marker negative were administered a standardized hepatitis B vaccination schedule recommended for patients with CKD. The primary outcome measure, seroconversion, is defined as hepatitis B surface antibody titer greater than 10 IU 3 months after completion of the vaccination schedule.

RESULTS

The study population of 165 patients included 64% men with a mean age of 60 years, mean serum creatinine level of 3.4 +/- 1.5 mg/dL (300 +/- 133 micromol/L), and median estimated glomerular filtration rate (GFR) of 20 mL/min (interquartile range, 14 to 20). Seroconversion rate was 82%. Multivariate analyses showed the independent predictive value of level of GFR. The model showed that patients with the lowest level of kidney function and who were older and had diabetes were less likely to seroconvert (P < 0.05).

CONCLUSION

This is the largest study to show in a well-characterized cohort that patients with higher GFR levels are more likely to respond to hepatitis B vaccination programs with seroconversion, independent of other factors. Future studies will explore specific mechanisms to explain this phenomenon.

Factors associated with long-term antibody production induced by hepatitis B vaccine in patients undergoing hemodialysis: a retrospective cohort study

STUDY OBJECTIVE

To assess the influence of various clinical factors on antibody production induced by hepatitis B vaccine in patients receiving hemodialysis up to 24 months after vaccination.

DESIGN

Retrospective cohort study.

SETTING

Outpatient dialysis center.

PATIENTS

Adult patients undergoing hemodialysis who received a three-dose series of intramuscular hepatitis B vaccine 40 microg at time 0, 1, and 6 months, according to protocol.

MEASUREMENTS AND MAIN RESULTS

Antibody to hepatitis B surface antigen (anti-HBs) titers were monitored quarterly, and booster doses were given according to protocol. Patients with anti-HBs of at least 10 mIU/ml were considered seropositive. Clinical variables--age, diabetes mellitus status, serum albumin level, and equilibrated Kt/V (eKt/V; Kt/V is a measure of urea clearance during dialysis, used to quantify the delivered dose of hemodialysis)--were compared between seropositive and seronegative patients 12 months (cohort 1) and 24 months (cohort 2) after vaccination. In cohort 1 (66 patients), 24 (36.4%) were seropositive at 12 months. In cohort 2 (40 patients), 15 (37.5%) were seropositive at 24 months. Comparison of seropositive and seronegative patients revealed no statistically significant differences in mean age, sex, serum albumin level, or eKt/V. However, at 24 months, patients with diabetes were 2.5 times more likely to demonstrate seropositivity than those without diabetes (60% vs 24%, respectively, p=0.02).

CONCLUSION

Long-term seroprevalence induced by hepatitis B vaccine was low in our patients 12 and 24 months after vaccination. These results were comparable to previously reported long-term results. Larger, prospective studies would be needed to confirm the finding that patients with diabetes had superior hepatitis B vaccine-induced antibody production at 24 months.

Recombinant hepatitis B vaccine (Engerix-B): a review of its immunogenicity and protective efficacy against hepatitis B

Engerix-B (Hep-B[Eng]) is a noninfectious recombinant DNA vaccine containing hepatitis B surface antigen (HBsAg). It is produced from genetically engineered yeast (Saccharomyces cerevisiae). Intramuscular Hep-B(Eng) [0-, 1-, 6-month schedule] has excellent immunogenicity in healthy neonates and infants, children, adolescents and adults, with seroprotection rates of 85-100% seen approximate, equals 1 month after the final dose of vaccine; seroprotection was defined as an antibody against HBsAg (anti-HBs) titre of > or =10 IU/L. The use of alternative Hep-B(Eng) immunisation schedules (e.g. a 0-, 1-, 2-, 12-month schedule in neonates and infants, 0-, 12-, 24-month or two-dose schedules in children and adolescents, and accelerated schedules in adults) have also been associated with high rates of seroprotection. Seroprotection rates were generally similar with Hep-B(Eng) and the recombinant vaccine Recombivax HB (Hep-B[Rax]) or plasma-derived vaccines (PDVs) approximate, equals 1 month after the final dose (although anti-HBs geometric mean titres were significantly higher with Hep-B[Eng] than with Hep-B[Rax]). One month after the final dose, adults had significantly higher seroprotection rates with the recombinant triple-antigen vaccine Bio-Hep-B (Hep-B[Bio]) than with Hep-B(Eng), although seroprotection rates in healthy infants were similar with Hep-B(Eng) and Hep-B(Bio). Hep-B(Eng) had excellent immunogenicity in several groups considered at high risk of acquiring hepatitis B (e.g. neonates born to hepatitis B carrier mothers and healthcare workers). The immunogenicity of Hep-B(Eng) was reduced in patients with conditions associated with impaired immune function (e.g. patients undergoing haemodialysis or being treated for malignancy), although it had good immunogenicity in patients with diabetes mellitus.Hep-B(Eng) had excellent protective efficacy against HBsAg carriage in healthy infants and children, and in neonates born to hepatitis B carrier mothers (protective efficacy of 95-99%). Hep-B(Eng) also demonstrated good protective efficacy in a number of other high-risk groups. Hep-B(Eng) is generally well tolerated with a tolerability profile similar to that of Hep-B(Rax), Hep-B(Bio) and PDVs. In conclusion, Hep-B(Eng) is a well established, highly immunogenic hepatitis B vaccine with good tolerability and excellent protective efficacy; it offers flexibility through a variety of immunisation schedules. In addition, it appears that Hep-B(Eng) confers immunity for at least 10 years. Hep-B(Eng) has an important role in mass vaccination campaigns against hepatitis B, as well as in groups considered at high risk of acquiring hepatitis B.

Intramuscular versus intradermal administration of anti-hepatitis B vaccine in non-cirrhotic hepatitis C patients

Intradermal vaccination has been proposed as an alternative for the administration of anti-hepatitis B vaccine. Patients (n=66) with chronic viral hepatitis C without cirrhosis were randomised into two groups (intramuscular, n=38; and intradermal, n=28) for prospective immunisation with 20 microg recombinant vaccine, using an ultra-rapid schedule (doses at 0, 15 and 30 days). Sero-conversion (antibody level >/=10 mU/ml) in the intramuscular group was reached by 20, 40 and 72% of patients at days 15, 30 and 60 compared to 4, 8 and 36% for the intradermal group (P=0.010 at day 60). Additionally, levels rose more rapidly in the intramuscular group (P=0.004). Our results do not support the use of intradermal route of immunisation against HBV in HCV patients.

High-dose hepatitis B vaccine in patients waiting for lung transplantation

STUDY OBJECTIVE

To increase the response rate to hepatitis B vaccine in patients awaiting lung transplantation.

DESIGN

Historically controlled, open-label study.

SETTING

Lung transplant clinic at a university hospital.

SUBJECTS

Twenty-seven consecutive individuals with end-stage pulmonary disease who were enrolled to accrue 15 subjects who would complete the vaccine series before transplantation; and 27 lung transplant recipients who were immunized with the conventional dose before the study and served as historical controls.

INTERVENTION

Intramuscular injection of high-dose hepatitis B vaccine 40 microgram at 0, 1, and 6 months.

MEASUREMENTS AND MAIN RESULTS

Hepatitis B surface antibody (anti-HBs) concentrations were measured 1-2 months after completing the high-dose series. Individuals with undetectable anti-HBs received additional vaccine to a maximum of six doses. The response rate to the series was compared with that in the control group. Seventeen individuals in the high-dose group and 14 controls met the study criterion of complete vaccine series before transplantation. The former had a much higher response rate than the latter (9 [53%] vs 1 [7%], p<0.01). Four of six patients who received additional doses of vaccine seroconverted. Two of them underwent transplantation shortly after completing the three-dose series.

CONCLUSION

The high-dose hepatitis B vaccine series produced a protective immune response in lung transplant recipients; however, the response was suboptimal, and alternative immunization strategies should be studied.

The effect of age on immunologic response to recombinant hepatitis B vaccine: a meta-analysis

Hepatitis B vaccine is a key tool for the prevention of hepatitis B infection. Age-associated changes in immune function may contribute to decreased vaccine efficacy in older individuals, although research related to this topic has yielded contradictory findings. We performed a meta-analysis of 24 published trials and studies that evaluated the association of age with response to hepatitis B vaccine, using a random-effects model. Pooling of study results suggested a significantly increased risk of nonresponse to hepatitis B vaccine among older individuals (relative risk [RR], 1.76; 95% confidence interval [CI], 1.48-2.10). An elevated risk of nonresponse persisted even after exclusion of poor-quality studies (RR, 1.63; 95% CI, 1.23-2.15) and adjustment for publication bias (RR, 1.52; 95% CI, 1.26-1.83), and it was present even when "older" individuals were defined as being as young as 30 years. These findings have important implications for individuals at risk for hepatitis B infection, including health care workers and travelers.

Vaccination against hepatitis B infection in patients with end stage renal disease

BACKGROUND

Experience of hepatitis B vaccination in a contemporary renal replacement programme is reported.

METHODS

A total of 406 patients were involved: 214 on haemodialysis, 97 on continuous ambulatory peritoneal dialysis, 67 predialysis (serum creatinine >400 micromol/l), and 28 with a failing transplant. Primary vaccination comprised recombinant hepatitis B vaccine (Engerix B) 40 microg intramuscularly at 0, 1, 2, and 3 months. Booster doses were administered three monthly if anti-HBs titre was <100 IU/l.

RESULTS

Uptake of vaccine was 61% (haemodialysis 70%, continuous ambulatory peritoneal dialysis 62%, predialysis 31%, transplant 61%, p<0.0001). Primary seroconversion occurred in 64% of vaccinated patients (anti-HBs; 10-100 U/l, 33%; >100 U/l, 31%). Booster doses led to further improvement in immunity in 66/115 (57%) patients after a first and 8/20 (40%) patients after a second booster dose, but uptake was again poor (first booster 74%, second 31%). Seroprotection declined unexpectedly rapidly; after a mean of 16 months 71/115 patients (62 %) had a significant fall in their anti-HBs titres; 30/115 (26%) lost detectable antibody.

CONCLUSIONS

Routine hepatitis B vaccination of patients with end stage renal failure is logistically difficult to administer on a large scale; primary seroconversion is relatively poor, but improves after repeated booster doses; protective anti-HBs titres decline rapidly, and yearly antibody checks with selective booster doses will be required to maintain seroprotection. The cost effectiveness of a vaccination programme will vary greatly depending on the prevalence of hepatitis B in the population at risk.

AM3 (Inmunoferón) as an adjuvant to hepatitis B vaccination in hemodialysis patients

BACKGROUND

Patients with end-stage renal disease (ESRD) undergoing hemodialysis have severe alterations in cell-mediated immunity (CMI) that increases their risk of contracting chronic hepatitis B virus (HBV) infection and decreases their protective responses to HBV vaccine. In an effort to improve the humoral response to an accelerated HBV vaccine protocol in these patients, the ability of an immunomodulator, AM3, to improve seroconversion was investigated.

METHODS

A total of 269 patients were enrolled in a multicenter trial. All patients received a DNA recombinant vaccine (40 microg HBsAg/dose/day) on days 0, 10, 21, and 90. AM3 or placebo (3 g/day) was given orally for 30 consecutive days beginning 15 days prior to the first vaccine dose. Anti-HBsAg titers were measured on days 120 and 270 after the beginning of the trial.

RESULTS

After one month, 207 patients could be evaluated and 132 patients after six months. The placebo and AM3-treated groups had comparable seroconversion and protective response rates one month after the final vaccine dose. The AM3 treatment group, but not the placebo group, maintained these protective titers up to six months after the final vaccine dose. At this time, the percentage of high responders (anti-HBsAg>100 IU/L) and mean anti-HBsAg titers in the AM3 group was significantly higher than in the placebo group.

CONCLUSIONS

AM3 is a safe and easily tolerated oral agent that potentiates long-term serological immunity to hepatitis B in hemodialysis patients after vaccination.

Immunogenicity of a recombinant hepatitis B vaccine (Euvax-B) in haemodialysis patients and staff

Hepatitis B vaccine is the most effective strategy for preventing the transmission of hepatitis B virus (HBV) in haemodialysis centers. Nevertheless, lower vaccine responses have been reported in haemodialysis patients as compared with healthy subjects. This study examines the response to Euvax-B in Brazilian haemodialysis patients and staff. A total of 102 eligible patients (n = 42) and staff members (n = 60) consented to be studied. Patients were immunized intramuscularly with four doses of 40 microg of Euvax-B vaccine at 0, 1, 2 and 6 months. In staff members, the vaccine was administered in three doses of 20 microg at 0, 1, and 6 months. Post-vaccine samples were taken from all subjects I month after each dose. The vaccine response was determined by measuring antibody to the hepatitis B surface antigen (anti-HBs) levels using ELISA. Subjects with anti-HBs titres equal to or higher than 10 UI/L were considered immune protected. Of the haemodialysis patients who received four doses of hepatitis B vaccine, 89.5% responded to Euvax-B vaccine. The geometric mean of anti-HBs titres was 322.8 IU/L (95% CI: 317.7-328). Among staff members, 93.3% reached anti-HBs protective titres after the third vaccine dose. The geometric mean of anti-HBs titres was 2,209 IU/L (Cl: 2,198-2,219). Age, male gender and body mass index were not associated with vaccine response in either group. This study showed a good immunogenicity response to Euvax-B in haemodialysis patients and staff.

A 5-year follow-up on antibody response after diphtheria and tetanus vaccination in hemodialysis patients

Chronic renal failure is associated with a T-cell-dependent immune defect. In the past, various studies have focused on the insufficient immune response to vaccination of hemodialysis patients. An impaired vaccination response rate has been reported for vaccines against hepatitis B, influenza, tetanus, diphtheria, and others. However, no data exist on the long-term success of vaccination against tetanus and diphtheria in these patients. The aim of the present study is to investigate seroresponse to tetanus and diphtheria vaccination over a 5-year period. Antibody levels were determined by enzyme immunoassay. Antidiphtheria antibody levels of 31 hemodialysis patients were determined 5 years after vaccination. After 5 years, 10 of 31 patients (32%) had a protective antibody level against diphtheria (>/=0.1 IU/mL), whereas 12 months after vaccination, 26 of 71 patients (37%) were protected. Also, mean antibody levels significantly decreased. Furthermore, antitetanus antibody levels of 21 patients simultaneously vaccinated against tetanus and diphtheria were investigated. After 5 years, 15 of 21 patients (71%) were protected compared with 46 of 71 patients (65%) in the hemodialysis collective studied after 12 months. In the interval between 1 and 5 years after vaccination, significantly more patients in the initial nonresponder group had died than in the responder group; therefore, the overall protection rate observed in vaccinated patients increased. Our results provide evidence that during a 5-year period, antibody persistence against tetanus toxoid is better than that against diphtheria toxoid. Therefore, detection of individual antibody concentrations may be indicated to decide on revaccination.

A placebo-controlled trial to evaluate immunomodulatory effects of paricalcitol

Calcitriol has shown a benefit in various small uncontrolled studies of ex vivo immune function. We hypothesized that paricalcitol, a new vitamin D derivative, will have a positive effect on the immune system with minimal adverse effects on calcium homeostasis. Thirty-one hemodialysis patients not administered vitamin D because of low intact parathyroid hormone (PTH) levels were randomized to placebo or 4 microg of paricalcitol intravenously with the hemodialysis session three times weekly for 12 weeks. Effects on in vivo and ex vivo assessments of immune function were evaluated. All patients achieved the target dose of paricalcitol. Twenty patients were anergic at the start of the study; 4 of 11 patients in the paricalcitol group and 0 of 9 patients in the placebo group converted to reactive (P = 0.09). The in vivo response to standard hepatitis B booster vaccine and in vitro proliferation and release of interleukin-2 (IL-2), IL-6, tumor necrosis factor-alpha, and interferon-gamma from stimulated lymphocytes were not different between the groups. In contrast to clinical immune effects, paricalcitol increased serum calcium levels and decreased PTH and bone alkaline phosphatase levels (all P < 0.05). However, hypercalcemia was infrequent. In vitro experiments showed that paricalcitol led to greater dose-dependent thymidine uptake than calcitriol in lymphocytes isolated from either dialysis patients or control subjects. Paricalcitol has a tendency toward improving delayed hypersensitivity reactions, but did not have other proimmune effects. However, as expected, paricalcitol had significant effects on calcium homeostasis compared with placebo. Thus, patients with low PTH levels are unlikely to experience the proimmune effects of vitamin D therapy without more profound and potentially adverse oversuppression of PTH.

Hepatitis B vaccines: assessment of the seroprotective efficacy of two recombinant DNA vaccines

BACKGROUND

In universal vaccination programs, when there is no postvaccination sero-1 logic assessment of response, there must be confidence that the vaccines used provide a high degree of seroprotection.

OBJECTIVE

This parallel analysis of 2 recombinant hepatitis B vaccines (Engerix B and Recombivax/HB-Vax II) was conducted to review the seroprotective efficacy of each vaccine in defined populations.

METHODS

Clinical studies of the 2 vaccines published as manuscripts or conference abstracts in the public domain between January 1986 and April 1999 were identified retrospectively by unrestricted screening of journals through BIOSIS, MEDLINE, and EMBASE and the Internet. Unpublished or internal company data were excluded to maintain impartiality. The studies were reviewed and analyzed. The studies were not assessed for quality other than a judgment of their eligibility for inclusion in the analysis. The primary outcome measure was the proportion of subjects in defined populations who showed an early seroprotective response to currently licensed vaccination schedules. Summary statistical analyses of seroprotective response rates and 95% CIs were calculated for each vaccine for each population. Seroprotective response was defined by an anti-hepatitis B surface antigen titer > or =10 IU/L measured between 1 and 3 months after the final vaccination. Because the study was designed specifically to review published immunogenicity data, safety data were not assessed. The study was not designed to demonstrate superiority of one vaccine over the other.

RESULTS

A total of 181 clinical studies representing 32,904 vaccinated subjects were reviewed and analyzed, of whom 24,277 had been vaccinated with Engerix B and 8627 vaccinated with Recombivax/ HB-Vax II. Seroprotection was achieved in 20,060 subjects (95.8%) with Engerix B and in 7774 subjects (94.3%) with Recombivax/HB-Vax II in the normal population vaccinated according to currently licensed 3-dose schedules. In a subgroup analysis, response rates in health care workers were 6492 subjects (94.5%) for Engerix B and 3245 subjects (92.2%) for Recombivax/HB-Vax II. Children and adolescents (1-19 years) showed the highest response rates to vaccination (4612 [98.6%], Engerix B; 2292 [98.9%], Recombivax/HB-Vax II). A total of 2875 infants (<1 year) (95.8%) achieved seroprotection with Engerix B; 701 (88.5%) achieved seroprotection with Recombivax/ HB-Vax II.

CONCLUSIONS

Hepatitis B vaccination programs using either Engerix B or Recombivax/HB-Vax II can achieve high seroprotective response rates, particularly in childhood and adolescence. Ideally, younger populations should be a primary target in current universal vaccination programs.

Prevention in liver disease

Prevention has become an important component of medical therapy for a variety of diseases. Preventive strategies in liver disease are relatively underdeveloped and have focused mainly on specific complications of chronic liver disease and vaccination for viral hepatitis. Although public health initiatives designed to prevent certain forms of liver disease are in place, they seem to be underutilized and their utility has not been evaluated. The development of a comprehensive approach using public health initiatives in conjunction with strategies by health care providers is important because of the potential for decreasing the human and health care costs associated with hepatic dysfunction. This article reviews the available literature regarding prevention for health care providers, includes a summary of ongoing public health initiatives, and suggests an approach to prevention in liver disease. It is intended to raise awareness and encourage implementation of preventive strategies in hepatology.

Gastrointestinal and hepatic disorders in end-stage renal disease and renal transplant recipients

Gastrointestinal and hepatic disorders are commonly associated with end-stage renal disease, hemodialysis, and renal transplantation. Recent studies indicate that the prevalence of dyspepsia, ulcer disease, and Helicobacter pylori gastritis is not significantly different from the general population. Bleeding from angiodysplasia, however, is more common in chronic renal failure, as is gastroparesis. The prevalence of chronic hepatitis B has been dramatically reduced among hemodialysis patients since the advent of universal precautions. Response rates to hepatitis B vaccine in noninfected patients, however, are lower in these individuals. Chronic hepatitis C is found in 20% to 25% of HD patients worldwide and accounts for approximately 1% of all infected individuals. Levels of alanine aminotransferase and aspartase aminotransferase are often within normal limits but may be elevated compared with a patient's preinfection levels. Dialysis has been shown to reduce the level of hepatitis C virus viremia. Treatment is similar to non-renal failure patients, although interferon is generally not used in renal transplant recipients owing to concerns of graft failure.

Iron and infection

Intravenous iron therapy maintains iron stores and decreases erythropoietin demand in patients undergoing regular dialysis therapy. Microbiology studies show a close relationship between the availability of iron and bacterial virulence. Iron is also an essential requirement of bacteria for multiplication in the host. Therefore, clinical conditions associated with iron excess in the host may increase the risk for infection. Parenteral iron has already been shown in human and animal studies to be harmful when administered during infection. There is now convincing evidence that hydroxyl radicals, produced either by the Fenton reaction or by the iron-catalyzed Haber-Weiss reaction, are species responsible for the damaging effects of iron. The unavailability of iron limits microbial growth but also impairs host resistance. In end-stage renal disease, patients' overtreatment with iron enhances the pre-existing risk for infectious complications caused by dialysis procedure per se, malnutrition, increased intracellular calcium, as well as low and high molecular weight uremic toxins. Intravenous iron therapy may not only adversely affect phagocytes in end-stage renal disease patients, but also T and B lymphocytes.