EFFECT OF RENAL HEMODIALYSIS IN END STAGE RENAL DISEASES ON THE LEVEL OF HEPATITIS SURFACE ANTIBODIES AFTER VACCINATION

Document Type : Original Article

Authors

1 Departments of Laboratory, Nephrology National Institute of Urology and Nephrology, Cairo, Egypt

2 Departments of and Urology, National Institute of Urology and Nephrology, Cairo, Egypt

Abstract

Background: The prevalence of viral hepatitis is higher in end stage renal diseases(ESRD) patients with dialysis than in general population, because of the opportunity for exposure during dialysis to blood products, and shared hemodialysis equipments.  The impaired efficacy of HBV vaccine has been attributed to numerous factors such as immune compromised state because of uraemia, age.  Immunization is the most effective way to prevent transmission of HBV.
Objective: To evaluate the effect of chronic renal hemodialysis on the level of hepatitis B surface antibodies after vaccination and to compare between immunogenic seroconversion response to HBV vaccine in hemodialysed patients and healthy individuals.
Patients and Methods: One hundred eighty cases were included in the study (60 controls and 120 hemodialysed patients) at national institute of urology and nephrology (NIUN).  The patients were subdivided into 2 subgroups: 1) Sixty hemodialysed diseased patients due to immunological disease. 2) Sixty hemodialysed diseased patients due to other causes of renal diseases including diabetes mellitus (D.M.) and hypertension (HT).  All subjects received 3 doses of HBV vaccine starting from 11/2013 till 5/2014 (0,1, 6 months). Patients have double the dose (2 ml) of the controls.  After one year of complete vaccination, all subjects were investigated for Hepatitis B surface antibodies titer (HBs Abs titer) in their sera.
RESULTS: There was a statistically significant difference between patient and control groups as regards urea, creatinine, uric acid, sodium, and potassium.  No statistically difference between male and female patients as regards HBs Abtiter, and statistically significant difference of HBs Ab seroconversion when comparing between patients and controls.  There was a statistically significant difference between subgroup 1and subgroup 2. No significant correlation between age, adequacy of dialysis, and HBsAb titer in groups of patients.
Conclusion: The study reported a high response rate to hepatitis-B vaccination among hemodialysed patients. Gender and efficiency of dialysis have no association with response to HBV vaccine. Young age was associated with good response to hepatitis B vaccine, while diabetes mellitus has a poor response to hepatitis B vaccine.

Keywords


EFFECT OF RENAL HEMODIALYSIS IN END STAGE RENAL DISEASES ON THE LEVEL OF HEPATITIS SURFACE ANTIBODIES AFTER VACCINATION

 

By

 

Hala I. Mohamed, Ahmed Hassan* and Shreif Swar**

                                                                                                              

Departments of Laboratory, Nephrology*, and Urology**,

National Institute of Urology and Nephrology, Cairo, Egypt

 

ABSTRACT

Background: The prevalence of viral hepatitis is higher in end stage renal diseases(ESRD) patients with dialysis than in general population, because of the opportunity for exposure during dialysis to blood products, and shared hemodialysis equipments.  The impaired efficacy of HBV vaccine has been attributed to numerous factors such as immune compromised state because of uraemia, age.  Immunization is the most effective way to prevent transmission of HBV.

Objective: To evaluate the effect of chronic renal hemodialysis on the level of hepatitis B surface antibodies after vaccination and to compare between immunogenic seroconversion response to HBV vaccine in hemodialysed patients and healthy individuals.

Patients and Methods: One hundred eighty cases were included in the study (60 controls and 120 hemodialysed patients) at national institute of urology and nephrology (NIUN).  The patients were subdivided into 2 subgroups: 1) Sixty hemodialysed diseased patients due to immunological disease. 2) Sixty hemodialysed diseased patients due to other causes of renal diseases including diabetes mellitus (D.M.) and hypertension (HT).  All subjects received 3 doses of HBV vaccine starting from 11/2013 till 5/2014 (0,1, 6 months). Patients have double the dose (2 ml) of the controls.  After one year of complete vaccination, all subjects were investigated for Hepatitis B surface antibodies titer (HBs Abs titer) in their sera.

RESULTS: There was a statistically significant difference between patient and control groups as regards urea, creatinine, uric acid, sodium, and potassium.  No statistically difference between male and female patients as regards HBs Abtiter, and statistically significant difference of HBs Ab seroconversion when comparing between patients and controls.  There was a statistically significant difference between subgroup 1and subgroup 2. No significant correlation between age, adequacy of dialysis, and HBsAb titer in groups of patients.

Conclusion: The study reported a high response rate to hepatitis-B vaccination among hemodialysed patients. Gender and efficiency of dialysis have no association with response to HBV vaccine. Young age was associated with good response to hepatitis B vaccine, while diabetes mellitus has a poor response to hepatitis B vaccine.

Key Words: ESRD, HBs Ab, immunological causes, diabetes mellitus, hypertension.

 

 

INTRODUCTION

     Viral hepatitis infection is a serious global health problem.  The prevalence of viral hepatitis is higher in dialysed patients than in general population because of the opportunity for exposure during dialysis. Viral infection leads to serious liver diseases including acute and chronic hepatitis, cirrhosis and primary hepatocellular carcinoma.  Liver disease is a significant cause of morbidity and mortality in patients on maintenance dialysis. Hemodialysed (HD) patients are at increased risk of acquiring HBV because of increased exposure to blood products, shared hemodialysis equip-ments, frequent breaking of skin and immune deficiency state (Duranti and Duranti, 2011).

   Immunization is the most effective way to prevent transmission of HBV.  However, it is well established that patients with ESRD including dialysed patients, have an impaired immune response to HB vaccine (Vandepapeliere et al., 2008). So, they have lower seroconversion rates compared to subjects with intact renal function. Moreover, after the completion of vaccination schedule, anti- hepatitis B titer of responder in dialysed patients have low titer that decline logarithmically with time (Ralli Chiara et al., 2016). The impaired efficacy of HBV vaccine has been attributed to numerous factors such as immune compromised state because of uraemia, age, gender and nutritional status.

   Hepatitis B vaccination of hemodialysed patients is performed all over the world. There are also recommendations from world health organizations to vaccinate patients with chronic kidney disease (CKD) prior dialysis, but the implementation of  hepatitis B vaccination program is less common and not well organized (Alicja and Grzegorzewska, 2012).Numerous inherited and/or acquired factors are implicated in diminished immunization following hepatitis B vaccination.

The impaired response to hepatitis B vaccine in dialysed patients has been also attributed to male gender (Yassin and Gupta, 2013). Also, age plays an important role as seroconversion rate to anti-HBs positivity after vaccination was 84% in HD patients below 40 years and only 33% in those ≥ 60 years (Surquin et al., 2010).Moreover, Poor nutritional status, mainly low serum albumin concentration (Brown et al.,2011), serological positivity for hepatitis C virus (HCV) or human immunodeficiency virus (HIV) (AlGhamdiet al., 2013), diabetes mellitus (AlAvian and Tobatabaei, 2010), and vitamin D deficiency were associated with a poor antibody formation upon hepatitis B vaccination(Zitt et al., 2012).

    The present work aimed to compare between immuonogenic seroconversin response to HBV vaccine in hemodialysed patients and healthy individuals.

SUBJECTS AND METHODS

    One hundred and eighty subjects at the NIUN were included in the study starting from 11/2013 till 5/2014. They were divided into 2 groups:

I) Sixty apparently healthy individuals were included as the control group consisting of 26 males & 34 females (age of 47.8  9.7, ranging from 24 to 57 years old).

II) One hundred and twenty ESRD patients were included as the patients group consisted of 63 males and 57 females (age of 48.8 14.3, range from 20 to 55 years old). They were subdivided into 2 equal subgroups according to the underlying cause of dialysis:

1) Hemodialysed diseased patients due to immunological diseases.

2)  Hemodialysed diseased patients due to other causes of renal diseases including D.M. and HT.

All individuals were subjected to:

     Full history taking especially for patients including the underlying diseases, date of starting dialysis, history of vaccination, and infection with HBV.

     Routine kidney function tests (creatinine, uric acid, urea, Na, K.) were measured using fully automated analyzer (DIMENSION, RXL MAX, USA).

     Measurement of HBs Ab titer after complete vaccination by one year using Vidasapparatus (Biomerieux, France) that measures HBsAb by enzyme linked fluorescent assay (ELFA).   Subjects with anti-HBs Ab more than 12 mIU/m L (according to kits) and those having previous history or suffering from HBV were excluded from the study before vaccination. The results were automati-cally calculated using calibration curves stored by the instrument (4-parameter logistics model), and were expressed in mIU/ ml.  The measuring range was 3-500 m IU/ml.

Vaccination program: All subjects received 3 doses of HBV vaccine starting from 11/2013 till 5/2014 (0,1,6 months). Patients have double the dose (2 ml) of the controls.  After one yearof complete vaccination, all subjects were investigated for HBs Abs titer in their sera.

5) According to the kit manufacturer interpretation of results, the seroconversion level of anti-HBs Ab were negative titer < 8, equivocal 8 titer < 12, and positive titer  12 (Huzly et al., 2008).

Statistical analysis: Data were analyzed using statistical program for social science (SPSS) version 20.  Quantitative data were expressed as means standard deviation (SD).  Qualitative data were expressed as frequency and percentage. We used the following tests: t-test Mann Whitney U, Kruskall Wallis, Chi-square (X2), Pearson,s correlation coefficient (r). Probability was considered significant when (p-value < 0.05).

RESULTS

There was no significant difference between patient and control groups as regards age and sex, while a statistically highly significant difference was obvious as regards kidney function tests (Cr, BUN, U.A, Na, K)(Table1).

 

 

 

 

Table (1): Demographic characteristics and laboratory data of groups.

Groups

 

 

Parameters

 Control

Patients

P- value

Age

48.8  14.3

47.7 9.7

>0.05

Sex:  Male

Female

63 (52.5%)

57(47.5%)

26(43.3%)

34(56.7%)

>0.05

Creatinine

10.0 2.9

0.90.3

<0.001

BUN

53.5 16.2

17.4 14.3

<0.001

Uric acid

7.7 2.9

5.2 1.9

<0.001

Na

132.5 5.5

137.2  4.6

<0.001

K

4.8 0.9

4.3  0.5

<0.001

 

      There was no statistically significant difference between males and females as regards HBs Ab titer (Table 2).

 

Table (2): Comparison between males and females patients  according to Hbs Abs titer.

P-value

Median

Means SD

Hbs Ab titer

 

Gender

0.577

 

100(488)

227.322.6

Males

123(491)

251.7 2.5

Females

 

     There was a statistically significant difference of HBS Abs seroconversionon comparing between patient and control groups (Table 3).

 

Table (3): Comparison between patient and control groups according to HBs Ab titer.

Chi- square test

p-value

Patients

Control

Groups    

 

Seroconversion

titer

p<0.01

4 (6.7%)

23 (91.2%)

Negative  [<8]

0 (0%)

7 (5.8%)

Equivocal [≥8- <12]

56 (93.3%)

90 (75%)

Positive [≥12]

60 (100%)

120(100%)

Total

 

     There was a statistically significant difference between subgroup 1, and subgroup 2 (Table 4).

 

Table (4): Comparison between patient subgroups regarding seroconversion of HBs Ab titer.

Chi- Square test

P- value

subgroup (2)

subgroup(1)

Subgroups

 

 

HBs Ab titre

<0.05

17 (28.3%)            

6 (10%)               

Negative  [<8]

5 (8.3%)               

2 (3.3%)              

Equivocal [≥8-  <12]

38 (63.3%)          

52 (86 .7 %)        

Positive [≥12]

60 (100%)           

60 (100%)           

Total                

 

      There was no significant correlation between age, adequacy of dialysis and HBs Ab titer (Table 5).

 

Table (5): Correlation between HbsAbtiter, age and adequacy of dialysis.

P-Value

r

HBsAb titer

 

Patients

0.439

0.071

Age (years)

0.434

0.072

Adequacy of dialysis

 


DISCUSSION

     Hemodialysis patients are at high risk of contracting HB infection as well as other types of blood-borne infections due to the fact that they are exposed to blood and blood products more frequently than the general population (Duranti and Duranti, 2011).  Therefore, vaccinating hemodialysed patients against HBV have become the standard of care. However, it is well known that patients on hemo-dialysis are immune compromised,and this state is mainly due to over-production of interleukin 6 and tumor necrosis factor (TNF) alpha and relatively low production of interleukin 10 (Sharif et al., 2015).This immune suppression status is responsible for a poor response of hemodialysed patients to HB vaccine as opposed to the general population. The efficacy of the vaccine is investigated by measuring titer of HBs Abin the serum with minimum titer of 10 mIU/mL considered to be a response (Al Saran et al., 2014).The seroconversion rate in hemodialysed patients ranges from 50% to 80%, as compared to the general population where the seroconversion rate is over 95% (Keyvani et al., 2014).In consistent with the previous studies, our study showed that the response rate to the vaccine was 75% in ESRD patients on hemodialysis as compared to normal individuals 93.3%. Hepatitis B vaccine in HD patients would be useful to define factors that may affect vaccine response in HD patients.  Unresponsiveness to HBV vaccine is multifactorial, and linked to the presence of several interacting factors. Various findings have shown that response rates are greatest among HD patients younger than 40 years.  Younger people on hemodialysis are more likely to be responders to the vaccine and maintain that type of immune response with the highest ratio being for the age group 18 - 55 years old (El-Charabatyetal., 2015).This was in association with our data, as the age of our patients ranged from 20-58 years old.

    On contrast to our study,Al Saran et al. (2014) showed that the urea reduction ratio and other factors indicating the efficacy of hemodialysis particularly kt/V has been associated with a good response to the vaccine. However, Chang and Liaw (2014) showed weaker response to HBV vaccine associated with inadequate HD. Our study revealed that gender did not affect the response to hepatitis B vaccine.  This result was in agreement with that reported by Pin et al. (2009).

    The diagnosis of diabetes mellitus in patients on hemodialysis was an independent risk factor of being non-responder to the vaccine in our study.  This can explain the statistically significant difference of HBs Abs titer as compared between immunological causes of ESRD patients and other causes of ESRD patients as most of them were diabetics .This result is was agreement with that reported byTseng et al.(2008) who stated noany significant differences of antibody production against hepatitis B surface antigen between diabetic and non-diabetics or male and female subjects.

CONCLUSIONS

     Factors associated with serum antibody level against hepatitis B surface antigen were different in our HD patients, and various factors might be responsible for antibody production and more multicenter investigations need to define these related factors. There was  a high response rate to hepatitis-B vaccination among hemo-dialysed patients. Gender and efficiency of dialysis have no association with response to HBV vaccine.  Young age was associated with good response to hepatitis B vaccine, while diabetes mellitus has a poor response to hepatitis B vaccine.

REFERENCES

1. Alavian SM and Tabatabaei SV.  (2010): The effect of diabetes mellitus on immunological response to hepatitis B virus vaccine in individuals with chronic kidney disease: A meta-analysis of current literature. Vaccine., 28(22): 3773–7.

2. Al Ghamdi SS, FallaTah HI, Fetyani DM, AL-Mughales JA and Gelaidan AT.  (2013):Long term efficacy of the hepatitis B vaccine in high- risk group.  J Med Virol., 85(9):1518-22. 

3. Alicja E, and Grzegorzewska  A. (2012): Hepatitis B Vaccination in Chronic Kidney Disease:  Review of Evidence in Non-Dialyzed Patients. Hepat Mon.,12(11): e7359

4. Al Saran K, Sabry A, Al Halawany Z and Ismail M.  (2014): Antibody level after hepatitis-B vaccination in hemodialysis patients: impact of dialysis adequacy, chronic inflammation, local endemicity and nutritional status.  Saudi J kidney Dis Transpl., 25(1): 185 – 191.

5. Brown CM, Donlon S, O'Kelly P, Casey AM, Collier C, Conlon PJ, and Walshe JJ.   (2011):  A prospective study of hepatitis B vaccination - a comparison PJ, of responders versus non-responders. Ren Fail.,33(3):276–9.

6. Chang ML and Liaw YF  (2014): Hepatitis B Flares in chronic hepatitis B: pathogenesis, natural course, and management. J Hepatol., 61(6) 1407-17.

7. Duranti E and Duranti D. (2011): Polymethyl- methocrylate strengthens antibody response in hemodialysis patients not responding to hepatitis B vaccine: Preliminary data. Menervamedica., 102: 469- 474.

8. El-Charabaty E, Saifan C, Samarneh M and El-Sayegh S. (2015): Variability in Response to Hepatitis B Vaccine in Hemodialysis Patients. J Clin Med Res., 7(5): 315–318.

9. Huzly D, Schenk T, Jilg W and Neumann- Haefelin D.  (2008): Comparison of nine commercially available assays for quantification of antibody response to hepatitis B virus surface antigen. Journal of Clinical Microbiology, 46:1298-306.

10. Keyvani H, Sorabi M, Zamani F, Poustchi H, Ashrafi H and Saeedian F.   (2014):  A population based study hepatitis B virus in northeniran, amol.  Hepat Mon.,14(8):e35577.

11. Pin M, Compte MT, Angelet P, Gallego C, Gutierrez C and Martinez Vea A.  (2009):  Long term evaluation of immune response to hepatitis B vaccine in 136 patients undergoing hemodialysis. Nefrologia., 29(5):415-20.

12. Ralli Chiara I, ImperialiPatriziol I, Gabbrilelli C, Conti P, Lombardi M and Sidoti A.   (2016): Hemodialysis with polymethyl-methacrylate restores the response to Hepatitis B vaccination in chronic dialysis patients: Hypothesized Mechanism of Action. Arch Renal Dis Manag., 2:1-4. 

13. Sharif MR, Chitsazian Z, Moosavian M, Raygan F,  Nikoueinejad H, Sharif AR and Einollahi B.  (2015):  Production of interleukin-6, tumor necrosis factor alpha and interleukin-10 in vitro correlates with the clinical immune defect in chronic hemodialysis patients. Iran J Kidne Dis., 9(2): 84-96.

14. Surquin M, Tielmans C.L and Kulcsar I.  (2010): Rapid enhanced and persistant protection of patient with renal insufficiency by ASO2 V- adjuvanted hepatitis B vaccine, Kidney International., 77(3) 247-255.  

15. Tseng GY, Lin HJ, Fang CT, Cheng YT, Huang CH, Tseng GC, Wang PC, Hung TL, Deng YC, Tsai CC and Yang KY (2008): Haemodialysis reduces the viral load in uremic patients with chronic hepatitis Binfection. Ren Fail., 30: 1000-1005.

16. Vandepapeliere P, Horsmans Y and Moris P.  (2008): Vaccine adjuvant systems containing monophosphoryl  lipid A  and QS21 induce strong and persistanthumoral and T cell response  against hepatitis B surface antigen in healthy adult volunteers. Vaccine, 26(10): 1375-1386.

17. Yassin MH and Gupta V.  (2013):  Role of infection control in Prevention of hepatits B virus in hemodialysis patients. Infects. Disord.  Drug Target.,13(3):162-80.  

18. ZittE, Sprenger-Mahr H, Knoll F, Neyer U and Lhotta K.   (2012): Vitamin D deficiency is associated with poor response to active hepatitis B immunization in patients with chronic kidney disease.  Vaccine, 30(5):931–5.

 

 تأثیر غسیل الکلى فى المرحلة الأخیرة من أمراض الکلى على مستوى الأجسام المضادة   بعد التطعیم بمصل الإلتهاب
الکبدى بى

 

هالة إبراهیم محمد , احمد حسن *, شریف صوار*

المعامل الرئیسیة وأمراض الکلى* والمسالک البولیة **

المعهد القومى للکلى والمسالک البولیة-  جمهوریة مصر العربیة

خلفیة البحث: یعتبر إرتفاع معدل إنتشار الإلتهاب الکبدى بى بین مرضی الغسیل الدموی من أهم المشاکل الصحیة التى تواجه العالم.ولذلک فإن التطعیم من أفضل وأهم الوسائل التى تحد أو تمنع إنتشار هذا المرض. وتعود أسباب  فشل الإستجابة  للتطعیم بین هؤلاء المرضى إلى عدم قدرة الجهاز المناعى على التفاعل ضد الفیروس نتیجة  للتأثیر السلبى لإرتفاع نسبة البولینا فی الدم .

الهدف من البحث:  المقارنة  بین مستوى الأجسام المضادة  لفیروس بى  و مدى الإستجابة للتطعیم بین  مرضى الغسیل الکلوى الدموى والأصحاء.

خطة البحث:  تمت متابعة 120 یجرى لهم مریض غسیل کلوى فى المعهد القومى للکلى والمسالک البولیة، وتم قیاس الأجسام المناعیة  ضد فیروس بى  قبل التطعیم  للتأکد من عدم الإصابة السابقة  بالمرض أو التطعیم.  وقد تم تطعیم المرضى والأصحاء (180 حالة ) بثلاث  جرعات من المصل على مدى ستة شهور، مع ملاحظة أن جرعة المریض (2مللى ) ضعف جرعة الأصحاء (1مللى).وتم إعادة  قیاس الأجسام المناعیة  ضد فیروس بى بعد عام من إنتهاء التطعیم. 

النتائج:  وجدت  دلالة إحصائیة عالیة فى مقاییس البولینا والکریاتینین وحامض البولیک ونسبة الصودیوم والبوتاسیوم فى الدم عند مقارنة  مجموعة المرضى بالمجموعة الضابطة.   ولم توجد علاقة واضحة عند مقارنة نسبة الأجسام المضادة بالنسبة  للجنس فی مجموعة المرضى.  وکانت هناک دلالة إحصائیة عند مقارنة نسبة التحول المصلى بین مجموعة المرضى ومجموعة الأصحاء.  وکما وجدت دلالة إحصائیة عند مقارنة نسبة التحول المصلى بین مجموعة المرضى  ذوى الأسباب المناعیة، ومجموعة المرضى لأسباب أخرى مثل مرض السکر وإرتفاع ضغط الدم.  و لم توجد علاقة واضحة عند مقارنة کفاءة الغسیل والسن ونسبة الأجسام المضادة فى الدم فى مجموعة المرضى .

الاستنتاج: إکتسب مرضى الفشل الکلوى مناعة ضد فیروس بىو لم یکن للجنس وکفاءة الغسیل علاقة بمدى الإستجابة للتطعیم،و کلما قل سن المریض کلما زادت الإستجابة للتطعیم‘ وکانت الإستجابة ضعیفة لدى مرضى السکر.   

 

REFERENCES
1. Alavian SM and Tabatabaei SV.  (2010): The effect of diabetes mellitus on immunological response to hepatitis B virus vaccine in individuals with chronic kidney disease: A meta-analysis of current literature. Vaccine., 28(22): 3773–7.
2. Al Ghamdi SS, FallaTah HI, Fetyani DM, AL-Mughales JA and Gelaidan AT.  (2013):Long term efficacy of the hepatitis B vaccine in high- risk group.  J Med Virol., 85(9):1518-22. 
3. Alicja E, and Grzegorzewska  A. (2012): Hepatitis B Vaccination in Chronic Kidney Disease:  Review of Evidence in Non-Dialyzed Patients. Hepat Mon.,12(11): e7359
4. Al Saran K, Sabry A, Al Halawany Z and Ismail M.  (2014): Antibody level after hepatitis-B vaccination in hemodialysis patients: impact of dialysis adequacy, chronic inflammation, local endemicity and nutritional status.  Saudi J kidney Dis Transpl., 25(1): 185 – 191.
5. Brown CM, Donlon S, O'Kelly P, Casey AM, Collier C, Conlon PJ, and Walshe JJ.   (2011):  A prospective study of hepatitis B vaccination - a comparison PJ, of responders versus non-responders. Ren Fail.,33(3):276–9.
6. Chang ML and Liaw YF  (2014): Hepatitis B Flares in chronic hepatitis B: pathogenesis, natural course, and management. J Hepatol., 61(6) 1407-17.
7. Duranti E and Duranti D. (2011): Polymethyl- methocrylate strengthens antibody response in hemodialysis patients not responding to hepatitis B vaccine: Preliminary data. Menervamedica., 102: 469- 474.
8. El-Charabaty E, Saifan C, Samarneh M and El-Sayegh S. (2015): Variability in Response to Hepatitis B Vaccine in Hemodialysis Patients. J Clin Med Res., 7(5): 315–318.
9. Huzly D, Schenk T, Jilg W and Neumann- Haefelin D.  (2008): Comparison of nine commercially available assays for quantification of antibody response to hepatitis B virus surface antigen. Journal of Clinical Microbiology, 46:1298-306.
10. Keyvani H, Sorabi M, Zamani F, Poustchi H, Ashrafi H and Saeedian F.   (2014):  A population based study hepatitis B virus in northeniran, amol.  Hepat Mon.,14(8):e35577.
11. Pin M, Compte MT, Angelet P, Gallego C, Gutierrez C and Martinez Vea A.  (2009):  Long term evaluation of immune response to hepatitis B vaccine in 136 patients undergoing hemodialysis. Nefrologia., 29(5):415-20.
12. Ralli Chiara I, ImperialiPatriziol I, Gabbrilelli C, Conti P, Lombardi M and Sidoti A.   (2016): Hemodialysis with polymethyl-methacrylate restores the response to Hepatitis B vaccination in chronic dialysis patients: Hypothesized Mechanism of Action. Arch Renal Dis Manag., 2:1-4. 
13. Sharif MR, Chitsazian Z, Moosavian M, Raygan F,  Nikoueinejad H, Sharif AR and Einollahi B.  (2015):  Production of interleukin-6, tumor necrosis factor alpha and interleukin-10 in vitro correlates with the clinical immune defect in chronic hemodialysis patients. Iran J Kidne Dis., 9(2): 84-96.
14. Surquin M, Tielmans C.L and Kulcsar I.  (2010): Rapid enhanced and persistant protection of patient with renal insufficiency by ASO2 V- adjuvanted hepatitis B vaccine, Kidney International., 77(3) 247-255.  
15. Tseng GY, Lin HJ, Fang CT, Cheng YT, Huang CH, Tseng GC, Wang PC, Hung TL, Deng YC, Tsai CC and Yang KY (2008): Haemodialysis reduces the viral load in uremic patients with chronic hepatitis Binfection. Ren Fail., 30: 1000-1005.
16. Vandepapeliere P, Horsmans Y and Moris P.  (2008): Vaccine adjuvant systems containing monophosphoryl  lipid A  and QS21 induce strong and persistanthumoral and T cell response  against hepatitis B surface antigen in healthy adult volunteers. Vaccine, 26(10): 1375-1386.
17. Yassin MH and Gupta V.  (2013):  Role of infection control in Prevention of hepatits B virus in hemodialysis patients. Infects. Disord.  Drug Target.,13(3):162-80.  
18. ZittE, Sprenger-Mahr H, Knoll F, Neyer U and Lhotta K.   (2012): Vitamin D deficiency is associated with poor response to active hepatitis B immunization in patients with chronic kidney disease.  Vaccine, 30(5):931–5.