Artículo Original
The inverse correlation between
serum levels of anti-pneumococcal and ferritin after pneumococcal vaccination
in splenectomised beta thalassemia major
Correlación inversa
entre los niveles séricos de anticuerpos antineumocócicos y ferritina después
de la vacunación antineumocócica de pacientes con beta talasemia mayor
esplenectomizados
Karamatollah Rahmanian1 ORCID: https://orcid.org/0000-0003-3324-7651
Masihollah Shakeri2
ORCID: https://orcid.org/0000-0001-9184-9912
Vahid Rahmanian1
ORCID: https://orcid.org/0000-0003-3460-7495
Shahryiar Najafi-Tireh
Shabankareh2 ORCID:
https://orcid.org/0000/0002/6763/1320
Fatemeh Sotoodeh Jahromi2 ORCID: https://orcid.org/0000-0001-9293-4158
Abdolreza
Sotoodeh Jahromi2* ORCID: https://orcid.org/
0000-0002-2131-2113
1 Research
Center for Social Determinants of Health, Jahrom University of Medical Siences,
Jahrom, Iran.
2 Zoonoses Research Center, Jahrom
University of Medical Sciences, Jahrom, Iran.
Autor
para correspondencia: sotoodehj2002@yahoo.com
ABSTRACT
Splenectomy
is necessary in beta thalassemia major patients when the spleen becomes
hyperactive, leading to extreme destruction of erythrocytes. This study
assessed the ferritin effect on serum pneumococcal antibody response following
pneumococcal vaccination, in patients with beta thalassemia major after
splenectomy. In this case series study, convenience sampling was used to
recruit 347 splenectomised beta thalassemia patients under the auspices of
Jahrom University of Medical Sciences. Demographic data such as age, sex, and
time after splenectomy were recorded by a questionnaire. All participants had been
splenectomised and received a dose of Pneumovax® 23 vaccine 14 days before
surgery. The IgG antibody responses to pneumococcal vaccine and levels of serum
specific ferritin were determine by commercial enzyme immunoassay kits. For the
analysis, SPSS software version 16 was used. A p-value less than 0.05 was
considered statistically significant. Most of the participants (63.4%) were
hypo-responders to pneumococcal vaccine. Also, serum anti-pneumococcal IgG
antibody was related to post splenectomy duration and serum ferritin (p<
0.001), but not to gender (p> 0.05). An important result was a relation of
serum anti-pneumococcal IgG antibody to serum ferritin according to post
splenectomy duration groups. Therefore, in three groups of post splenectomy
duration, the serum ferritin was higher in hypo-responder than in good
responder subjects. Our results indicate that serum anti-pneumococcal IgG
antibody decreased with increment of serum ferritin and post splenectomy
duration. Thus, there is a need to re-address the approach towards
revaccination in this immune-compromised group of patients by administering a
booster pneumococcal vaccination in an attempt to recover immunity and reduce
morbidity.
Keywords: pneumococcal vaccines;
ferritins; splenectomy; beta thalassemia; Iran.
RESUMEN
La esplenectomía es necesaria en pacientes con beta
talasemia mayor cuando el bazo se vuelve hiperactivo, lo que lleva a una destrucción
extrema de los eritrocitos. Este estudio evaluó el efecto de la ferritina sobre
la respuesta de anticuerpos antineumocócicos en suero después de la vacunación
antineumocócica, en pacientes con talasemia beta mayor a los que se les realizó
esplenectomía. En este estudio de serie de
casos, se utilizó un muestreo de conveniencia para reclutar a 347 pacientes con
beta talasemia esplenectomizados bajo los auspicios de la Universidad de
Ciencias Médicas de Jahrom. Los datos demográficos como la edad, el sexo y el
tiempo después de la esplenectomía se registraron mediante un cuestionario. Todos los participantes fueron
esplenectomizados y recibieron una dosis de la vacuna Pneumovax® 23, 14 días
antes de la cirugía. Las respuestas de anticuerpos IgG a la vacuna neumocócica
y los niveles de ferritina sérica específica se determinaron mediante estuches
comerciales de inmunoensayo enzimático. Para el
análisis se utilizó el programa SPSS versión 16. Un valor de p inferior a 0,05
se consideró estadísticamente significativo. La mayoría de los participantes
(63,4%) resultaron hiporrespondedores a la vacuna antineumocócica. Además, el
anticuerpo sérico antineumocócico IgG se relacionó con la duración de la
esplenectomía y la ferritina sérica (p<0,001), pero no con el género
(p>0,05). Un resultado importante fue la relación del anticuerpo sérico IgG
antineumocócico con la ferritina sérica según los grupos de duración
postesplenectomía. Por lo tanto, en tres grupos
de duración posterior a la esplenectomía, la ferritina sérica fue mayor en los
sujetos con hiporrespuesta que en los sujetos con buena respuesta. Nuestros
resultados indican que el anticuerpo sérico IgG antineumocócico disminuyó con
el incremento de la ferritina sérica y la duración posterior a la esplenectomía.
Por lo tanto, existe la necesidad de volver a abordar el enfoque hacia la
revacunación en este grupo de pacientes inmunocomprometidos mediante la
administración de una vacunación antineumocócica de refuerzo en un intento por
recuperar la inmunidad y reducir la morbilidad.
Palabras clave: vacunas neumocócicas; ferritinas; esplenectomía;
talasemia beta; Irán.
Recibido: 14 de enero de 2022
Aceptado: 14 de marzo de 2022
Introduction
Thalassemia
is an inherited condition involving an abnormal form of hemoglobin, which leads
to disturbances in globin chain. Active erythropoiesis and anemia are among the
consequences of this disorder. Although thalassemia occurs across the globe, it
is most prevalent in North Africa, the Mediterranean area and Western Asia.
Newborn babies are affected by the disease by a rate of two in 1,000 across the
globe.(1) In
Iran, however, the rate is twice as high, with the frequency of thalassemia
gene being 4-10%.(2)
Splenectomy
is necessary in beta thalassemia major (BTM) patients when the spleen becomes
hyperactive, leading to extreme destruction of erythrocytes and thus growing
the need for regular blood transfusions, which in turn outcomes more iron
accumulation. Splenectomy, the aim of which is to reduce blood consumption, is
the major therapy for iron overload among transfusion-dependent patients with
thalassemia.(3) Splenectomy
as well as changes in immune system seem to be the major causes of infectious
diseases in these patients. Infections are the second leading cause of
mortality and main cause of morbidity among patients with beta thalassemia
disorder.(4)
Spleen is essential for the elimination of non-opsonized bacteria, which are
highly encapsulated organisms. Thus, the absence of spleen makes the immune
system ineffective in eliminating such bacteria and opens the way to sepsis and
overwhelming post splenectomy infection (OPSI) accounting for over 70% of cases
of OPSI, while under normal conditions only 5% of sepsis are caused by these
bacteria.(5) This
infection was often caused by capsular polysaccharide of Streptococcus pneumoniae and sometimes by Hemophilus influenzae type b (Hib). An increase of immune children
to Hib with advancing age was found, indicating an increase in children´s
contact with this microorganism during childhood.(6) Thus,
it is highly recommended vaccination against such encapsulated bacteria
especially in children with BTM who need to receive vaccination prior to
splenectomy.(7) In
Iran this procedure is carried out 14 days before splenectomy.
In a
previous study we found that immunity level significantly decreased with longer
period after pneumococcal vaccination in splenectomised beta thalassemia (SBT)
patients. Also, 66.2% of patients were non-immune to pneumococci.(8) Hemophilus influenzae type b antibody
level was lower in SBT patients than non splenectomised beta thalassemia.(9)
Iron
is an important material for the growth of all human cells including white
blood cells, but large amounts of iron and iron overload lead to iron toxicity.(10)
In BTM, red blood cell destruction causes iron accumulation in the body,
which is called iron overload. Patients suffering from iron overload, in
addition to cell damage, also increase the risk of infection. Iron overload is
the main cause of immune abnormalities.(11) Aleem
et al., suggested higher counts of circulating B-cells and IgG immunoglobulin
after reduction of iron overload with deferasirox therapy among 17 beta
thalassemia patients.(12) On
the other hand, iron overload creates an antigen exhibition blockage.(13) Nevertheless,
Pardalos et al., reported higher serum ferritin levels among BTM
patients than in control subjects, but no different for serum immunoglobulin
levels between both groups.(14)
Due to
adverse effect of iron overload on immune response, this study assessed the ferritin
effect on antibody response following pneumococcal vaccination in patients with
BTM after splenectomy.
Materials and Methods
Study design
In
this case series study, convenience sampling was used to recruit 347 SBT
patients under the auspices of Jahrom university of Medical Sciences. The
patients who had received immune suppressive therapy prior the research were
excluded from the research. The research project commenced on January 1st,
2016 and terminated on June 3rd, 2016. The study was approved by the
local ethical committee (ethical
code: IR.JUMS.REC.1400.057) and all participants were
asked to complete an informed consent. Demographic data such as age, sex, and
time after splenectomy were recorded by a questionnaire. No participants had
primary immune deficiency or acquired immune deficiency syndrome. All
participants were splenectomised and received a dose of Pneumovax® 23 vaccine,
14 days before surgery. The research instruments included data collection form
aimed at collecting demographic data and medical history of the participants in
the research.
Sampling
The
research process started with the collection of blood samples from the
participants to be assayed for antibody and ferritin measurements. The IgG
antibody responses to pneumococcal vaccine were assayed to measure pneumococcal
capsular polysaccharide (PCP) IgG. To that end, 23 polysaccharides, which
accounted for 80% of the virulent serotypes, were isolated from Streptococcus pneumoniae. Prior to
testing serum samples, anti-PCP IgG antibodies were controlled by pneumococcus
IgG immunopotency level/E-DG-MZ-001/04-04, ZenTech, Belgium, in which PCP
antigen was used to pre-coat. After achieving 1:510 dilutions, a standard curve
was drawn using reference plasmas as calibrators with sensitivity 6.9mU/mL.
Each sample on the curve was interpolated to anti PCP IgG antibodies in mU/mL
as specified by the kit. According to directions on this kit, the result interpretation
was done as follows:(5)
- Lower
than 250 mU/mL: deficient in anti PCP IgG antibodies or hypo-responder.
- Equal
to or more than 250 mU/mL: good responder or immune to pneumococcal infection.
The
levels of serum specific ferritin were determined by an enzyme immunoassay kit
(Human ferritin ELISA, Biovender, Cat. No.: RCD012R).
The
SBT patients were divided into three groups according to duration after
splenectomy: group 1 included post splenectomy duration (PSD) till 36 month
(PSD36), group 2 included PSD 37-120 month (PSD120) and group 3 included PSD
over 120 months (PSD over 120).
Statistical analysis
Continues
variables are presented as mean ± standard deviation and categorical variables
are presented as number and percent. We used the independent t-test and One-way
ANOVA to compare the means and chi square to compare the proportions according
to age, sex and duration after splenectomy. Also, the dependency of antibody
titers to serum ferritin was analyzed by linear regression test. For the
analysis we used SPSS software version 16 (SPSS Inc., Chicago, IL, USA). A
p-value less than 0.05 was considered statistically significant.
Results
Table 1. The
percent or mean of studied variables in all participants and by sex of
patients.
|
Variables |
All |
Female |
Male |
P |
|
Number (%) |
347 (100.0) |
173 (49.9) |
174 (50.1) |
- |
|
Age, year: mean (SD) |
18.8 (5.5) |
18.2 (4.4) |
19.3 (6.4) |
0.065 |
|
Post splenectomy duration, month: mean (SD) |
106.1 (66.6) |
93.4 (58.2) |
118.7 (71.9) |
< 0.001 |
|
Anti-pneumococcal IgG antibody, mU/mL: mean (SD) |
206.7 (70.8) |
213.7 (66.7) |
199.8 (74.3) |
0.069 |
|
Ferritin, ng/mL: mean (SD) |
2134.7 (1614.1) |
1960.6 (1449.3) |
2307.8 (1749.7) |
0.045 |
SD: Standard deviation.
The patients were divided into two groups based on their
serum APA titers (mU/mL):
hypo-responders and good responders. While 220 patients (63.4%) fell
into the first category, the rest, 127 patients (36.6%) fell into the second.
Patients in good responder group were more female (p= 0.009) and younger (p=
0.024), and had lower ferritin level (p<0.001) and a shorter duration after
splenectomy (p< 0.001) than hypo responder group (Table 2).
Table 2.
Comparison of studied variables between hypo-responder and good responder
group.
|
Variables |
Hypo-responder |
Good responder |
P |
|
Number (%) |
220 (63.4) |
127 (36.6) |
- |
|
Sex, male: number (%) |
122 (55.5) |
52 (40.9) |
0.009 |
|
Age, year: mean (SD) |
19.3 (4.9) |
17.9 (6.3) |
0.024 |
|
Post splenectomy duration, month: mean (SD) |
134.2 (60.3) |
57.3 (45.3) |
< 0.001 |
|
Ferritin, ng/mL: mean (SD) |
3025.6 (1362.2) |
591.4 (377.0) |
< 0.001 |
SD: Standard deviation.
As shown in Table 3, the age and serum level of ferritin
increased with PSD increment (p< 0.001). On the contrary, the serum level of
APA declined with PSD increasing (p< 0.001). The immunity to Streptococcus pneumoniae decreased with
advancement of time after splenectomy (p< 0.001).
Table 3. Age
and serum concentration of anti-pneumococcal antibody and ferritin according to
post splenectomy duration.
|
Post splenectomy duration |
1-36 month |
37-120 month |
>120 month |
P |
|
Number (%) |
72 (27.7) |
130 (37.5) |
145 (41.8) |
- |
|
Age, year: mean (SD) |
15.8 (4.5) |
16.7 (2.7) |
22.2 (6.1) |
< 0.001 |
|
Anti- pneumococcal IgG antibody, mU/mL: mean (SD) |
283.3 (47.9) |
208.5 (58.0) |
167.1 (58.3) |
< 0.001 |
|
Hypo-responder, number (%) |
7 (9.7) |
77 (59.2) |
136 (93.8) |
< 0.001 |
|
Ferritin, ng/mL: mean (SD) |
735.4 (840.3) |
1761.6 (1158.9) |
3164.1 (1592.7) |
< 0.001 |
SD: Standard deviation.
Among PSD36 group, the ferritin level was higher in
hypo-responder subjects compare to good responder ones (3251.0 ± 0.0 vs. 464.5
± 128.9, p< 0.001). Also, in PSD120 and PSD over 120 patients, the ferritin
level was higher in hypo-responder subjects compare to good responder
individuals (2467.4 ± 922.5 vs. 736.2 ± 527.8, p< 0.001; 3330.1 ± 1502.4 vs.
655.2 ± 144.0, p< 0.001, respectively).
The serum APA level was
related to PSD (constant: 282.59, B: - 0.715, p< 0.001) and ferritin
(constant: 283.83, B: - 0.036, p< 0.001) inversely when variables entered
separately in linear regression analysis model. When the variables sex, age,
PSD and ferritin level were entered together in linear regression model, APA
was related to both PSD and ferritin level (Table 4).
Table 4.
Relation of anti-pneumococcal IgG antibody with sex, age, duration after
splenectomy and serum ferritin level according to regression analysis.
|
Variables |
Constant |
B unstandardized |
B standardized |
P |
|
Post splenectomy duration, month |
298.93 |
- 0.288 |
- 0.271 |
< 0.001 |
|
Serum ferritin, ng/mL |
|
- 0.029 |
- 0.658 |
< 0.001 |
Discussion
Streptococcus pneumoniae
infections were found to be a high risk factor to SBT patients, which may be as
a result of the reduced antibody response to bacterial polysaccharide antigens attributable
to splenectomy.(15) Meanwhile,
though preventive measures such as pneumococcal vaccination can be adopted,
their efficacy needs to be proved.(16) Nowadays,
pneumococcal vaccination in SBT individuals is mentioned.
The
result of this study demonstrated that 63.4% of SBT patients were
hypo-responders to pneumococcal antigens. Similar results have been reported by
Rao et al, who reported that 42% of the immunized SBT patients were
defensive to Streptococcus pneumoniae.(17) This
indicates that measurement of post-vaccination antibody levels can be used to
identify poor responders who are likely to be at increased risk of pneumococcal
infection. Also, the results of our study showed that 93.8% and 59.2% of SBT
patients who belong to PSD over 120 and PSD 120 were hypo-responders,
respectively, compare to patients among PSD 36 group that 9.7% were hypo-responders.
Higher PSD and ferritin level were found for
hypo-responder SBT patients. Furthermore, patients with
prolong PSD had higher ferritin level and lower immunity to Streptococcus pneumoniae. This indicates
that higher level of ferritin and prolongation of time after splenectomy and
pneumococcal immunization may cause immunity deterioration. This idea was shown
by the linear regression model indicating that the level of PSD and ferritin
has a significant reverse effect on serum APA. Important result of our study
was a higher level of ferritin in the hypo-responders compared to the good
responders in each PSD categories.
A low number of T suppressor cells (CD8)
without change of T helper cells (CD4) was reported in patients with
hereditary hemochromatosis (HH) compare to healthy controls.(13)
Also, a decrease in the CD8 count and an increase in the CD4/CD8
ratios were observed in HH patients; there was a positive correlation between
CD4/CD8 ratios and amount of phlebotomy.(13) This result is in line with
our study where 90.3% of SBT patients were immune against pneumococcal
pneumonia until 36 month after vaccination. In contrast to our study, the
increment of absolute numbers of CD8 cells in HH patients and an
antigen presentation obstacle time and dose dependent in iron overload status
was suggested.(13) The results obtained here
suggest that an immunization policy with pneumococcal polysaccharides might
help to protect the majority of SBT patients against invasive pneumococcal
diseases; therefore, it is suggested that the vaccine be administered. The
significant inverse relation between mean anti-pneumococcal IgG titers and time
post splenectomy that was found in our study indicates a decline of
anti-pneumococcal IgG titer along the time. Thus, with progression of time
after splenectomy, antibodies against polysaccharide antigens will decrease and
patients will remain at significant risk for such infections. Published data
indicate that vaccinated immune compromised patients, who had a nearly normal
antibody response to pneumococcal vaccine and immune patients to Streptococcus pneumoniae, will require
revaccination to maintain their immunity.(15,18)
It is notable that some factors such as chronic kidney
disease and hemodialysis can reduce the immune response to vaccines;(19, 20) renal
function tests and immunity to the pneumococcal vaccine were not investigated
in this research.
The present study indicates a significant reverse
relation between serum APA and serum levels of ferritin. Also in a study,
thalassemia patients who was on the iron chelation therapy showed no
differences in immunoglobulin concentrations compare to healthy subjects.(21) BTM
patients who receive multiple blood transfusions and express a decreased T4+
cell activity should be considered as a high risk population for the
development of clinical infection. The evident association between iron
overload and T cell abnormalities observed in another study suggests that
correct and continuous regulation of annual iron balance in BTM patients is an
important factor in minimizing this immunological disturbance.(14)
Conclusion
Our results indicate that
serum anti-pneumococcal IgG antibody decreased with increment of serum ferritin
and PSD. Thus, there is a need to re-address the approach towards revaccination
in this immune-compromised group of patients by administering a booster
pneumococcal vaccination in an attempt to recover immunity and reduce
morbidity. Further researches with larger samples from other areas of Iran and
analytic studies are recommended for this approach.
Acknowledgment
This research was funded by
the vice-chancellor for research of Jahrom University of Medical Sciences and
Health Services. The authors are appreciative to all the patients and their
families for their kind cooperation in this research.
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Conflict of interest
The authors declare that
there is no conflict of interest.
Author’s
contributions
Karamatollah Rahmanian: conception of the study and
participated in the statistical analysis.
Masihollah Shakeri: contributed to the writing of the
manuscript.
Vahid Rahmanian: design and management of the study,
writing the manuscript and implementing all comments from the reviewers.
Shahriyar Najafi-Tireh Shabankareh: translation of the
manuscript.
Fatemeh Sotoodeh Jahromi: contributed to the writing and
translation of the manuscript.
Abdolreza Sotoodeh Jahromi: conception, design and
management of the study, writing the manuscript and implementing all comments
from the reviewers.
All
authors read and approved the final manuscript.
* Zoonoses Research Center, Jahrom
University of Medical Sciences, Jahrom, Iran.