Department of Immunology,Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorder (BIRDEM),Shahbag, Dhaka
Background and objectives: It is well known that children with Down syndrome (DS)
suffer from frequent infections. There is an association of certain IgG
subclass abnormalities with the predisposition to recurrent infection of the respiratory
tract. Therefore, the study was conducted to determine the immunoglobulin G1 and
G2 (IgG1, IgG2) profile in children with DS.
Material and methods: Forty children between the ages of 6 months to 12 years
with DS (47 XX/XY, +21) attending the Department of Immunology, BIRDEM were
enrolled in the study. Age and sex matched 30 healthy normal children with 46 XX/XY
were included as control. Enrolled DS and healthy children were divided into
two age groups namely 6 months to 6 years and 7 years to 12 years. Serum IgG1
and IgG2 concentrations were determined by enzyme linked
immunosorbent assay (ELISA) method.
Results: The mean serum IgG1 concentrations of children with DS in
both age groups did not differ significantly from that of normal healthy
children. But the IgG2 level was significantly less (p<0.003 and p<0.004)
in both age groups of children with DS compared to that of control healthy
Conclusion: The study has demonstrated that the serum IgG2 level was
significantly less in children with DS than that of matched normal healthy
control children while there was no deficiency of IgG1.
IMC J Med Sci 2017; 11(1): 1-4
for Correspondence: Dr.
Supti Prava Saha, Lecturer, Department of Pharmacology, Ibrahim Medical
College, 122 Kazi Nazrul Islam Avenue, Shahbag, Dhaka 1000, Bangladesh. Email:
Down syndrome (DS) is one of the most
common autosomal disorders. The prevalence of DS in Europe is reported to be 11.2
per 10,000 live births . In USA the prevalence is 8.27 people per 10,000
population . It is widely accepted that DS children suffer from frequent
infections than normal children. Infections of the respiratory tract,
particularly otitis media, have been identified as one of the most significant
health problems in school age children with DS . In previous study, it has
been found that 54.9% children with DS suffer from ear infection and 11% suffer
from upper respiratory tract infection . The lower respiratory tract
pathology is the most common cause for acute hospital admission among 1 to 5 years
old children with DS . The increased predisposition of infection in
individuals with DS is attributed to underlying defects in the immune system
which include abnormalities of cell mediated and humoral immune response . In
patients with DS, the serum concentration of total IgG may remain within normal range while the IgG2 and IgG4
concentrations are significantly reduced . Also, people with recurrent
sinopulmonary infections were found to have a normal serum immunoglobulin
level, with selective IgG subclass deficiency . Among the four subclasses of IgG, subclass IgG1
and IgG3 are more potent opsonizers than that of IgG2 and igG4 . IgG1and
IgG3 is generally produced in response to protein antigens of bacteria,
viruses, vaccines and foods. IgG2 antibodies predominantly act against
carbohydrate antigens and are important in protection against polysaccharide
encapsulated organisms such as Streptococcus pneumoniae, Haemophilus
influenzae and Neisseria
meningitides . To date there is no study on immunoglobulin subclass
pattern among Bangladeshi children with DS. Therefore, the present study was
conducted to determine the IgG1 and IgG2
profile of Bangladeshi children with DS and whether they are different in
comparison to normal children of the same age group.
The study protocol was approved by the
Ethical Review Committee of the Diabetic Association of Bangladesh. Informed
consent was obtained from parents of each participant prior to enrollment into
population and collection of samples: Children between the ages of 6 months
to 12 years having DS (47 XX/XY,+21) attending the Department of Immunology,
BIRDEM were enrolled in the study. Age and sex matched healthy normal children
with 46 XX/XY were included as control. The children were divided into two age
groups namely, 6 months to 6 years and 7 years to 12 years. About 3 ml of blood
was collected aseptically with venipuncture from all participants for
estimation of IgG subclasses. Serum was immediately separated and stored in -800C
Estimation of IgG subclass: The concentration of IgG1 and IgG2 subclasses
were determined by commercial sandwich enzyme linked immunosorbent assay
(ELISA) kit. The kit was obtained from Elabscience Biotechnology Co, USA. The
detection range of IgG1 and IgG2 was 1.56-100 µg/ml.
A total of 40 children with DS and 30
normal healthy children were included. There were 21 male and 19 female children
with DS. There were 30 and 10 DS children in 6 months to 6 years and 7 years to
12 years age groups respectively. There were 15 normal healthy children in each
age group. The mean concentration of IgG1 antibody of children with DS in 6 months
to 6 years and 7 years to 12 years were 16.4 µg/ml and 9.9 µg/ml respectively
compared to that of 11.5 µg/ml and 6.6 µg/ml. The concentration of IgG1 in DS
and healthy children was not significantly different. The mean concentration of
IgG2 in children with DS was significantly less (p<0.003 and p<0.004) than
that of normal children in both age groups. Among 6 months to 6 years age group
it was 7.4±5.6 µg/ml in DS versus 15±9.4 µg/ml in normal children. In 7 years
to 12 years age group the mean IgG2 levels were 8.6±3.2 µg/ml and 14.9±8.2 µg/ml.
The detail concentration of IgG1 and IgG2 are shown in Table-1.
Table-1: Serum IgG1 and IgG2 levels in children with DS
and in normal children
6 months-6 years
7 years- 12 years
Student’s independent t test was used to
compare between groups.
Mean IgG1 and IgG2 concentrations of DS children was
compared with the levels in normal healthy; DS= Down
syndrome; NH=Normal healthy.
The present study was conducted to assess
IgG1 and IgG2 subclasses patterns in children with DS. Children with DS are
more prone to respiratory tract infection [7,11,12]. We have demonstrated that
in our DS group the serum IgG2 level was significantly less (p <0.05) than
that of matched normal control children. However, the IgG1 levels were not
different from that of control in both age groups. Therefore, along with the
estimation of total IgG, it is important to determine the levels of all IgG
subclasses to ascertain the specific abnormalities. The present study has also
provided the normal range of IgG1 and IgG2 levels of Bangladeshi children
between the ages of 6 months to 12 years. No such values for Bangladeshi
children are so far known or available. Studies in different country have reported
that DS children have reduced or low level of serum IgG2 compared to normal
population [11,12]. Children with DS with this selective IgG2 deficiency are more
susceptible to respiratory tract infection than normal children as because IgG2
is known to act against bacterial polysaccharide antigens of encapsulated
bacteria. In Bangladesh, the prevalence of acute respiratory infection in
children is about 5.5 episodes per child year . It is important to
determine the incidence and prevalence of respiratory tract infections among
IgG2 deficient Bangladeshi DS children as this would help to guide the treatment
and prevention of recurrent infections. Previous study has reported that selenium
supplementation in children with DS has a significant augmentative effect on
the serum concentration of IgG2 and igG4 . Also, intravenous immunoglobulin
replacement therapy has been shown to reduce the rate of respiratory tract
infections significantly in children with recurrent infections and IgG2
findings of IgG2 deficiency would help to guide proper management of infections
of children with DS. The study has further indicated that all IgG subclasses
should be assessed to determine the specific therapeutic intervention.
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