الفهرس 
The complement systemOnly 14 pages are availabe for public view
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Abstract
Renal disease is one of the most serious manifestations and a
major cause of death SLE patients especially in the pediatric age
group. Treatment is therefore mandatory and should be started as
early as possible and should be aggressive enough to obtain a
complete remission of renal activity and prevent renal flares.
Although biomarkers have high utility for the diagnosis of
SLE, current serologic and urinary markers do not correlate well with
nephritic activity. We sought to study in pediatric lupus patients one
of the novel biomarkers, anti-C1q autoantibody, that is thought to be
promising in detecting and predicting renal flare in patients with
SLE.
The study was a longitudinal one that extended for one and
half a year from February, 2009 to October, 2010. It included 40
Egyptian pediatric SLE patients with age ranging 5-17 years after
exclusion of the exclusion criteria. Each patient was followed up
clinically and laboratorial every 3 months for a period of one year,
with serial measurement of renal functions and serological markers
(serum levels of C3, anti-dsDNA and anti-C1q).
from the results of our study, it was observed serum anti-C1q
antibodies were positive in 79% of patients with LN while 8 patients
were negative for anti-C1q despite of having active LN in 6 of them.
Anti-C1q was comparable in prevalence and in titre among classes II,
III and IV with comparable results as well among histological indices
of activity and chronicity. Serum anti-C1q correlated well with renal
lupus activity in the form of BILAG index, and could differentiate
patients with active nephritis from non active nephritis at a level of
9.5 U/ml with sensitivity and specificity 48.5% and 79% respectively
with positive predictive value 72%. It also could diagnose patients
with moderate to severe nephritis at the aforementioned level with
sensitivity and specificity 75% and 64% respectively and positive
predictive value 47%.
In the studied sample, serum anti-C1q level was not affected
by patients’ age, duration of LN disease or cumulative doses of
Summary
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immunosuppressive treatment. Also, it didn’t correlate with C3 or
anti-dsDNA levels. However, anti-C1q correlated positively with
ESR, SLEDAI score, 24 hour urinary protein but not creatinine
clearance.
Serum complement C3 level was also comparable with
different classes of LN and although it didn’t show any significant
correlation with any of BILAG index, creatinine clearance or 24 hour
urinary protein. Also, it could not differentiate active from non active
LN and could not differentiate as well moderate to severe LN from
mild or no nephritis.
Similarly, anti-dsDNA was comparable among the included
classes of LN and its titre was comparable among different BILAG
scores. Anti-dsDNA didn’t show any diagnostic efficiency for active
LN and couldn’t differentiate patients with mild or no nephritis from
those with severe or moderate nephritis.
In patients who developed renal activity during the study,
anti-C1q was elevated 3-9 months before clinically &/or laboratory
evident renal flare with average 6.5 months. Also a decline in the
anti-C1q level was noticed after the initial rise suggesting immune
complex deposition, but due to small number of patients, the
predictive value of anti-C1q for subsequent renal flares still needs
further exploration by further studies on larger number of patients for
longer duration of follow-up.
Negative predictive value of anti-C1q for LN couldn’t be
concluded from the studies, because 38 out of the enrolled 40 patients
proved to have biopsy proven LN, while the 2 remaining patients
without evident nephritis didn’t do renal biopsy to know their renal
status.
In conclusion, anti-C1q might be better than anti-dsDNA and
C3 in diagnosing active LN and determining its severity, together
with better efficiency in follow-up response to treatment, while the
ability to predict subsequent renal flare still needs further elucidation.
SummaryIn our opinion, it is recommended to use anti-C1q antibody titre as an
additional tool in the follow-up of patients with LN