[CIS PIDD] Low CH50

[Patsy Giclas]

Dear Santhosh,

I have been following the train of emails regarding the measurement of CH50
and thought I¹d offer what I can on the subject.

In today¹s lab world, collection of samples for complement analysis has
improved greatly from even 10 to 15 years ago.  The number of times I have
been able to prove that improper sample collection was the cause for a low
CH50 is very small (<1 %) compared to the number of samples my lab has
received over the years for CH50 or other complement functional tests.  It
is true that some of the complement proteins are heat labile, the first to
go being C1q, C2, factor B and C8.  For the most part, samples that have
little or no CH50 activity have either a missing protein (C1 ­ C9) in the
classical pathway (simple complement deficiency), a missing or dysfunctional
control protein (FH or FI, regulatory deficiency that results in secondary
loss of C3, or C1INH that results in decreased C4 and C2), or an activator
of the classical pathway that depletes the proteins before freezing and
during thawing.  The latter could be a cryoglobulin that precipitates when
the specimen is being frozen or thawed, immune complexes in the circulation,
or bacterial or other contamination.  There are also autoantibodies against
C1q, C1INH, C4 and C3bBb that can inactivate the target protein or prolong
the activity of the enzyme (C3bBb).

Thanks for the kind words, Anita
Good luck with your patient, Santhosh

Patsy
---------------------------------------------------------
Patricia C. Giclas. Ph.D.
Director, Complement Laboratory
Advanced Diagnostic Laboratories
Professor, Pediatrics Dept,  Allergy and Immunology Division
National Jewish Health
1400 Jackson St., Denver, CO 80206 U.S.A.

Office: D409, Neustadt Building
Phone: 303-398-1217
Fax: 303-270-2128
Email: giclasp at njhealth.org



From: Santhosh Kumar/FS/VCU <skumar at vcu.edu>
Reply-To: "pagid at list.clinimmsoc.org" <pagid at list.clinimmsoc.org>
Date: Wed, 11 Jul 2012 11:27:41 -0600
To: "pagid at list.clinimmsoc.org" <pagid at list.clinimmsoc.org>
Subject: Re: [CIS PIDD] Low CH50

Thank you all for the information.
 
She has a normal IgD and CRP level so far and she has been afebrile for a
while now. She never had a consistent pattern to her fevers and not all of
her febrile episodes were documented. If the febrile episodes persist, we
will proceed with further workup for periodic fevers.
 
Santhosh Kumar, MD
Assistant Professor,
Allergy & Immunology
Ph-  804-628-1605
Fax-804-828-1751


-----pagid-bounces at list.clinimmsoc.org wrote: -----

> To: "pagid at list.clinimmsoc.org" <pagid at list.clinimmsoc.org>

> From: Anita Gewurz

> Sent by: pagid-bounces at list.clinimmsoc.org

> Date: 07/11/2012 10:31AM

> Subject: Re: [CIS PIDD] Low CH50

> 

> Dear Santhosh, 

> 

> Regarding complement testing for in vitro consumption and other assays,

> contact:

> 

> Patricia Giclas PhD, GiclasP at NJHealth.org

> Director, Complement Laboratory

> Professor, Pediatrics Dept,  Allergy and Immunology Division

> National Jewish Medical and Research Center

> 1400 Jackson St., Denver, CO 80206  Office: M013f, BB Building

> TEL 303-398-1217

> FAX 303-270-2128

> www.njc.org/research/clinical-labs/about/learn/diaglab/complement.aspx

> <http://www.njc.org/research/clinical-labs/about/learn/diaglab/complement.aspx

> > 

> 

> Your DDx should include periodic fever syndromes.

> 

> Anita Gewurz MD

> Department of Immunology/Microbiology

> Rush University Medical Center

> Chicago IL 60612

> Tel (312) 942-6296

> Fax (312) 563-2201

> 

> From: pagid-bounces at list.clinimmsoc.org [pagid-bounces at list.clinimmsoc.org] on

> behalf of Santhosh Kumar/FS/VCU [skumar at vcu.edu]

> Sent: Wednesday, July 11, 2012 8:58 AM

> To: pagid at list.clinimmsoc.org

> Subject: [CIS PIDD] Low CH50

> 

> Dear All,

>  

> I have 6 y/o F who was referred to me by my ID colleague for recurrent febrile

> episodes since starting school. She has not had any major infections which

> needed hospitalization. Most of her febrile episodes were thought to be

> virally related. Her immune work up is normal except for low CH50 levels

> (repeated x 2- 12 and 15U/ml). His other classic pathway complements are

> normal (c2, c3, c4, c6, c7, c8,c9). AH50 is pending. I had heard of falsely

> low CH50 levels in past depending on the assay used. My question is:

>  

> Is this a false low CH50 level and if so is there a  better assay which can be

> used to confirm

>  

>  

> Thank you,

>  

> Santhosh Kumar, MD

> Assistant Professor,

> Allergy & Immunology

> Medical college of Virginia

> Ph-  804-628-1605

> Fax-804-828-1751




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