[CIS-PAGID] low ch50 with normal complement levels?

[Anita Gewurz]

Dear Ashish,

Like Drs. Vasconceles and Gonzalez, I suspect the problem is  
homozygous C2 deficiency and would also check the AH50.

Undetectable CH50 levels can certainly result from complement  
activation, as suggested by Dr. Verbsky, but in the situation you  
describe a congenital C defect is most likely.  Homozygous deficiency  
of an early-acting classical or mannose-binding lectin pathway  
component may present in infancy with infection or lupus-like  
disease.  Normal alternative pathway hemolytic activity (AH50)  
excludes deficiency of C3, C5, C6, C7, C8 or C9.

Patricia Giclas PhD, Director of the Complement Laboratory at National  
Jewish can help http://www.nationaljewish.org/research/diagnostics/adx/labs/complement.aspx 
  .

Sincerely,

Anita Gewurz MD
Section of Allergy and Immunology
Department of Immunology/Microbiology
Rush Medical College
Chicago IL 60612


On Nov 15, 2010, at 7:11 PM, <dmvascon at usp.br> wrote:


> Dear Ashish

>

> I would suggest to test for APH50, in order to evaluate alternate  

> pathway function. The combination of both functional screening tests  

> (CH50 and APH50) is very useful to drive the evaluation of  

> complement defects:

>

> CH50 indetectable, APH50 normal: defects of classical pathway  

> activation

> CH50 normal, APH50 indetectable: defects of alternate pathway  

> activation

> CH50 and APH50 indetectable: defects of membrane attack complex.

>

> These functional tests are fundamental, due to the fact that in a  

> qualitative defect of any component of complement (without  

> quantitative defect), there will be a reduction of the value of the  

> screening test, without reduction of the quantitation of any  

> component by any immunochemical method (nephelometry, turbidimetry  

> etc.).

>

> Usually complement deficiencies present clinical manifestations  

> later in life (usually autoimmunity in classical pathway activation  

> components - C1, C4, C2) and infections by encapsulated bacteria -  

> mainly Neisserial infections - with alternate pathway or membrane  

> attack complex component deficiencies.

>

> Therefore it is important to test for other possible complement  

> defects and follow-up these patients closely to detect any possible  

> clinical and immunological manifestation as early as possible.

>

> Best regards,

>

> Dewton

>

>

> Citando Ashish Kumar <Ashish.Kumar at cchmc.org>:

>

>> Dear Friends,

>>

>> I recently saw a set of twin girls who were born at 32 weeks with  

>> twin-twin transfusion syndrome; the smaller of the two has needed a  

>> couple hospitalizations with URIs due to hypoxia. She has chronic  

>> rhinorrhea, a history of wheezing that responds to bronchodilator  

>> therapy. Someone checked her ch50 and it was <10; recheck showed  

>> the same. Her twin was then checked and hers too was <10. Their  

>> complement levels are all normal, except I don't have results on  

>> C2. They are 18 months old, have normal immune globulins,  

>> lymphocyte numbers and no serious infections. The smaller twin  

>> hasn't needed hospitalization since March, even though she has had  

>> a couple URIs since then - probably because of the season, growth  

>> and better asthma control. So, they were sent to me for consult  

>> because of the low ch50. Since the testing is sensitive to sample  

>> handling, I thought to repeat it and it is still low. I cannot  

>> reconcile the history of no serious infections with low ch50 but  

>> normal complement levels. Is this just a testing aberration? Any  

>> suggestions/ideas?

>>

>> Thanks!

>> Ashish Kumar

>>

>> Ashish Kumar, MD, PhD

>> Assistant Professor

>> Cincinnati Children's Hospital Medical Center

>> Cincinnati, OH

>>

>>

>

>

> <dmvascon.vcf>