Cd3

[Johnsmom]

Can someone explain what this is?

Thanks.

[sf_mom]

Did you happen to mean C3d? Taken from one of LLM post from the Lyme Forum

 

Here's the only explanation of immune complexes that I can understand (this is not specific to C3d - it applies to immune complexes in general):

"An immune complex is formed by the combination of antigens and antibodies. Tests have been designed to measure specific immune complexes. In the case of the Candida-specific immune complex, the test establishes the presence of an abnormally increased Candida load. Immune complex levels also drop quickly when the load is decreased, and this adds to the value of the test. The immune complex test measures how the patient's body is clearing out the invading substance"

-from Candida Related Complex

 

So elevated C3d levels tell you there's a binding of antigen and antibody (I believe C3d suggests an auto-immune response but I'm not positive). I often see rheumatoid arthritis mentioned whenever I google C3d and have felt it is in some way related to my son's complaints of muscle pain. But I don't believe it's specific enough to be used as a diagnostic tool for any particular disease. Only that it's measuring an immune response.

[kimballot]

Can someone explain what this is?

Thanks.

 

Hi - I posted this immune system information a few days ago. I think it is comprehensive and fairly understandable. You can read the whole thing or just use the "find" button to find the information on immune complex.

 

I have been struggling with understanding the immune system and C3D too.

 

My understanding (I am not an immunologist or a scientist by any means) is that when antibodies attack an antigen (like bacteria), they lock into the antigen, making an immune complex of antibody and antigen- and disarm the antigen....then other parts of the immune system break the complex down and remove it from the bloodstream.

 

If there is too much immune complex, then the complex cannot be removed by the blood. When that happens, the complex deposits in tissues like the joints and the kidneys. Lots of kids with PANDAS get painful joints and the thinking is that this is due to this immune complex deposits.

 

C3D is one measure of general immune complex. It is high in autoimmune diseases because there are lots of antibodies attacking antigens (in this case, the body's own tissue). So, C3D is high in lupus, rheumatoid arthritis, and other autoimmune disorders. I don't think anyone has studied it in kids with PANDAS, but I know Dr. B and some other doctors measure it to help see if there is an autoimmune response. My son's was 55 (normal range 0-8), and it really helped me understand his joint pain.

 

Here is the link for the immune system information. I hope that makes sense!

 

http://www.niaid.nih.gov/topics/immuneSystem/Documents/theimmunesystem.pdf