aHUS patients are well aware of Anti-Complement Factor H Auto Antibodies can cause aHUS.
I have heard them called Anti factor H antibodies but you get used to same things being called differently when aHUS is concerned. Let’s go with FHAA and drop the anti-complement.
OK and patients know that FHAA is an auto immune version of aHUS.
Maybe what is the difference?
Its is just that patients with FHAA have a complement system which works.
But they don’t or they would not have aHUS.
Ah but it could work if these FHAAs had not attacked themselves to an important part of complement factor H (CFH).
Important part?
Yes the part which needs to work properly to control complement activation. Its called the ” C-Terminal Region” and specifically the last two bits (19-20) of the 20 bits that make up CFH . With the FHAA attached CFH cannot do that. So aHUS can be the result.
OK bit technical but you say “can be the result”.
Yes FHAA can also cause other conditions like C3 , Lupus, Antiphospholipid Syndrome, some infections and cancers. They get around.
OK back to aHUS, it happens when FHAA sticks to perfectly good CFH?
Yes.
Is that it, CFH will no longer work properly?
Well for as long as there are FHAA to attach to CFH. When new CFH is made and there still enough antibodies they will attach to them in time but if those antibodies reduce in number new CFH will be free of them and can work.
So it is possible that FHAA can be reduced?
Yes but there will always be auto antibodies, another parts of the immune system will continue to create them but they can be destroyed so that only a few exist at any time. Too few to affect CFH working properly.
Can be destroyed?
Yes by plasma exchange and be kept depleted by occasional immunosuppressant therapy.
Wait a minute would that mean that any complement inhibitor treatment could stop.
Yes the aHUS patient’s own complement FH can take over.
Hold on what if the FHAA rise to dangerous levels again?
They take time to build up and if levels are monitored short term immunosuppressant therapy can prevent further build up and auto antibodies only have a limited life so levels fall.
Monitored?
Yes there are relatively inexpensive testing kits available to measure and track antibody levels.
How often should they be tracked to be safe?
There is no specific protocol to follow it depends on how long it is after the original aHUS onset and any treatment starting. It has been suggested monthly at first then four times or even twice a year as time passes.
Does not seem that burdensome and there is other monitoring going on which it could fit alongside. Why does the body create these useless and unhelpful auto antibodies in the first place?
It is a natural part of the adaptive immune system which creates antibodies for anything which it sees as a threat. Why CFH is seen as a threat is anyone’s guess. Such is the fate of all autoimmune diseases which include this version of aHUS among them.
Article No: 790
aHUS is an autoimmune disease?
So aHUS is an autoimmune disease? Well actually not but depending on the definition of aHUS there can be an autoimmune like element. Why so equivocal? Because autoimmunity needs to…
