Information is sparse on C4a, but I’ve tried to gather what there is. C4a is often elevated in chronic inflammation.
Intro to C4a
C4A is part of a “complement” group. The term complement means it is able to kill bacteria and contributes to immune defenses. However, if there are too many compliments, it can cause tissue damage and trigger an allergic reaction.
C4A is an activation protein, which means it also activates the other complement proteins to increase in level (R).
C4a activates Neutrophils, which increases inflammation and free radicals (R).
What Increases C4a?
There are three general pathways by which the body increases C4a: The Alternative Pathway, The Lectin Pathway, and The Classical Pathway.
These pathways are activated by infections, which include bacteria, fungi, viruses, and parasites. Immunoglobulins (IgG, IgM) and CRP can also increase C4a (they can be high in infections). The body often detects infections by the toxins that they give off, so toxins may also increase C4a.
Conditions With Elevated C4a
C4A appears to be an immune marker (has increased levels) in the following disorders:
- Lyme Disease (R, R2)
- CFS (R)
- Psoriasis (R)
- Eczema (R)
- Antiphospholipid syndrome (R)
- Lupus (R) and higher C3a (R)….According to one study, lower C4a contributes to lupus (R).
- AIDS (R)
- Schizophrenia (R)
- Acute pancreatitis (R)
C4A and Mold Illness
C4A levels may be decreased with mold avoidance (anecdotal) and antibiotic treatments (R).
C4A and Lyme Disease
One must realize, however, that C3A and C4A and general markers, and will never be able to diagnose lyme disease specifically (see images above).
C4A and CFS (Chronic Fatigue Syndrome)
One study found that C4a goes up after exercise in people with CFS (R).
A case study found that a CFS patient felt better after their C4a normalized (R).
C4A and Histamine Intolerance
Many people who believe they have histamine intolerance have high C4a because this activates mast cells.
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