Analysis index

1 ml serum, fresh (no older than a few hours) or frozen (wherever possible)

C3d-test: < 40 µg/ml
C1q-test: < 55 µg/ml

Progress checks of immunological illnesses, differential diagnosis of vasculitis

The various biological characteristics of immune complexes (i.e. intermediate sized immune complexes are more likely to cause vasculitis than very small or very big immune complexes) led to the recommendation of using at least two test systems, based on different test methods for the demonstration of circulating immune complexes. Immune complexes (ZIK) are part of the immune defense and develop through reactions of various antigens with antibodies of classes IgG, IgA, IgM. The binding of complement components leads to a quick ZIK-elimination via cellular elements of the monocyte-macrophage-system. The antigenic stimulus of trivial infections only leads to a moderate increase of ZIK, as these are eliminated quickly. Long-term antigen supply in chronic infections and autoimmune illnesses leads to increased ZIK-values, especially in vasculitis, SLE and other collagenosis, rheumatoid arthritis, glomerulonephritis, autoimmune hepatitides, HIV-infections and syphilis. Increased values are also seen in malignomas.