Complement Assays

Complement components are tested to measure the specific components as ___ in serum.

antigens

We measure specific components as antigen in serum to detect:

1. Quantitative ___ caused by deficiencies and chronic inflammation in ___ diseases (which cause increased ___ to infections).

2. Measure ___ of components (can have ___ levels, but decreased functionality causes increased susceptibility to infections).

decreases; autoimmune; susceptibility; functionality; normal

There are ___ and ___ assays used to determine complement abnormalities.

Quantitative; functional

___ (Quantitative or functional) assays commonly measure C1q, C4, C3, C5, factor B, factor H, factor I, and C1 inhibitor.

Through methods of ___ immunodiffusion (RID) and ___.

Quantitative; Radial; Nephelometry

Radial immunodiffusion (RID) is not used as frequently as it is ___ consuming.

Nephelometry is the ___ method and is much faster for Quantitative assays.

time; preferred

The ___ with quantitative assays is that there are only quantitative values – providing no info that the component is actually active/___.

problem; functional

Functional assays are used to measure the ___ of components because the patient could have ___ levels of complement components, but with decreased functionality that leads to increased ___ to infections.

functionality; normal; susceptibility

Functional assays must look at the activity of ___ pathways!

• Pt may have problem w/ one pathway, but no symptoms due to ___ into the other pathways

  • Other pathways can make up for a non-functional one

all; feeding

Functional assays use a test strip w/ 3 different areas to evaluate all pathways:

• Classical - coated w/ ___

• Alternative - coated w/ ___

• Lectin - coated w/ ___

IgM; LPS; Mannose

The functional assay for the classical pathway is the Hemolytic titration (___₅₀) assay.

CH

Hemolytic titration (CH50) assay – measures amount of pt serum needed to ___ 50% of Ab sensitized ___ RBCs.

• Classical is activated by Ab-Ag interaction (how test works)

• Must compare results to healthy patient (normal control)

• Absence of any component (C1-C9) results in abnormal CH₅₀

lyse; sheep

Disadv of Hemolytic titration (CH50) assay:

• difficult to perform

  • no set ___ range

  • labs must get their own standards

• lacks ___

• abnormal results unclear - does not tell which component is the ___ (only indicates ___ testing is required).

reference; sensitivity; problem; further