TESTS FOR COMPLEMENT

Question 1

Methods that are used to screen for individual complement components

Answer 1

• Radial immunodiffusion (RID)
• Nephelometry

Bothe RID and nephelometry give quantitative results but are unable to measure complement activity

Question 2

The most commonly used functional assay; measures the amount of patient serum required to lyse 50% of a standardized concentration of antibody-sensitized sheep erythrocytes; measures call components from C1 to C9; an assay for classical pathway

Answer 2

Hemolytic titration (CH50) pathway

Question 3

An additional CH50 test has also been developed based on the lysis of liposomes that release an enzyme when lysed. It is more accurate than traditional CH50:

Answer 3

Liposome lysis

Question 4

The best screen for complement abnormalities; solid-phase IgM attached to the walls of microtiter plates is used to initiate complement activation; anti-human antibody to C9 conjugated to alkaline phosphatase is the indicator of complement activation. When a substrate is added, if any C9 is present and the antibody conjugate has attached, a color change will be evident

Answer 4

ELISA (Enzyme-Linked Immunosorbent Assay)

Question 5

This assay can be performed in the same manner as the CH50, except a buffer is added to chelate calcium which blocks the classical pathway activation

Answer 5

AH50 assay

Question 6

What animal RBC is used in CH50 assay?

Answer 6

Sheep RBC

Question 7

What animal RBC is used in AH50 assay?

Answer 7

Rabbit RBC

Question 8

In the AH50 assay, what are the components in the buffer that is added to chelate calcium?

Answer 8

• Magnesium chloride
• Ethylene glycol tetraacetic acid