Coombs' Activity

In Rh testing, the following elements are utilized:

Red blood cells from infant sera
Rh (D) antigen (yellow)

IgG from mother's sera (anti-Rh)
Anti-human IgG (Coomb's reagent)

The following animations demonstrate the differences in method and results of Direct and Indirect Coombs' Tests. Click on the pictures below to begin.

DIRECT

Positive

Animation
(1.1 M)
Netscape 3.03 or older users
Click Here

Negative

Animation
(452 K)
Netscape 3.03 or older users
Click Here

INDIRECT

Positive

Animation
(1.6 M)
Netscape 3.03 or older users
Click Here

Negative

Animation
(516 K)
Netscape 3.03 or older users
Click Here

It is important to remember that the Direct test involves red blood cells with pre-bound anti-Rh antibodies.

Immunological Techniques
University of Arizona
douglas.lake@asu.edu