Testing for Du.
(a) Cells classified as Du possess the Rho(D) antigen but are not
agglutinated by some or all anti-Rho(D) serums used. The antigen can most
conveniently be demonstrated by showing antibody attachment to the cell surface.
Antiglobulin serum demonstrates whether or not this attachment has occurred after cells
and anti-Rho(D) serum have been incubated together.
(b) Not every anti-Rho(D) serum can be subjected to anti-globulin-
testing, since antiglobulin-reactive antibodies of other specificities may be present.
Check manufacturer's instructions.
1 STEP 1: Place one drop of anti-Rho(D) serum in a labeled test
2 STEP 2: Add one or two drops of 2 to 5 percent cell suspension.
If the initial anti-Rho(D) test was done in a tube, this tube can be used directly
for Du testing.
3 STEP 3: Prepare a control tube. Either of two procedures may be
used. Add one or two drops of the original cell suspension to the labeled control tube OR
use the albumin or reagent control tube from anit-Rho(D) testing.
4 STEP 4: Mix gently and incubate 15 to 30 minutes at 37C
(according to manufacturer's instruction). Following incubation gently re-suspend
cell/serum mixture: centrifuge and examine for agglutination. If strong agglutination of
test RBCs is observed (with no agglutination in the control tube), record the test sample
as Rh positive. If test RBCs are not agglutinated, or show doubtful agglutination,
continue with step 5.
5 STEP 5: Wash cells in both tubes three or four times with large
volumes of saline.
6 STEP 6: Decant thoroughly and blot rim of tubes dry after final
7 STEP 7: Add one or two drops of antiglobulin serum (follow
manufacturer's instruction) to each tube.
9 STEP 9: Re-suspend cell button gently and observe for