c. Antlglobulin Test. See Lesson 1, Section Il for a complete discussion of the
Albumin tests incubated at 37C.
(1) STEP 1. Fill the tube with saline, centrifuge, decant the saline,
resuspend the cells, and repeat 3 or 4 times.
(2) STEP 2. Following the centrifugation for the last wash, decant all the
saline and flick the last drops off the mouth of the tube. Resuspend the cell button.
(3) STEP 3. Add the amount of antiglobulin serum recommended by the
manufacturer, and mix gently.
(4) STEP 4. Centrifuge, gently resuspend cells, and examine for
agglutination or hemolysis.
STEP 5. Record the results.
(6) STEP 6. Add one drop of known lgG-sensitized cells to all negative
tests. Centrifuge; read for agglutination.
If active antiglobulin serum is present, the sensitized cells will be agglutinated.
If known sensitized cells are not agglutinated, the negative antiglobulin test is
not valid and the entire procedure must be repeated.
d. Enzyme Tests.
(1) Enzyme methods are important additions to antibody detection and
identification because they enhance the reactions of some blood-group antibodies that
might otherwise be undetected, notably weak Rh and Kidd anti-bodies. On the other
hand, enzymes may damage the antigenic determinants of some blood-group systems,
for example, M, N Fya, and Fyb; therefore, antibodies directed against these antigens
may not be detected. Enzymes may be employed in a simple one-stage technique,
where the enzyme is mixed directly with the test cells and the serum to be tested, or in a
two-stage technique, where the test cells are pretreated before use. The one-stage
procedures are used for detection, identification, and crossmatching, while the two-
stage is best suited to detection and identification. Enzyme tests can be incubated at
room temperature and/or 37C. After incubation at 37C, with some procedures, the
cells may be washed and antiglobulin serum added. An autocontrol should always be