c. Antibodies, stimulated by RBC antigens, usually react in a predictable
manner, depending on the specificity of the antigen. Some of the antigens stimulate the
production of lgM and others of lgG antibodies. The lgM antibodies react by
agglutinating the RBCs, while the lgG antibodies sensitize (coat) the RBCs that can
then be agglutinated by antiglobulin serum. Some antibodies (both lgM and lgG) are
able to activate complement. If the bound complement proceeds to completion of the
sequence, the RBCs will be lysed. If the sequence is not completed, the cell-bound
components can be detected with cell-bound polyspecific or monospecific (C3 or C4)
antiglobulin serum (see Lesson 3, Section Il).
d. The Standards for Blood Banks and Transfusion Services (SBBT) requires
the serum of all donors and recipients to be tested by methods that will demonstrate
hemolyzing, agglutinating, and coating antibodies.
e. The detection of antibodies in recipients is more important, than detection in
donors. Mollison says, "There does not seem to be a single record in the literature of a
hemolytic reaction due to destruction of the recipient's red cells by an incompatible
antibody other than anti-A and anti-B in the donor's plasma." He also feels that an
antibody in a recipient that does not react above 30C has little clinical importance.
To detect antibodies with varying serologic characteristics, several different
temperatures, and techniques must be used. Records should include the strength of
the positive reactions and the temperature, suspending mediums, and so forth, at which
reactions were observed. This information, gleaned from the antibody-screening test
results or from incompatible cross matches, is useful in planning the best procedures for
definitive identification and may offer some clues as to probable specificity.
a. Saline (May be Used at Several Temperatures.)
(a) STEP 1. Place 2 to 3 drops of serum in carefully labeled tubes.
STEP 2. Add 1 drop of 2 to 5 percent suspension of reagent RBCs
to each tube.
(c) STEP 3. Mix, centrifuge, and observe for hemolysis and
agglutination; record the results.
(d) STEP 4. Optional. Incubate for 15 to 30 minutes at the desired