QUESTION: Does the serum contain antibodies?
Are they agglutinating or nonagglutinating (incomplete)?
Do they show hemolytic activity?
At what temperature do they react optimally?
What is their thermal range?
What is their specificity?
Are they autoantibodies or alloantibodies?
EXPLANATION: These questions can be answered by the regular
serologic techniques used in the blood bank for detection and
identification of antibodies. A few minor modifications are useful.
As patients with immune hemolytic anemia often have low serum
complement levels, it is advisable to set up a duplicate set of tests,
to which an equal volume of fresh compatible inert serum has been
added, as a source of complement. Some workers prefer the
mixture of patient's serum and complement to be in the pH range of
6.5 to 6.8, which is achieved by adding a one-tenth volume of 0.2 M
HCI to the serum, as this seems to be optimal for the detection of
warm and cold hemolysins.
Both warm and cold reacting autoantibodies give enhanced
reactions with enzyme-treated RBCs; thus, it is useful to
include such cells in the serum-screening procedure. Hemolysis of
enzyme-treated cells is much more commonly observed, than
hemolysis of untreated RBCs.
It is extremely important that tests, set up at 37C, are strictly at
37C. In order to do this, the patient's serum, reagent red blood
celIs, and albumin are warmed to 37C separately before mixing.
The tests are then centrifuged at 37C (see later), and the cells are
washed at 37C with 37C saline for the antigiobulin test. If this is
not done carefully, (with careful control of the temperature at each
stage), positive results may be misinterpreted, leading to possible
confusion in the classification of the immune hemolytic anemia, and
clinical significance of the autoantibody. This is particularly
important when antibodies reactive at room temperature are