STEP 5. Optional. Centrifuge; observe for presence of hemolysis
STEP 6. Record results.
(2) Cold incubation should be carried out by using a wet ice bath rather than
putting a rack of tubes in the refrigerator. If the refrigerator is used, the rack should be
placed in a pan of water. There is consistently better heat transfer in a wet bath (either
hot or cold). Some technologists prefer to incubate at room temperature (RT), then
15C to 18C, and then to 4C. There are fewer "nonspecific" results at 18C. Water
baths can be filled with ice and water for temperature adjustment.
(3) Incubation of a separate tube at 37C, rather than using the one
Incubated at RT, will reduce the chances of cold agglutinins binding complement during
RT incubation, and then reacting with the anticomplement components of the
multispecific antiglobulin serum.
b. High Protein.
(a) STEP 1. Add 22 to 30 percent bovine albumin, according to the
manufacturer's directions, to saline tubes (if tubes were not used for 4C incubation).
(b) STEP 2. Centrifuge; observe for presence of agglutination or
STEP 3. Incubate at 37C for 15 to 60 minutes.
(d) STEP 4. Centrifuge; observe for presence of agglutination or
(e) STEP 5. Record the results.
(2) Other potentiating mediums available should be used as directed by the
(3) The addition of albumin is considered to enhance agglutination. It also
enhances the formation of rouleaux, difficult to distinguish from agglutination without
microscopic observation. Cases have been reported of the presence of an antibody
directed against the sodium caprylate used in the manufacture of bovine albumin.
Albumin suppresses hemolysis.