d. Autocontrol Positive.
(1) A cold antibody is suggested if reactions detected at room temperature
are weak, or negative at 37C, and/or by antiglobulin technique, or if reactions are
enhanced at 18C to 15C or lower. Reactions at 37C and by antiglobulin test may be
a result of cold agglutinin if cells and serum were mixed at room temperature before
incubating at 37C. The following procedure is suggested:
(a) If the patient has not been recently transfused, absorb cold
autoagglutinins with patient's cells in an ice-slush bath.
(b) Autoabsorption should not be done if the patient has been recently
transfused, because the transfused donor celIs may absorb out a specific alloantibody;
therefore, a prewarmed antiglobulin crossmatch should be done.
(c) Use absorbed serum for reverse grouping, crossmatching, and
identification of alloantibodies that may have been masked by the cold antibody.
Wash patient's cells with warm (37C) saline before grouping and
(2) A serum protein abnormality in the patient may cause reactions that are
detected at room temperature, enhanced at 37C, and negative by antiglobulin test.
This pattern suggests a protein abnormality causing rouleaux formation, particularly
when enhanced in albumin. The patient's diagnosis and results of protein tests can be
informative here. More rarely, with a high-protein method, the albumin-agglutinating
phenomenon may be present. The direct antiglobulin test is usually negative in this
situation. If a protein abnormality is being considered, the following procedure is
Use saline-reactive antiserum to Rh-type patient.
(b) Do a saline-antiglobulin test as the main index of compatibility,
between donor and patient. See the appendix for compatibility testing in presence of
strong rouleaux formation.
(c) Repeat albumin phase, using albumin without the capryilate
stabilizer, when albumin-agglutinating phenomenon is suspected.
(d) Check donor's cells for polyagglutinability.
(3) A warm antibody is indicated if the reactions are detected at 37C, by
antiglobulin technique, or by antiglobulin technique only. The direct antiglabulin test is
usually positive with a warm autoantibody. Consider the following: