Problems associated with compatibility testing for patients with autoimmune hemolytic anemia.

Two major areas where problems are encountered when performing compatibility testing for AIHA patients are ABO/Rh typing and crossmatching blood for transfusion. ABO/Rh typing is usually not a problem with warm type AIHA (WAIHA), but sometimes false positive Rh typing results may occur with reagents containing potentiators (eg, albumin). Approaches to overcoming this problem include using reagents not having potentiators, or removing IgG from RBCs (eg, using chloroquine) before typing. Major problems are encountered when typing patients with cold agglutinin syndrome (CAS). These can usually be resolved by using RBCs that have been washed at 37 degrees C, and testing the serum with A, B and O cells at 37 degrees C using the "prewarm" technique. When crossmatching blood for patients with CAS, all tests should be carried out with saline or LISS-suspende RBCs, strictly at 37 degrees C; albumin or enzyme techniques should be avoided. If sera from WAIHA are reacting with all RBCs, the presence of underlying alloantibodies must be excluded by performing absorption studies with with autologous, or homologous RBCs. If alloantibodies are present, they should be identified, and "antigen negative" blood crossmatched. If alloantibodies are not present, and if time allows, the less important autoantibody specificity may be studies. If specificity is shown (eg, auto anti-e) and appropriate donors (eg, e negative) are available, with relative ease, then it is preferable to use this blood. If the appropriate compatible donors are rare [eg, Rhnull, LW-, U-, Kp (b-)], they should not be used for AIHA but should be reserved for patients with alloantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)