Determining the clinical significance of alloantibodies.

The detection and identification of red cell alloantibodies are important processes familiar to all laboratory professionals. A term frequently utilized to describe an alloantibody likely to cause an adverse event is 'clinically significant'. The laboratory usually assesses the clinical significance of alloantibodies based upon specificity, serologic phases of reactivity and cross-match results and make transfusion recommendations accordingly. However, using specificity, reactivity patterns and cross-match results alone cannot always distinguish between clinically significant and nonsignificant alloantibodies. Searches for 'compatible' blood can occur when alloantibodies are identified and 'incompatible' cross-matches occur, leading to inappropriate delays in transfusion and potentially causing patient harm. Cellular assays, such as the monocyte monolayer assay, can be used as an adjunct to predict transfusion outcome. Current routine serology assays will not predict with absolute certainty whether 'incompatible' red cells transfused to a recipient with an alloantibody will be destroyed or whether that recipient will suffer the devastating clinical consequences of a hemolytic transfusion reaction. The monocyte monolayer assay can be of particular assistance when the antibody specificity is of 'variable' clinical significance or the antibody specificity is to a high incidence antigen and rare blood is requested. Finally, it is important to remember that laboratory professionals will be called upon for advice and information by clinicians and patients regarding transfusion recommendations. We are all partners working together to determine the optimal transfusion option. And we must reaffirm to all that transfusion should never be withheld from a patient whose life depends on urgent transfusion. [ABSTRACT FROM AUTHOR]