ABSTRACT
The transfusion m anagem en t o f patients w ith au toan tibodies to red cells o r platelets com plicates n o rm al com patib ility testing for these patients.
RED CELL AUTOANTIBODIES
A classification o f red cell au toan tibodies is show n in Figure 22.1. Red cell au toan tibodies are a rb itra rily divided in to “cold” and “w arm ” antibodies, b u t the d istinction is n o t absolute. C old antibodies are antibodies w hich preferentially agglutinate red cells at low tem peratures. They characteristically agglutinate red cells at 4°C and at ro o m tem pera tu re (22°C), b u t ten d n o t to cause agglutination at 37°C. W arm an tibodies on the o th er han d tend to be inactive at room tem p era tu re b u t do cause agglutination at 37°C. C old antibodies are m ostly IgM an tib o d ies and, therefore, m ay cause in travascular hem olysis due to com plem ent fixation. H em oglobinem ia and hem oglobinuria are com m on. W arm autoan tibodies are alm ost all IgG antibodies. W arm antibodies tend to cause predom inantly extravascular hemolysis. H em oglobinem ia o r hem oglobinuria is rare. Regardless o f the type o f hemolysis, e ither condition m ay result inj severe anem ia and give rise to difficulties w ith com patib ility testing and , hence, delay in the availability o f phenotypically com patib le red b lood cells.
