Universality of anti-A and anti-B human isolysins.

Many studies of ABO isolysins have indicated that some A, B, and O sera show no isohemolytic activity. The apparent incidence of ABO isolysins in human sera varies widely, from 0.24 of A sera containing anti-B isolysin [8] to more than 90 "6 of 0 and B sera containing anti-A isolysin [4]. Reports of many other wide-ranging values have led t o the general assumption that isolysins, in contrast to ABO isoagglutinins, do not follow the rule of Landsteiner. It has been suggested that one important reason for such variable values lies in variable levels of sensitivity of the methods used in the several studies; the possibility exists that a sufficiently sensitive test would show isolysins in all the sera in which Landsteiner's rule would predict them. Thus by increasing the amount of serum per cell up to 200: 1, and using 51Cr release from labelled A cells as a measure of hemolysis, POLLEY et al. [h] concluded that all 0 sera lyse A cells. In this study the spectrum of ABO isolytic activity of human sera was determined by a simple direct test which permits the detection and relative quantification of frank hemolysis.