The immunologic specificity of antiserum for trypsin-treated red blood cells and its reactions with normal and hemolytic anemia cells.

E RYTHROCYTES modified by sensitization wit-h antil)odies, by treatment with enzymes or viruses, or by storage have showis properties in common with the abnormal, short-lived erythrocytes from patients with certain hemolyt-ic anemias. These are increased fragility, increased susceptil)ility to phagocytosis,’ and agglutination in normal serum. The characteristic agglutination of suital)ly trypsinized red cells by the incomplete antibody found in the sera of hemolytic anemias has proved of definite clinical value.2 ‘ ‘ This investigation was mitiated w’ith the hope that a study of the nature of the changes involved in trypsillizat-ioll might assistin clearing the mire of abnormal hemolyt-ic processes. Wheeler’ suggested that the effect of trypsin and other enzymes on erythrocytes, which permits their agglutination in saline by incomplete antibody, may be due to nonspecific physical or chemical changes of the cell surface which modify their suspension stability when sensitized. Ponder4 has postulated a “loosening” process involving the breaking of bonds and the appearance of less acidic ionized groups, and possibly the incorporation of trypsin into small parts of the protein-containing ultrastructure. We have considered the possibility that the enzyme action may alter the cell surface so that subsurface antigen sites are available, producing, in effect, a new specificity. It was further postulated that this specificity might he detectable in the red cells of certain hemolytic anemias. This could accountfor the presence of antibody in these clinical states. For these reasons, antisera to normal and trypsinized human red blood cells w-ere prepared by immunization of rabbits. The antibody specific for the trypsin cell component w-as separated by proper absorption procedures. The specificity of this antibody w’as also studied with periodate-treat-ed cells and with cells from patients w’ith various types of hemolyt-ic aiiemia.