Influence of Ionic Strength on the Reaction between Anti-D and D Positive Red Cells

Abstract

Summary Both the rate and quantity of iodine labeled anti-D bound to D positive red cells were enhanced significantly when the ionic strength at the time of reaction was reduced by substituting iso-osmotic aqueous solutions of glycine, EACA, sucrose, lactose and glucose for 0.15 M, pH 6.5 phosphate buffer. An almost 4-fold increase in uptake of anti-D to untreated red cells and an approximately 2-fold increase in antibody uptake to papain-modified cells occurred when the ionic strength was reduced from 0.26 to 0.07. The antibody nature of the additional protein bound to the red cell at low ionic strength was supported by the recovery of the additional cell bound radioactivity in the stroma, by quantitative absorption studies, by the reactivity of the additional cell bound radioactivity in the antiglobulin reaction and by the failure to obtain a significant increase in binding of radioactivity to D negative cells under comparable conditions of ionic strength. The enhancement of anti-D uptake to D positive red cells observed following enzyme modification was not additive to that observed when the ionic strength was reduced, indicating that both effects probably act via a common mechanism.