A Simple Method of Rh Determination

Abstract

IT has been shown that about 0.5 per cent of human sera possess a thermostable factor agglutinating O Rh + red cells sensitized with anti-D antibodies. Only those sera were taken into account which agglutinated sensitized red cells at least in 1 in 8 dilution in saline. Weaker sera gave unreproducible reactions. The strongest serum observed had a titre of 128. According to our experiments¹, the agglutinating factor in the sera observed is an anti-globulin antibody. It may be absorbed from the sera by sensitized red cells and it may be neutralized in the sera by incomplete antibodies regained at 56° C. from cells. This antiglobulin antibody reacts only with immune antibodies after their denaturation in serological reaction, and therefore it is not neutralized by normal serum or by immune serum containing unchanged antibodies (Fig. 1). The discussion on the nature of this antibody and on its eventual role in pathology will be given elsewhere. Here we wish to stress the practical application of our findings.