Further experimental studies on the prevention of rh haemolytic disease

Abstract

The results are described of experiments involving the injection of Rh-positive blood into 96 Rh-negative men and designed to find out whether or not the production of immune anti-D can be prevented. Giving 10–20 ml. of anti-D sera containing high titres of complete antibody half an hour after the Rh-positive blood, we found that only about 50% of the injected cells had been cleared within 48 hours and immune anti-D production was enhanced as compared with controls, who received only the Rh-positive blood. Using 35–50 ml. of plasma containing predominantly incomplete antibodies, we found that only 3 out of 21 “ treated ” men developed immune antibodies after three or four stimuli as compared with 11 out of 21 control men, the difference being statistically significant (P =0.02). Examination of these results and those of other experiments which are described suggests that about 95% of the injected cells have to be cleared from the circulation within 24 hours if immune antibody production is to be prevented. The anti-D antibody most likely to be effective in this should have no saline activity and as high an incomplete titre as possible. Preliminary work with anti-D gamma-globulin given intramuscularly has shown that in appropriate dosage it is even more effective in rapidly clearing Rh-positive cells than the most powerful plasma we have used. Before the stage is reached at which a clinical application of the technique in recently delivered Rh-negative women is justifiable, additional experiments are indicated and these are outlined. We are hopeful, however, that the technique will prevent most cases of Rh immunization and thus in time help to eliminate Rh haemolytic disease of the newborn. © 1963, British Medical Journal Publishing Group. All rights reserved.