Prevention of Rh-haemolytic Disease: a Third Report.

In two papers (Finn et al., 1961 ; Clarke et al., 1963) we described experiments which were successful in preventing Rh immunization in Rh-negative male volunteers. The basis of the procedure was to remove rapidly from the circulation previously injected chromium-tagged Rh-positive red cells by giving hightitre incomplete anti-D either as an infusion of plasma or as gamma2-globulin. In our second paper we stated that the next steps should be to find out whether foetal red cells could be cleared equally well as adult and whether female volunteers could be protected in the same way as men. The results of experiments to test these points form the first part (I) of the present paper. The second part (II) concerns two factors of great importance in the application of the technique to preventing Rh immunization due to pregnancy. These are the frequency with which transplacental haemorrhage from foetus to mother occurs during pregnancy as distinct from at delivery, and the relation of the production of immune antibodies to the size of transplacental haemorrhage assessed after delivery. In the third part of the paper (III) we discuss some of the details of the clinical trial, recently started in Liverpool, of anti-D gamma2-globulin injection given to Rh-negative women after delivery.