Anti-D immunoglobulin in Rh(D) negative volunteers: clearance of Rh(D) positive red cells and kinetics of serum anti-D levels.

Properties of a new anti-D immunoglobulin were assessed in Rh(D) negative healthy male adults. Six volunteers received intravenous, and five volunteers intramuscular injections of 200 micrograms anti-D, 48 hours after pre-treatment with 5 mL of Rh(D) positive erythrocytes. Immediately after intravenous administration of anti-D, a rapid decrease of the Rh(D) positive erythroyctes was noted. After intramuscular injection of anti-D, there was a lag phase of 6 hours until the erythrocytes decreased, and the elimination rate was slower. Twenty-four hours after injection of anti-D, the Rh(D) positive erythrocytes were at the detection limit or no longer detectable in all volunteers. After intravenous administration, anti-D serum levels decreased from 45 ng/mL at 2 hours to 29 ng/mL at 24 hours, whereas after intramuscular administration, anti-D became detectable at 4 hours and increased to 11 ng/mL at 24 hours. During subsequent months, anti-D serum levels decreased at similar rates in both groups. After six months, anti-D was not detectable in any of the volunteers. Thus, the new anti-D immunoglobulin induced elimination of the Rh(D) positive erythrocytes and suggested that Rh(D) immunization of the volunteers was prevented.