An anti‐Rh gamma2‐globulin antibody preparation has been developed which can be administered intramuscularly and appears to be both safe and effective in the prevention of experimental Rh sensitization. Nine unsensitized Rh‐negative male volunteers were challenged once a month for five successive months with intravenous injections of 2 ml. of Rh‐positive blood. Four of these nine volunteers were passively protected each month with intramuscular injections of 5 ml. of this antibody preparation, administered 24 hours prior to the antigenic challenge. Three months after the last injection the passively acquired Rh antibodies were no longer demonstrable (by either the saline or indirect antiglobulin technics) in any of the four protected subjects and there was no sign of active antibody production six months after the last injection, whereas four of the five controls were all strongly sensitized.

The results on the use of gammaG-immunoglobulin to Rh factor for the prevention of active immunization of Rh-negative mothers at risk appear most promising. One hundred and seven mothers in the clinical trial have been followed for periods of about 6 months to 1(1/2)12 years after delivery. Of these, 48 were treated mothers who received 5 ml gammaG-immunoglobulin to Rh, and 59 were untreated mothers. Of the 48 treated mothers none are actively immunized; seven of the 59 control mothers have become actively immunized to Rh.

No abstract