John G. Gorman

Successful Prevention of Experimental Rh Sensitization in Man with an Anti-Rh Gamma2-Globulin Antibody Preparation: A Preliminary Report

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.

Rh Factor: Prevention of Isoimmunization and Clinical Trial on Mothers

The results on the use of γG-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�12 years after delivery. Of these, 48 were treated mothers who received 5 ml γG-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.

Results of Clinical Trials of RhoGAM in Women

Intramuscularly administered RhoGAM, Rh0 (D) Immune Globulin (Human) has been evaluated for its capacity to prevent the primary Rh immunization of Rh negative women giving birth to ABO compatible Rh positive infants. Since March 1964, over 3,000 women have been admitted to clinical studies in 43 centers ranging geographically from Argentina to Ganada and from Australia to Scotland. RhoGAM prepared at the Ortho Research Foundation used throughout these studies is derived from plasma of persons previously immunized to the Rh0 (D) antigen, and the antibody content of the final preparation is determined by a modification of the radioimmune assay of Hughes-Jones.8

Suppression of the primary Rh immune response with passive Rh IgG immunoglobulin.

THAT passive immunity can block active immunity is an established concept dating from as early as 1909.1 The precise mechanism of the immunosuppressive action, however, is still not clearly underst...