Unexpected suppression of anti-Fya and prevention of hemolytic disease of the fetus and newborn after administration of Rh immune globulin.

BACKGROUND

Rh immune globulin (RhIG) has been used successfully for many years for the antenatal suppression of anti-D in D- mothers carrying D+ babies to prevent hemolytic disease of the fetus and newborn. Although the mechanism of RhIG-induced immunosuppression remains unknown, a recent report (TRANSFUSION 2006;46:1316-22) has shown that women receiving RhIG produce elevated levels of transforming growth factor (TGF)β-1, a powerful immunosuppressant cytokine. It was suggested that induction of TGFβ-1 and immunosuppression may be independent of cognate antigen recognition by RhIG. Herein, we present a description of a mother and baby that supports this hypothesis.

STUDY DESIGN AND METHODS

Red blood cells and serum were analyzed using saline-tube indirect antiglobulin test methods. RhIG (RhoGAM) was administered after each amniocentesis performed at 28, 31, and 36 weeks' gestation.

RESULTS

A group A, D-(cde), K+, Fy(a-b+), MNs, Jk(a+b+) mother with no detectable anti-D had an anti-Fy(a) titer of 4096 before RhIG but only 256 after RhIG. Mother gave birth to a group O, D-(cde), Fy(a+b+) healthy baby boy having a weak-positive direct antiglobulin test with anti-Fy(a) eluted from his cells and the titer in the cord serum was 4.

CONCLUSION

This case demonstrates the potential immunosuppressive properties of RhIG for down regulation of a possible clinically significant alloantibody, not anti-D, where no D+ antigen is in the circulation of the mother. The case illustrates the potential utility for using RhIG to modulate antibody levels in situations other than for classical suppression of anti-D production. Although the mechanism in this case is unknown, TGFβ-1-mediated or antibody-mediated immunosuppression to soluble nonparticulate antigens are possible mechanisms.