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Does Rh immune globulin suppress HLA sensitization in pregnancy?

Authors

  • Richard M. Kaufman,

    Corresponding author
    1. Westat, Rockville, Maryland
    2. Institute for Transfusion Medicine, Pittsburgh, Pennsylvania
    • Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
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  • Karen S. Schlumpf,

    1. Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
    2. Westat, Rockville, Maryland
    3. Institute for Transfusion Medicine, Pittsburgh, Pennsylvania
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  • David J. Wright,

    1. Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
    2. Westat, Rockville, Maryland
    3. Institute for Transfusion Medicine, Pittsburgh, Pennsylvania
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  • for the Darrell J. Triulzi,

    1. Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
    2. Westat, Rockville, Maryland
    3. Institute for Transfusion Medicine, Pittsburgh, Pennsylvania
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  • NHLBI Retrovirus Epidemiology Donor Study-II (REDS-II)

    1. Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts
    2. Westat, Rockville, Maryland
    3. Institute for Transfusion Medicine, Pittsburgh, Pennsylvania
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  • This work was supported by NHLBI contracts N01-HB-47168, -47169, -47170, -47171, -47172, -47174, -47175, and -57181.

Address correspondence to: Richard Kaufman, MD, Blood Bank, Amory 260, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115; e-mail: rmkaufman@partners.org.

Abstract

Background

How Rh immune globulin (RhIG) prevents sensitization to D antigen is unclear. If RhIG Fc delivers a nonspecific immunosuppressive signal, then RhIG may inhibit sensitization to antigens other than D. HLA antibody prevalence was compared in previously pregnant D– versus D+ women to investigate whether RhIG suppresses HLA sensitization.

Study Design and Methods

In the Leukocyte Antibody Prevalence Study (LAPS), 7920 volunteer blood donors were screened for anti-HLA and surveyed about prior pregnancies and transfusions. A secondary analysis of the LAPS database was performed.

Results

D– women not more than 40 years old (presumed to have received antenatal with or without postpartum RhIG in all pregnancies) had a significantly lower HLA sensitization rate than D+ women (relative risk, 0.58; 95% confidence interval [CI], 0.40-0.83). When stratified by deliveries (one, two, three, or four or more), D– women not older than 40 were HLA sensitized less often than D+ women in every case. In contrast, a clear relationship between D type and HLA sensitization was not seen in older previously pregnant women whose childbearing years are presumed to have preceded the use of routine RhIG prophylaxis. In a multivariable logistic regression model, D– women not more than 40 years old remained significantly less likely to be HLA sensitized compared with D+ women after adjusting for parity, time from last pregnancy, lost pregnancies, and transfusions (odds ratio [OR], 0.55; 95% CI, 0.34-0.88).

Conclusion

Consistent with a nonspecific immunosuppressive effect of RhIG, younger previously pregnant D– women were less likely than previously pregnant D+ women to be HLA sensitized.

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