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Immunomodulation by blood transfusions
D L Roelen1, J J van Rood, A Brand
1Leiden University Medical Center, Dept. Immunohaematology and Blood Transfusion, The Netherlands.
Vox Sanguinis
|August 12, 2000
Summary
Blood transfusions can induce either immune tolerance or immunization. HLA-DR compatibility in transfusions promotes tolerance, potentially via CD4+ regulatory T cells, which may downregulate alloimmune responses.
Area of Science:
- Immunology
- Transfusion Medicine
- Transplantation
Background:
- Blood transfusions can paradoxically induce immune tolerance or immunization.
- Immunization involves HLA alloantibody induction and T cell activation.
- Tolerance is suggested by improved graft survival in transfused recipients.
Purpose of the Study:
- To investigate the immunological mechanisms behind transfusion-induced immune tolerance.
- To explore the role of HLA compatibility in modulating alloimmune responses.
- To test the hypothesis that CD4+ regulatory T cells mediate tolerance.
Main Methods:
- Analysis of HLA compatibility between transfusion donors and recipients.
- Investigating the role of Th2 responses and non-professional antigen presentation.
- Identifying CD4+ T cells specific for allopeptides in the context of self-HLA-DR.
Main Results:
- Transfusions sharing HLA-DR antigens induce tolerance, while mismatched transfusions lead to immunization.
- Preliminary data show CD4+ T cells recognizing allopeptides in self-HLA-DR context can downregulate alloimmune responses.
- Evidence suggests a central role for CD4+ regulatory T cells in tolerance induction.
Conclusions:
- HLA-DR compatibility is a key factor in transfusion outcomes.
- CD4+ regulatory T cells recognizing allopeptides in a self-HLA-DR context may be responsible for tolerance.
- Further studies on transplant patients are needed to confirm the role of these regulatory T cells.