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Immunological tolerance in an HLA non-identical chimeric twin
H E Viëtor1, B C Hamel, S P van Bree
1Department of Human Genetics, University Hospital Nijmegen, Nijmegen, The Netherlands. h.vietor@antrg.azn.nl
Human Immunology
|February 26, 2000
Summary
Blood group chimeras, twins sharing blood types, show no immune rejection despite genetic differences. This case highlights the potential for natural immunological tolerance in humans.
Area of Science:
- Human immunology
- Genetics
- Twin studies
Background:
- Blood group chimerism, where individuals share blood types, presents a unique model for studying human immune tolerance.
- Detailed immunological investigations of blood group chimeras are scarce, despite the condition being less rare than previously thought.
Observation:
- A case of secondary chimerism involving dizygotic twins of opposite genders was investigated.
- Karyotyping confirmed the sex of each twin (46,XY for the boy and 46,XX for the girl).
- Molecular HLA typing identified disparities in HLA-DR, DQ, and DP loci between the siblings.
Findings:
- Despite significant Human Leukocyte Antigen (HLA) disparities, mixed lymphocyte culture (MLC) assays demonstrated a complete absence of mutual alloreactivity.
- This indicates a state of robust immunological tolerance between the chimeras.
Implications:
- This case provides valuable insights into the mechanisms of natural immunological tolerance in humans.
- Understanding tolerance in chimeras could inform strategies for transplantation and autoimmune disease treatment.
- Further research into blood group chimerism is warranted to explore its full potential in immunological studies.