Prenatal tolerance induction: relationship between cell dose, marrow T-cells, chimerism, and tolerance

Area of Science:

• Immunology
• Transplantation Biology

Background:

• Deletional tolerance is influenced by self-antigen dose.
• Donor T cells are crucial for mixed chimera tolerance induction.

Purpose of the Study:

• To evaluate the impact of cell dose and marrow T cells on engraftment and tolerance after prenatal bone marrow transplantation.
• To determine if peripheral chimerism can predict prenatal immune tolerance.

Main Methods:

• Prenatal intraperitoneal bone marrow transplantation in mice using escalating doses of donor marrow.
• Postnatal assessment of peripheral chimerism via flow cytometry.
• Evaluation of tolerance through skin transplantation assays.

Main Results:

• High-level peripheral chimerism (>5.0 x 10^6 cells) led to donor-specific tolerance but increased graft-versus-host disease.
• T cell depletion reduced graft-versus-host disease at the expense of engraftment.
• Tolerance was dose-dependent on the level of peripheral chimerism, with >2% chimerism predicting long-term tolerance.

Conclusions:

• Peripheral chimerism is a reliable predictor of prenatal immune tolerance.
• Engraftment and tolerance induction are critically dependent on achieving sufficient peripheral chimerism.
• Optimizing cell dose is key to balancing tolerance induction and graft-versus-host disease.