Modification of host dendritic cells by microchimerism-derived extracellular vesicles generates split tolerance.
Maternal microchimerism (MMc) has been associated with development of allospecific transplant tolerance, antitumor immunity, and cross-generational reproductive fitness, but its mode of action is unknown. We found in a murine model that MMc caused exposure to the noninherited maternal antigens in all offspring, but in some, MMc magnitude was enough to cause membrane alloantigen acquisition (mAAQ; "cross-dressing") of host dendritic cells (DCs). Extracellular vesicle (EV)-enriched serum fractions from mAAQ+, but not from non-mAAQ, mice reproduced the DC cross-dressing phenomenon in vitro. In vivo, mAAQ was associated with increased expression of immune modulators PD-L1 (programmed death-ligand 1) and CD86 by myeloid DCs (mDCs) and decreased presentation of allopeptide+self-MHC complexes, along with increased PD-L1, on plasmacytoid DCs (pDCs). Remarkably, both serum EV-enriched fractions and membrane microdomains containing the acquired MHC alloantigens included CD86, but completely excluded PD-L1. In contrast, EV-enriched fractions and microdomains containing allopeptide+self-MHC did not exclude PD-L1. Adoptive transfer of allospecific transgenic CD4 T cells revealed a "split tolerance" status in mAAQ+ mice: T cells recognizing intact acquired MHC alloantigens proliferated, whereas those responding to allopeptide+self-MHC did not. Using isolated pDCs and mDCs for in vitro culture with allopeptide+self-MHC-specific CD4 T cells, we could replicate their normal activation in non-mAAQ mice, and PD-L1-dependent anergy in mAAQ+ hosts. We propose that EVs provide a physiologic link between microchimerism and split tolerance, with implications for tumor immunity, transplantation, autoimmunity, and reproductive success.
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Related Subject Headings
- T-Cell Antigen Receptor Specificity
- Pregnancy
- Models, Immunological
- Mice, Transgenic
- Mice, Inbred C57BL
- Mice
- Maternal-Fetal Exchange
- Male
- Isoantigens
- Immune Tolerance
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- T-Cell Antigen Receptor Specificity
- Pregnancy
- Models, Immunological
- Mice, Transgenic
- Mice, Inbred C57BL
- Mice
- Maternal-Fetal Exchange
- Male
- Isoantigens
- Immune Tolerance