Maternal microchimerism is prevalent in cord blood in memory T cells and other cell subsets, and persists post-transplant

Oncoimmunology. 2017 Mar 31;6(5):e1311436. doi: 10.1080/2162402X.2017.1311436. eCollection 2017.

Abstract

Among reported advantages of umbilical cord blood (CB) in transplantation is lower leukemia relapse probability. Underlying cellular mechanisms of graft-vs.-leukemia (GVL) are thought to include a prominent role for T cells. Cells of the CB's mother, maternal microchimerism (MMc), were recently strongly, but indirectly, implicated in this GVL benefit. We assayed MMc directly and hypothesized benefit accrues from CB maternal T cells. MMc was quantified in 51 CBs and, within memory T, naïve T, B, NK cells, and monocytes in 27 CBs. Polymorphism-specific quantitative-PCR assays targeted maternal genotypes non-shared with CBs. Overall MMc was common and often at substantial levels. It was present in 52.9% of CB and in 33.3-55.6% of tested subsets. Remarkably, MMc quantities were greater in memory T cells than other subsets (p < 0.001). Expressed as genome equivalents (gEq) per 105 total gEq tested (gEq/105), memory T cell MMc averaged 850.2 gEq/105, while other subset mean quantities were 13.8-30.1 gEq/105. After adjustment for proportionality in CB, MMc remained 6-17 times greater in memory T, and 3-9 times greater in naïve T, vs. non-T-cell subsets. Further, CB-origin MMc was detected in vivo in a patient up to 6 mo post-transplantation, including among T cells. Overall, results revealed levels and phenotypes of CB MMc with potential relevance to CB transplantation and, more broadly, to offspring health.

Keywords: Cellular subsets; T cells; cord blood; graft-versus-leukemia; hematopoietic transplantation; maternal microchimerism.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't