Immunological implications of pregnancy-induced microchimerism

Abstract

Immunological identity is traditionally defined by genetically encoded antigens, with equal maternal and paternal contributions as a result of Mendelian inheritance. However, vertically transferred maternal cells also persist in individuals at very low levels throughout postnatal development. Reciprocally, mothers are seeded during pregnancy with genetically foreign fetal cells that persist long after parturition. Recent findings suggest that these microchimeric cells expressing noninherited familially relevant antigenic traits are not accidental souvenirs of pregnancy, but are purposefully retained within mothers and their offspring to promote genetic fitness by improving the outcome of future pregnancies. Here, we discuss the immunological implications, benefits and potential consequences of individuals being constitutively chimeric with a biologically active ‘microchiome’ of genetically foreign cells.

British HIV Association guidelines for the management of HIV in pregnancy and postpartum 2018

“…Mother‐to‐infant trafficking of maternal cells (including CD4 cells) occurs and these cells can persist in the infant circulation after birth . Although the relevance of this process in HIV transmission is not known, it has recently been suggested to have implications for vertical transmission of HBV .…”

Forward and reverse inheritance — the yin and the yang

“…Naturally acquired microchimerism can be tissue-specific or haematopoietic, and harbouring multiple microchimeric ‘grafts’ across generations in women is of special interest, as highlighted by experimental studies 10 . Much can be learned from elucidating the long-term consequences of forward and reverse inheritance; in terms of both the benefits and the risks that can be accrued from our immigrant cell populations, acquired as a natural form of ‘mini-gene transfer’.…”

Memory T‐cell exhaustion and tolerance in transplantation

“…10 However, the persistence of fetal microchimeric cells expressing disparate MHC molecules have also been shown to be the target of maternal alloimmunity. 10 However, the persistence of fetal microchimeric cells expressing disparate MHC molecules have also been shown to be the target of maternal alloimmunity.…”

“…10 However, the persistence of fetal microchimeric cells expressing disparate MHC molecules have also been shown to be the target of maternal alloimmunity. 10 Sensitization to familial antigens is an important area of ongoing research, as living donor renal transplants are often donated by family members. 10 Sensitization to familial antigens is an important area of ongoing research, as living donor renal transplants are often donated by family members.…”