title: Tissue microchimerism is increased during pregnancy: a human autopsy study.
abstract: Microchimerism is the occurrence of small populations of cells with a different genetic background within an individual. Tissue microchimerism is considered to be primarily pregnancy-derived and is often studied relative to female-dominant autoimmune diseases, pregnancy complications, malignancies, response to injury, and transplantation outcomes. A particular distribution pattern of chimeric cells across various organs was recently described in a model of murine pregnancies. Our aim was to determine the frequency and distribution of tissue microchimerism across organs during and after pregnancy in humans. We performed in situ hybridization of the Y chromosome on paraffin-embedded autopsy samples of kidneys, livers, spleens, lungs, hearts and brains that were collected from 26 women who died while pregnant or within 1 month after delivery of a son. Frequencies of chimeric cells in various tissues were compared with those of a control group of non-pregnant women who had delivered sons. Tissue microchimerism occurred significantly more frequently in the lungs, spleens, livers, kidneys and hearts of pregnant women compared with non-pregnant women (all P < 0.01). We showed that some of the chimeric cells were CD3+ or CD34+. After correction for cell density, the lung was most chimeric (470 Y chromosome-positive nuclei per million nuclei scored), followed by the spleen (208 Y+/10(6) nuclei), liver (192 Y+/10(6) nuclei), kidney (135 Y+/10(6) nuclei), brain (85 Y+/10(6) nuclei) and heart (40 Y+/10(6) nuclei). Data from this unique study group of women who died while pregnant or shortly after delivery provide information about the number and physiologic distribution of chimeric cells in organs of pregnant women. We demonstrate that during pregnancy, a boost of chimeric cells is observed in women, with a distribution across organs, that parallels findings in mouse models.
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands e.c.rijnink@lumc.nl.
authors: Emilie C
authors: EC
authors: Rijnink
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Marlies E
authors: ME
authors: Penning
authors: Department of Medical Statistics and Bio-Informatics, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Ron
authors: R
authors: Wolterbeek
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Suzanne
authors: S
authors: Wilhelmus
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Malu
authors: M
authors: Zandbergen
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Sjoerd G
authors: SG
authors: van Duinen
authors: Department of Obstetrics & Gynaecology, Isala Clinics, Dokter van Heesweg 2, 8025 AB, Zwolle, The Netherlands.
authors: Joke
authors: J
authors: Schutte
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Jan A
authors: JA
authors: Bruijn
authors: Department of Pathology, Leiden University Medical Centre, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
authors: Ingeborg M
authors: IM
authors: Bajema
mesh_terms: D000293:Adolescent; D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D001344:Autopsy; D001921:Brain / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D046528:Chimerism; D041322:Chromosomes, Human, Y / Q000235:genetics*; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008875:Middle Aged; D011247:Pregnancy; D013154:Spleen / Q000378:metabolism; D055815:Young Adult
chemical_list: D018952:Antigens, CD34; D017252:CD3 Complex
keywords: female-dominant autoimmune diseases; fetal cells; maternal health; pregnancy; tissue microchimerism