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Human mid‐gestation amniotic fluid contains interleukin‐16 bioactivity
Author(s) -
Thornton Catherine A.,
Holloway Judith A.,
Shute Janis K.,
Holloway John W.,
Diaper Norma D.,
Warner John O.
Publication year - 2009
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2008.02903.x
Subject(s) - amniotic fluid , fetus , gestation , pregnancy , placenta , medicine , endocrinology , biology , lamina propria , andrology , epithelium , genetics
Summary CD4‐positive cells are detectable in the human fetal gastrointestinal tract from 11 weeks of gestation. Interleukin‐16 (IL‐16) is a chemoattractant for CD4 + cells and, via fetal swallowing of amniotic fluid, could mediate the influx of CD4 + cells into the fetal gut. We have shown that IL‐16 was detectable in human amniotic fluid at 16–18 weeks of gestation (mid‐pregnancy) but was not detectable at term (late pregnancy; > 37 weeks of gestation). Similarly, mid‐pregnancy, but not late pregnancy, amniotic fluid contained chemotactic activity for CD4 + T cells, this activity was reduced by 58% in the presence of a neutralizing anti‐IL‐16 antibody. The levels of IL‐16 in fetal plasma at 16–24 weeks of gestation were very high, and decreased significantly by 25–36 weeks but at > 37 weeks remained significantly higher than adult levels. IL‐16 transcripts were detectable in whole tissue extracts of fetal gut, skin and placenta but not in amniocytes, and IL‐16 immunoreactivity was detectable in cells within the lamina propria of the fetal gut and within the skin, where it was associated with the basement membrane. Neither IL‐16 levels nor chemotactic activity for CD4 + T cells in mid‐pregnancy amniotic fluid was related to atopic outcomes at 1 year of age. IL‐16 might have an important role in the early development of the human immune system and/or in regulating fetal and maternal immunological responsiveness during pregnancy.