title: Heterogeneity in fetal immunocompetence during the second trimester of gestation. Implications for treatment of nonimmune genetic disorders by in utero transplantation.
abstract: OBJECTIVE
  To address the role that alloreactivity may play and better define the window for histoincompatible stem cell transplantation in utero.
  
  
  METHODS
  We studied 9 fetal blood specimens obtained by cardiocentesis during elective abortions in the second trimester by multicolor flow cytometry and in vitro stimulation.
  
  
  RESULTS
  Lymphocytes ranged from adult levels (3/9) to >90% leukocytes. Six specimens had T cells within adult range. T cells in the other specimens were reduced, while B cells were conversely elevated. This variability did not correlate with gestational age, or leukocyte composition. Following 4 h of mitogenesis, fetal CD4+ and CD8+ T cells from 1 of 5 specimens showed a response similar to that of maternal T cells, while the other 4 specimens showed a diminished response (0.3 +/- 0.2-fold). This heterogeneity did not correlate with gestational age, or lymphocyte subset distribution. Following 18 h of in vitro mitogenesis, fetal T cells from 2 specimens showed a response similar to that of maternal T cells (0.8 +/- 0.2-fold). Despite that, one specimen gave a 3-fold greater response in a one-way mixed lymphocyte reaction vs. maternal cells compared to the other specimen.
  
  
  CONCLUSIONS
  We determine that fetal immunocompetence differs greatly during the second trimester and assessment of host vs. donor reactivity prior to in utero transplantation is likely to potentiate more favorable outcomes.
authors.affiliation: Division of Infectious Disease and Immunology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA. tsed01@med.nyu.edu
authors.forename: Doris B
authors.initials: DB
authors.lastname: Tse
authors.forename: Elbert
authors.initials: E
authors.lastname: Ching
authors.forename: Nora
authors.initials: N
authors.lastname: Yousefzadeh
authors.forename: Hank
authors.initials: H
authors.lastname: Roque
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Young
mesh_terms: D000917:Antibody Formation; D001772:Blood Cell Count; D005260:Female; D005312:Fetal Blood; D046128:Fetal Therapies; D005333:Fetus / Q000276:immunology*; D005434:Flow Cytometry; D030342:Genetic Diseases, Inborn / Q000196:embryology / Q000601:surgery; D006648:Histocompatibility; D006801:Humans; D007121:Immunocompetence; D007519:Isoantigens / Q000276:immunology; D007958:Leukocyte Count; D016131:Lymphocyte Subsets / Q000166:cytology; D008938:Mitosis; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D033581:Stem Cell Transplantation; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D007519:Isoantigens