Activated and "memory" phenotype of circulating T lymphocytes in intrauterine life.
We examined the expression of T cell markers in the peripheral blood of five immunologically normal human fetuses at 18-20 weeks of gestational age. The distribution of T cells expressing CD1, CD3, CD4, CD8, CD56, and the alpha/beta and gamma/delta receptors for antigen was comparable to that of newborns and normal adults, except for the absence of gamma/delta cells expressing the delta TCS-1 epitope. The V beta repertoire, as evaluated by two-color flow cytometry using mAbs to specific V beta families, was also comparable to that of adult samples. A significant fraction (8.9 to 16.4%) of fetal CD3+ T cells expressed the alpha chain of IL-2R (CD25) in the absence of HLA-DR; this suggests that antigenic stimuli trigger, during intrauterine life, an unusual pathway of T cell activation. Consistent with this, 7 to 27% of fetal T cells were found to express the CD45R0 marker of "memory" cells.
Paganelli
R
R
Department of Allergy and Clinical Immunology, University La Sapienza, Rome, Italy.
Cherchi
M
M
Scala
E
E
Maggi
E
E
Carbonari
M
M
Ferranti
G
G
Dell'Anna
L
L
Pachì
A
A
Fiorilli
M
M
D015703:Antigens, CD / Q000032:analysis; D015415:Biomarkers; D002454:Cell Differentiation; D005333:Fetus / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D015703:Antigens, CD; D015415:Biomarkers; D011948:Receptors, Antigen, T-Cell