Abstracts (complete list) - Wissenschaft Online

Benedikt Fritzsching, Eva Pauly, Nina Oberle, Navina Kuss, Katrin Hartmann, Peter
Ruf, Johannes Pöschl, Peter Krammer, Elisabeth Suri-Payer
Naive regulatory T cells: activation and apoptosis
sensitization of this novel Treg subpopulation during the
human neonatal period
CD4+CD25+FOXP3+ regulatory T cells (Treg) are potent immunosuppressive T cells.
Reduction of peripheral blood Treg numbers or function have been reported to be
associated with human autoimmune disease. However, the mechanisms responsible for
Treg -reduction are not clear. We have recently reported high sensitivity of the majority
of Treg towards CD95L-mediated apoptosis*. However, a Treg subpopulation remains
consistently apoptosis-resistant. Gene micro array and 6-color flow cytometry analysis
including FOXP3 revealed that naïve Treg constitute this so far neglected apoptosis
resistant Treg population. Naïve Treg show a phenotype similar to naïve conventional T
cells (CD45RA+, CD45RO-, partly CD31+, CCR6-, CD95-). Whereas naïve Treg
represent only a minority of Treg in adults, almost all cord blood Treg show such a
naïve phenotype. Here, we analyzed the postnatal activation status of Treg during the
first 28 days of healthy newborn infants. Whereas most conventional T cells showed a
naïve phenotype, Treg rapidly acquired an activated phenotype. Similar to adult Treg
these in vivo activated neonatal Treg showed an enhanced apoptosis sensitivity. Treg
activation and apoptosis sensitization occurred during the early postnatal expansion
phase of lymphocytes. This observation might reflect an important tolerance mechanism
for the control of the proliferating T cell compartment in the first weeks of a newborn´s
life.
Benedikt.Fritzsching@med.uni-heidelberg.de
* Fritzsching et al., Cutting Edge, Journal of Immunology l. 2005 Jul 1; 175(1):32-6