Immature and maturation-resistant human dendritic cells generated from bone marrow require two stimulations to induce T cell anergy in vitro.

Immature dendritic cells (DC) represent potential clinical tools
for tolerogenic cellular immunotherapy in both transplantation and
autoimmunity. A major drawback in vivo is their potential to mature
during infections or inflammation, which would convert their
tolerogenicity into immunogenicity. The generation of immature DC
from human bone marrow (BM) by low doses of GM-CSF (lowGM) in the
absence of IL-4 under GMP conditions create DC resistant to
maturation, detected by surface marker expression and primary
stimulation by allogeneic T cells. This resistence could not be
observed for BM-derived DC generated with high doses of GM-CSF plus
IL-4 (highGM/4), although both DC types induced primary allogeneic
T cell anergy in vitro. The estabishment of the anergic state
requires two subsequent stimulations by immature DC. Anergy
induction was more profound with lowGM-DC due to their maturation
resistance. Together, we show the generation of immature,
maturation-resistant lowGM-DC for potential clinical use in
transplant rejection and propose a two-step-model of T cell anergy
induction by immature DC.