Immature syngeneic dendritic cells potentiate tolerance to pancreatic islet allografts depleted of donor dendritic cells in microgravity culture condition.
BACKGROUND
Previously we showed that pancreatic islets cultured for seven days in rotating bioreactors survived for >100 days in allogeneic recipients without immunosuppression. This survival coincided with almost complete elimination of "passenger" donor dendritic cells (DCs). Herein, we examined the necessity of DCs in the generation of CD4+ CD25+ T regulatory (Treg) cells.


METHODS
Allogeneic fresh islets or islets cultured for three days in bioreactors were transplanted to streptozotocin-induced diabetic Balb/c(stat4 -/-) as well as signal transducers and activators of transcription (Stat)4-deficient Balb/c(stat6 -/-) or Balb/c(stat4 -/-) mice. Some Balb/c recipients of fresh islet allografts were also treated with a tolerogenic protocol of anti-CD40 Ligand MR1 mAb and CTLA4Ig.


RESULTS
Islet allografts cultured for three days in bioreactors survived >100 days in all Balb/c(stat4 -/-) recipients and in 56% of Balb/c(stat6 -/-) recipients, but in none of the Balb/c recipients; the same recipients rejected fresh islet allografts. Purified T cells from long-term surviving Balb/c(stat4 -/-) recipients failed to transfer tolerance to SCID recipients of donor-type fresh islet allografts. In contrast, MR1/CTLA4Ig therapy induced tolerance to fresh islet allografts and their T cells adoptively transferred tolerance. When Balb/c or Balb/c(stat4 -/-) recipients of bioreactor-cultured islets were injected intravenously with immature syngeneic DCs, they became tolerant and developed potent alloantigen-specific CD4+ CD25+ Treg cells expressing Foxp3.


CONCLUSIONS
Allogeneic islets depleted of donor DCs by culture in bioreactors have almost twofold better acceptance in Balb/c(stat4 -/-) than in Balb/c(stat6 -/-) mice, but lack Treg cells. Additional injection of host immature DCs improves tolerance in Balb/c and Balb/c(stat4 -/-) recipients by inducing potent CD4+ CD25+ Treg cells.
Stepkowski
Stanislaw M
SM
Division of Immunology and Organ Transplantation, University of Texas Medical School at Houston, Houston, TX 77030, USA. stanislaw.stepkowski@uth.tmc.edu
Phan
Tammy
T
Zhang
Huimin
H
Bilinski
Szczepan
S
Kloc
Malgorzata
M
Qi
Yuhua
Y
Katz
Stephen M
SM
Rutzky
Lynne P
LP
D000818:Animals; D019149:Bioreactors; D015704:CD4 Antigens / Q000032:analysis; D046508:Culture Techniques; D003713:Dendritic Cells / Q000276:immunology*; D006085:Graft Survival / Q000235:genetics; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D007515:Islets of Langerhans / Q000166:cytology / Q000276:immunology; D016381:Islets of Langerhans Transplantation / Q000276:immunology*; D051379:Mice; D008817:Mice, Mutant Strains; D050797:STAT4 Transcription Factor / Q000172:deficiency / Q000235:genetics; D050800:STAT6 Transcription Factor / Q000172:deficiency / Q000235:genetics; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D014019:Tissue Donors; D023001:Transplantation Tolerance; D014184:Transplantation, Homologous; D014893:Weightlessness
D015704:CD4 Antigens; D053645:Interleukin-2 Receptor alpha Subunit; D050797:STAT4 Transcription Factor; D050800:STAT6 Transcription Factor; C494091:Stat4 protein, mouse; C494100:Stat6 protein, mouse