Double Negative (CD3(+)4(−)8(−)) TCRαβ Splenic Cells from Young NOD Mice Provide Long-Lasting Protection against Type 1 Diabetes

BACKGROUND: Double negative CD3(+)4(−)8(−) TCRαβ splenic cells (DNCD3) can suppress the immune responses to allo and xenografts, infectious agents, tumors, and some autoimmune disorders. However, little is known about their role in autoimmune diabetes, a disease characterized by the reduction of insulin production subsequent to destruction of pancreatic β-cells by a polyclonal population of self-reactive T-cells. Herein, we analyzed the function and phenotype of DNCD3 splenic cells in young NOD mice predisposed to several autoimmune disorders among which, the human-like autoimmune diabetes. METHODOLOGY/PRINCIPAL FINDINGS: DNCD3 splenic cells from young NOD mice (1) provided long-lasting protection against diabetes transfer in NOD/Scid immunodeficient mice, (2) proliferated and differentiated in the spleen and pancreas of NOD/Scid mice and pre-diabetic NOD mice into IL-10-secreting T(R)-1 like cells in a Th2-like environment, and (3) their anti-diabetogenic phenotype is CD3(+)(CD4(−)CD8(−))CD28(+)CD69(+)CD25(low) Foxp3(−) iCTLA-4(−)TCRαβ(+) with a predominant Vβ13 gene usage. CONCLUSIONS/SIGNIFICANCE: These findings delineate a new T regulatory component in autoimmune diabetes apart from that of NKT and CD4(+)CD25(high) Foxp3(+)T-regulatory cells. DNCD3 splenic cells could be potentially manipulated towards the development of autologous cell therapies in autoimmune diabetes.