Neonatal tumor necrosis factor alpha promotes diabetes in nonobese diabetic mice by CD154-independent antigen presentation to CD8(+) T cells

Abstract

Neonatal islet-specific expression of tumor necrosis factor (TNF)-α in nonobese diabetic mice promotes diabetes by provoking islet-infiltrating antigen-presenting cells to present islet peptides to autoreactive T cells. Here we show that TNF-α promotes autoaggression of both effector CD4+ and CD8+ T cells. Whereas CD8+ T cells are critical for diabetes progression, CD4+ T cells play a lesser role. TNF-α–mediated diabetes development was not dependent on CD154–CD40 signals or activated CD4+ T cells. Instead, it appears that TNF-α can promote cross-presentation of islet antigen to CD8+ T cells using a unique CD40–CD154-independent pathway. These data provide new insights into the mechanisms by which inflammatory stimuli can bypass CD154–CD40 immune regulatory signals and cause activation of autoreactive T cells.