Apoptosis of purified CD4+ T cell subsets is dominated by cytokine deprivation and absence of other cells in new onset @entity6 XXXX .

@entity1 @entity2402 @entity6 @entity2047 @entity19 @entity5168 @entity3783 @entity10867 @entity1200 @entity204 @entity792
BACKGROUND: Regulatory T cells (Treg) play a significant role in immune homeostasis and self-tolerance. Excessive sensitivity of isolated Treg to apoptosis has been demonstrated in NOD @entity19 and @entity1 suffering of type 1 @entity6 , suggesting a possible role in the @entity1200 that underlies @entity792 . In this study the sensitivity to apoptosis was measured in T cells from new onset @entity6 females, comparing purified subsets to mixed cultures. PRINCIPAL FINDINGS: Apoptotic cells are short lived in vivo and @entity204 occurs primarily during isolation, manipulation and culture. Excessive susceptibility of @entity3783 (+) T cells to spontaneous apoptosis is characteristic of isolated subsets, @entity2402 when @entity204 is measured in mixed splenocyte cultures. In variance, @entity3783 (-) T cells display balanced sensitivity to apoptosis under both conditions. The isolation procedure removes soluble factors, @entity2047 playing a significant role in sustaining Treg viability. In addition, pro- and anti-apoptotic signals are transduced by cell-to-cell interactions: @entity5168 and @entity10867 protect @entity3783 (+) T cells from apoptosis, and in parallel sensitize na  ve effector cells to apoptosis. Treg viability is modulated both by other T cells and other subsets within mixed splenocyte cultures. Variations in sensitivity to apoptosis are often hindered by fast proliferation of viable cells, therefore cycling rates are mandatory to adequate interpretation of cell @entity204 assays. CONCLUSIONS: The sensitivity of purified Treg to apoptosis is dominated by cytokine deprivation and absence of cell-to-cell interactions, and deviate significantly from measurements in mixed populations. Balanced sensitivity of na  ve/effector and regulatory T cells to apoptosis in NOD @entity19 argues against the concept that differential susceptibility affects disease evolution and progression.
