Analysis of the susceptibility of CD57+ T cells to CD3-mediated apoptosis

Abstract

Summary After stimulation with anti-CD3 antibody in vitro, CD57+ T cells showed a greater susceptibility to apoptosis than CD57–αβT cell receptor (TCR)+ T cells (regular αβ T cells). The apoptotic fraction of CD57+ T cells showed an increased production of active caspase-3. An increase in both Fas expression and Fas-ligand (FasL) production was also observed in CD57+ T cells, whereas the expression of survivin was suppressed in CD57+ T cells compared to that of regular αβ T cells. CD57+ T cells display a biased expansion of a few Vβ T cell fractions in individuals, but such Vβ T cells were not specifically susceptible to CD3-mediated apoptosis. The TCR expression level of CD57+ T cells was much lower than that of regular T cells and anti-TCR antibody stimulation induced a smaller apoptotic proportion of CD57+ T cells than did anti-CD3 antibody. Although the CD3ɛ expression levels were similar in both T cell subsets, the CD3ζ level of CD57+ T cells was significantly higher than that of regular T cells. These results suggest that several apoptotic and anti-apoptotic molecules are involved in the CD3-induced apoptosis of CD57+ T cells and raise the possibility that the imbalance in expression of the CD3ɛ and CD3ζ chains may also contribute to the susceptibility of CD57+ T cells to undergo apoptosis.