Susceptibility of different subsets of immature thymocytes to apoptosis induced by anti-TCRmAb

To analysis the susceptibility of different subsets of immature mice thymocytes to apoptosis induced by anti-TCRmAbs in vitro apoptosis was induced in unfractionated mice thymocytes by anti-TCRmAb. In Vivo apoptosis was induced in BALB/c mice by anti-TCR mAb, and thymocytes were examined by FACS. Results showed that CD4+ CD8+ DP thymocytes and CD4- CD8+ CD3- thymocytes were equally sensitive to apoptosis after treatment with the anti-TCR mAb. In sharp contrast, the early migrants or precursor containing thymocytes which are CD4- CD8- CD3- TN have a lower spontaneous apoptosis rate and were relatively resistant to the anti-TCR mAb. The findings showed a breakpoint in thymocyte sensitivity to apoptosis which occurs after the onset of CD4- CD8+ CD3 expression, suggesting that susceptibility of thymocytes to apoptosis is developmentally regulated