Question

The factors that control lymphocyte lifespan are important, since lymphocytes undergo selective steps that must yield either death or longevity. While still poorly understood, among these factors are gene products of the bcl-2 family. Interestingly, some members of this gene family seem to promote longevity, whereas others seem to foster cell death. Recently, an investigator found that one of these genes, called bcl-z, had the following expression pattern among thymic and peripheral T cells shown in Table 1.

Table 1: Bcl-z expression in T cell subsets S face Phenotype Proportion expressing T cell Source CD4 CD8 CD4 CD8 CD4CD8 CD4 CD8 CD4-CD8* 100 20 18 Thymus Lymph Nodes

Do you think these data are most consistent with a lifespan-promoting
or lifespan-shortening role for bcl-z among thymocytes? Explain your
reasoning.

Outline one experiment to further probe your assertion about bcl-z’s role
in T-cell lifespan determination.

Answer 1