Comparative analysis of CD8 expressed on mature CD4+CD8+T cell clones cultured with IL-4 and that on CD8+T cell clones: implication for functional significance of CD8β

摘要

Interleukln (IL-4) can induce CD8 expression on mature CD4+T cells. To study this phenomenon in more detail, we characterized CDS expressed on IL-4-lnduced CD4+CD8+(double positive) T cell clones in comparison with that on CD8+T cell clones. Using 2ST8–5H7 mAb that detects CD8βexpression, we found that double positive T cell clones isolated with IL-4 express CD8αbut notβ, in contrast to CD8+CTL cell clones, which express both chains of CD8. Northern blot analysis revealed that these double positive clones expressed CD8αbut notβmRNA, indicating that CD8αandβare Independently regulated at the pre-translatlonal level. Immunopreclpitation experiments showed that CD8 expressed on a representative IL-4-lnduced double positive T cell clone consists mainly of homodimers of a single 34 kd protein of CD8α. The amount of multimers detected from this clone was much less than that from a CD8+CTL clone. These results suggest that persistent expression of CD8βIs specific for the CD8+lineage and may be involved in polymerization and stabilization of CD8 which enhances the efficiency of class l-restrlcted antigen r