Interleukin-7 modulates CD23 and HLA-DR expression on CD4+ T cells and promotes a Th-2 type citokine profile

The expression of CD23 on PHA-activated human PBT (peripheral blood T) cells of healthy donors was investigated. It appears that CD23 is expressed solely on activated CD4+ T cells. Cytofluorotometric analysis revealed that 6% of PHA-activated CD4+ T cells expressed CD23, while unstimulated CD4+ T cells express no detectable CD23. The addition of IL-7 (1000 U/ml) to activated CD4+ T cells resulted in a marked augmentation of CD23 expression (29%). CD23 expression was blocked by M20 and M26 mAbs, but no reduction was detected by anti-IL-2R (CD25) mAb. This suggests that IL-7 has a specific regulatory effect on CD23 expression independent of IL-2. Northern Blot analysis showed a marked increase of CD23 mRNA detected in PHA-activated CD4+ T cells plus IL-7. IL-7 was also able to upregulate the expression of HLA-DR on activated CD4+ T cells. Optimal HLA-DR and CD23 induction by IL-7 occurred at 48 and 72 h of culture. The addition of CHX revealed that the induction of CD23 and HLA-DR by IL-7 required intact protein synthesis. Furthermore, PHA activated CD4+ T cells cultured in the presence of IL-7 are polarized to a Th-2 pattern of cytokine production.