Direct Demonstration of the CD27 Molecule Involved in the Negative Regulatory Effect on T Cell Activation

CD27 is a member of the nerve growth factor/tumor necrosis factor receptor family and appears to play an important role in the process of T cell activation. We have previously shown that perturbation of the CD27 molecule by anti-IA4 (CD27) mAb inhibits T cell proliferation induced by various stimuli. To further determine the molecular basis of this inhibition of T cell proliferation by anti-1A4 mAb, we have established CD27-transfectant lines. Introduction of the human CD27 cDNA to ovalbumin-specific I-Ad-restricted murine T cell hybridomas significantly reduced their antigen-specific IL-2 production. In addition, treatment of these human CD27 transfectants with an anti-CD27 mAb (anti-1A4) further reduced their IL-2 production. These results provide direct evidence that CD27 plays a crucial role in the process of T cell activation.