Differential expansion and survival of high and low avidity cytotoxic T cell populations during the immune response to a viral infection

The importance of high avidity CTL for the effective clearance of viral inf ections is now well established. Thus one would predict that the preferenti al activation and expansion of high avidity CTL following viral challenge a nd retention of these cells in the memory pool would be optimal for the imm une response. However, whether this actually occurs during the immune respo nse to viral infection is unknown. In this report I have analyzed the avidi ty of the CTL specific for the OVA(257-264) peptide during acute infection with a recombinant vaccinia expressing ovalbumin and in the memory populati on. I have found that the relative ratio of high and low avidity CTL varies over the course of an immune response. Thus CTL avidity is an important fa ctor in the expansion and survival of CTL in vivo. (C) 2000 Academic Press.