Changing patterns of dominant TCR usage with maturation of an EBV-specificcytotoxic T cell response

Infection crith EBV provides a unique opportunity to follow the human CD8() T cell response to a persistent, genetically stable agent from the primar y phase, as seen in infectious mononucleosis (IR I) patients, into long-ter m memory, This study focuses on the response to an immunodominant HLA-A2.01 -restricted epitope, GLCTLVAML, from the EBV-lytic cycle Ag BMLF1. TCR anal ysis of the highly amplified primary response to this epitope revealed mark edly oligoclonal receptor usage among in vitro-derived clones, with similar clonotypes dominant in all three IM patients studied. Direct staining of I M T cell preparations with the A2.01/GLCTLVAML tetramer linked this oligocl onal epitope-specific response with appropriate V beta subset expansions in the patients' blood. These patients were studied again >2 years later, at which time TCR analysis of in vitro-reactivated clones suggested that rare clonotypes within the primary response had now come to dominate memory. Fiv e additional A2.01-positive IRI patients were studied prospectively for V b eta subset representation within primary and memory epitope-specific popula tions as identified by tetramer staining. In each case, the primary respons e contained large V beta2, V beta 16, or V beta 22 components, and in three of five cases the originally dominant V beta was represented very poorly, if at all, in memory. We conclude 1) that an EBV epitope-specific primary r esponse large enough to account for up to 10% CD8(+) T cells in IM blood ma g nevertheless be dominated by just a felv highly expanded clonotypes, and 2) that with persistent viral challenge such dominant T cell clonotypes may be lost and replaced by others in memory.