In vitro immunization with a recombinant antigen carrying the HIV-1 RT248-262 determinant inserted at different locations results in altered TCRVB region usage

Immunodominance or cripticity of a peptide-borne determinant may be influen ced by the protein context in which the epitope is embedded. In this frame, we previously showed that certain human T cell clones, derived from differ ent donors, may differentially recognize the RT248-262 helper determinant d epending on whet her it is provided to the presenting cells as a synthetic peptide or as a recombinant carrier protein to which the sequence of intere st is fused. We now report that, upon in vitro immunization of human PBL wi th autologous APC, the epitope-specific TCRVB repertoire obtained when sele ction is applied by pulsing the APC with the cognate synthetic peptide is d ifferent from that found when a recombinant protein is used in which the an tigenic sequence is placed at either a N-terminal or C-terminal location of the GST carrier. As the TCRVB distribution is not a function of the APC us ed, we propose that processing of different recombinant molecules containin g the same epitope may generate MHC/peptide complexes which, being antigeni cally diverse, may recruit: distinct: TCR specificities. These findings may be relevant for evaluating and predicting the immunogenic potential of sub unit vaccines based on synthetic peptides or on recombinant proteins as com pared to the native antigen. (C) American Society for Histocompatibility an d Immunogenetics, 1999. Published by Elsevier Science Inc.