TCR sequencing will be performed using multiplex PCR system to amplify rearranged TCRbeta DNA using primers specific to a functional TCR Vbeta segment as previously described. Genomic templates will be amplified and observed relative abundance of Vbeta 5.1 family TCR clonotypes will be inferred from sequence data using an expectation maximization algorithm. CDR3 motifs as defined by the international ImMunoGeneTics information system (IMGT) will be predicted based on DNA sequences. For every read, best sequence alignment against reference sequences will be computed and reads with low quality scores will be discarded. To exclude unspecific T cells due to sorting impurities and/or stimulation background, antigen-specific clones with frequencies below 1 percent will be neglected.