mEmerald and Fusion Red-tagged F-tractin, an acting binding peptide derived from the Itpka protein from rat was generated by cloning into a Clontech-style vector containing the advanced EGFP variant Emerald (F64L, S65T, S72A, N149K, M153T, I167T, A206K).
However, despite an MHC class II restricted peptide derived from the fusion region of EWS-FLI1 that is able to initiate a CD4+ T-cell response (Meyer-Wentrup et al, 2005), no immunogenic ET-specific MHC class I binding peptide derived from this fusion region has been identified yet.
We screened for specific hoefavidin binding peptides derived from the C-terminal region and two peptides were obtained that bind a truncated form of hoefavidin (lacking the last 10 amino acids) with dissociation constants of 10−5 M.
Upon binding peptides derived from endosomes or the extracellular milieu, the intact MHC II-peptide complex is displayed at the cell surface of antigen presenting cells (APC) for surveillance by CD4+ T-cells [1].
For example, Garcia et al. [37] report an HLA-DRB1*0401 binding peptide (WGENDTDVFVLNNTR) and 12 additional binding peptides derived from that peptide by replacing one of the amino acid in (WGENDTDVFVLNNTR) sequence with Glycine and experimentally determining the binding affinity of the new peptide.
In this way, HLA-E is highly selective in binding peptides derived from HLA class I leader sequences, and this condition regulates its expression on the cell surface [ 32].
The Her-2/neu oncogene is amplified in approximately 40% of breast cancers, and Her-2/neu-specific T cell responses have been observed in patients vaccinated with major histocompatibility (MHC) class II binding peptides derived from Her-2/neu [ 11].
Thus, individuals carrying certain HLA alleles capable of binding peptides derived from bcr-abl fusion transcripts can in principle be considered to have a biological advantage in fighting the disease over individuals lacking these particular HLA alleles.
Although the direct contribution of MHC genes to the immunological fitness of animals is still unclear, the relatively high genetic diversity of the MHC reflects the abundance in repertoire of binding peptides, derived from pathogens.
With regard to epithelial cancers, Murphy and colleagues used DCs pulsed with HLA-A2 binding peptides derived from prostate-specific membrane antigen to treat patients with prostate cancer and observed significant clinical responses in 8 out of 33 vaccinated patients [ 18], and in a subset of these responders, cytokine secretion and CTL activity was detected against the immunizing peptide [ 19].
However, to reduce the potential risk of destructive autoimmune reactions, it seems favourable to use groups of well-defined human leucocyte antigen (HLA) class I binding peptides derived from glioma-associated antigens that have been demonstrated to serve as target structures for T cells rather than introducing undefined mixtures of antigens to DCs.
