PTD-J-X: To Elicit Humoral and Cellular Immunity as Will

It is conventionally pictured that extracellular antigens are engulfed by antigen presenting cells (APCs) via endocytosis. Then the antigens are digested in lysoendosome to produce peptide epitopes which are loaded to class II major histocompatibility complex (MHC-II) before recycling back onto cell membrane. On the other hand, intracellular antigens are processed by proteasome and the peptide epitope products are transported into endoplasmic reticulum where these epitopes are assembled into de novo synthesized MHC-I molecules (Figure 1). Recently, a PTD-J-X antigen presenting model which was composed of a protein transduction domain (PTD), the cell penetrating peptide of HIV Tat protein, a J-domain of Hsp40 and an X polypeptide was introduced. The X polypeptide was an assortment of either Th2 epitopes (MHC-II associating peptides) and B epitopes, which could associate with B cell receptor, or Th1 epitopes (MHC-II associating peptides) plus Tc epitopes MHC-I associating peptides [1].