Cross-presentation of phage particle antigen in MHC class II and endoplasmic reticulum marker-positive compartments

Abstract

It has been shown that exogenous antigens can access the MHC class I pathway of professional antigen-processing cells. However, details as to how the MHC class Ipeptide complex forms in the presentation pathway are still poorly understood. Here we used MHC class I-peptide-specific antibodies to investigate the formation and intracellular location of class I-peptide complexes in macrophages. We observed that the formation of class I-peptide complexes occurs within a few hours and lasts for another few hours on the cell surface of macrophages following loading with filamentous phage particles. The class I-peptide complexes in the process were colocalized with MHC class II molecules and endocytic system markers. Moreover, endosomal compartments containing class I-peptide complexes were found within intracellular organelles stained by DiOC6 and calnexin. In addition, the crosspresentation of phage particles was transporter associated with antigen processing (TAP)-dependent and sensitive to proteasome inhibitors and NH 4 Cl. These data suggest that endocytosed phage particles may be processed and cross-presented in organelles positive for phagosome and endoplasmic reticulum (ER) markers via a classical ER MHC class I loading mechanism.

The Use of Filamentous Bacteriophagefdto Deliver MAGE-A10 or MAGE-A3 HLA-A2-Restricted Peptides and to Induce Strong Antitumor CTL Responses

“…The mechanisms underlying the efficacy of engineered virions to generate specific and potent antitumor CTLs are currently unknown and are under investigation in our laboratory. It has been previously described by others and by us that filamentous bacteriophage fd are taken up and processed by MHC class I and class II pathways (38,39). This might explain, at least in part, the ability of virions displaying foreign T cell epitopes to elicit potent Th cell-dependent CTL responses.…”

Overcoming Immune Tolerance Against Multiple Myeloma With Lentiviral Calnexin-engineered Dendritic Cells

“…28,38 CNX may also enhance cross-presentation of exogenous antigens through the class I major histocompatibility complex pathway. 39 MM patients' DCs presenting cancer antigens do not induce an effective T helper or cytotoxic T-lymphocyte response against cancer cells. LV-CNX-modified MM DCs, by contrast, effectively boosted cytokine production in both CD4 and CD8 T cells coupled with increased cancer cell killing activity.…”

Carbon monoxide impairs mitochondria‐dependent endosomal maturation and antigen presentation in dendritic cells

“…As both soluble antigens and Salmonella are drastically smaller than these beads (endosome volume: ß0.2-1.3 μm 3 ; Salmonella volume: ß2.0-4.0 μm 3 ; beads volume: ß14.14 μm 3 ), it is likely that CO only blocks maturation of small endo/phagosomes. Along these lines, it has been recently shown that particle size determines the composition of the endo/phagosomal membrane in DCs because 3 μm-beads possess both ER-derived proteins in their membranes (due to ERmediated phagocytosis) and also a remarkable expression of both MHC-I and MHC-II molecules [83][84][85][86][87][88][89][90][91]. This phagosome is known as the ERgosome (Fig.…”