Dela Cruz Jay Soriano, Trinh Kamh Ryan, Chen Hsiao Wen, Ribas Antoni, Morrison Sherie L, Penichet Manuel L
Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles (UCLA), Los Angeles, CA 90095, USA.
Mol Immunol. 2006 Feb;43(6):667-76. doi: 10.1016/j.molimm.2005.04.007.
HER2/neu, a transmembrane glycoprotein overexpressed in several types of human cancers, is a potential target for active immunotherapy. However, this protein and especially its extracellular domain (ECD(HER2)), is weakly immunogenic and is poorly processed by dendritic cells (DCs). Previously, we showed that anti-HER2/neu IgG3-(IL-2) and anti-HER2/neu IgG3-(GM-CSF) fusion proteins can enhance the immunogenicity of ECD(HER2) in mice, and that the non-covalent physical association between each antibody fusion proteins and ECD(HER2) was critical to elicit optimal protective immunity against HER2/neu expressing tumors. We now use the professional antigen-presenting DCs to investigate the effect of the antibody fusion protein binding to ECD(HER2) on its trafficking and presentation. We found that when the extracellular domain of HER2/neu fused to ovalbumin (OVA-ECD(HER2)) is bound by HER2/neu-specific antibody-(IL-2) or antibody-(GM-CSF) fusion proteins, the bound antigen is more efficiently processed by murine bone-marrow-derived dendritic cells (BMDCs) and presented to OVA-specific T-cells than the unbound OVA-ECD(HER2). We also found that ECD(HER2) bound by anti-HER2/neu IgG3-(IL-2) is very efficiently internalized and that the internalized ECD(HER2) is not retained in the early endosomal compartments but traffics to the antigen-processing compartments. These results are consistent with our earlier in vivo studies and suggest that both antibody-(IL-2) and antibody-(GM-CSF) fusion proteins can be used to enhance the immune response to poorly immunogenic antigens including tumor-associated antigens (TAAs).
HER2/neu是一种在多种人类癌症中过表达的跨膜糖蛋白，是主动免疫疗法的潜在靶点。然而，这种蛋白，尤其是其细胞外结构域（ECD(HER2)），免疫原性较弱，树突状细胞（DCs）对其处理效果不佳。此前，我们发现抗HER2/neu IgG3-(IL-2)和抗HER2/neu IgG3-(GM-CSF)融合蛋白可增强小鼠体内ECD(HER2)的免疫原性，且每种抗体融合蛋白与ECD(HER2)之间的非共价物理结合对于引发针对表达HER2/neu的肿瘤的最佳保护性免疫至关重要。我们现在使用专业的抗原呈递树突状细胞来研究抗体融合蛋白与ECD(HER2)结合对其运输和呈递的影响。我们发现，当与卵清蛋白融合的HER2/neu细胞外结构域（OVA-ECD(HER2)）与HER2/neu特异性抗体-(IL-2)或抗体-(GM-CSF)融合蛋白结合时，与未结合的OVA-ECD(HER2)相比，结合的抗原能更有效地被小鼠骨髓来源的树突状细胞（BMDCs）处理并呈递给OVA特异性T细胞。我们还发现，抗HER2/neu IgG3-(IL-2)结合的ECD(HER2)能非常有效地内化，并且内化的ECD(HER2)不会保留在早期内体区室中，而是运输到抗原处理区室。这些结果与我们早期的体内研究一致，表明抗体-(IL-2)和抗体-(GM-CSF)融合蛋白均可用于增强对包括肿瘤相关抗原（TAAs）在内的免疫原性较差的抗原的免疫反应。
