assessment of roles for calreticulin in the cross-presentation of soluble and bead-associated antigens评估的角色calreticulin cross-presentation的可溶性和bead-associated抗原.pdf

Assessment of Roles for Calreticulin in the Cross- Presentation of Soluble and Bead-Associated Antigens 1,2 3 3 1,2 Natasha Del Cid , Lianjun Shen , Janice BelleIsle , Malini Raghavan * 1 Graduate Program in Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 2 Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 3 Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America Abstract Antigen cross-presentation involves the uptake and processing of exogenously derived antigens and their assembly with major histocompatibility complex (MHC) class I molecules. Antigen presenting cells (APC) load peptides derived from the exogenous antigens onto MHC class I molecules for presentation to CD8 T cells. Calreticulin has been suggested to mediate and enhance antigen cross-presentation of soluble and cell-derived antigens. In this study, we examined roles for calreticulin in cross-presentation of ovalbumin using a number of models. Our findings indicate that calreticulin does not enhance in vitro cross-presentation of an ovalbumin-derived peptide, or of fused or bead-associated ovalbumin. Additionally, in vivo, calreticulin fusion or co-conjugation does not enhance the efficiency of CD8 T cell activation by soluble or bead-associated ovalbumin either in wild type mice or in mice lacking Toll-like receptor 4 (TLR4). Furthermore, we detect no significant differences in cross-presentation efficiencies of glycosylated vs. non-glycosylated forms of ovalbumin.