[Impact of CPP-Id on expression of co-stimulating molecules on dendritic cells in mice]

Idiotypic immunoglobin (Id) derived from B-cell lymphoma, as a tumor-specific antigen, can suppress tumor development by inducing immune response. This study was to confirm the presence of Id epitope on cytotoxic T lymphocytes (Id-CTL) in mouse lymphoma cell line A20, detect the quantity and distribution of cell-penetrating peptide-loaded Id (CPP-Id) in dendritic cells (DCs) at different time points, and explore its impact on the expression of surface molecules on DCs.

Id-CTL epitope in A20 cells was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sequenced. The quantity of CPP-Id and Id alone in DCs and the expression of DC surface molecules were detected by flow cytometry. The process of CPP-Id entering DCs was observed under confocal microscope, and its distribution was observed under fluorescent microscope.

A 660 bp-length fragment was amplified from A20 cells by RT-PCR, and identified as Id-CTL epitope by sequencing. CPP-Id entered DCs quickly during the initial 200 s, but few Id entered DCs. The mean fluorescent intensity (MFI) in DCs was significantly higher in CPP-Id group than in Id group (4.35+/-0.48 vs. 1.14+/-0.33, P<0.005). The expression of surface molecules CD80, CD86, CD54 and MHC-I, MHC-II were higher on the DCs loaded by either CPP-Id or Id alone than on immature DCs.

CPP can enhance the quantity of Id entering DCs. CPP-Id can up-regulate the expression of MHC I, MHC-II and CD80, CD86, and CD54 on DCs, and may help to activate CTLs.