Immunization with antigen-pulsed dendritic cells significantly improves the immune response to weak self-antigens

A Comprehensive Experimental Guide to Studying Cross-Presentation in Dendritic Cells In Vitro

Cross-presentation was first observed serendipitously in the 1970s. The importance of it was quickly realized and subsequently attracted great attention from immunologists. Since then, our knowledge of the ability of certain antigen presenting cells to internalize, process, and load exogenous antigens onto MHC-I molecules to cross-prime CD8+ T cells has increased significantly. Dendritic cells (DCs) are exceptional cross-presenters, thus making them a great tool to study cross-presentation but the relative rarity of DCs in circulation and in tissues makes it challenging to isolate sufficient numbers of cells to study this process in vitro. In this paper, we describe in detail two methods to culture DCs from bone-marrow progenitors and a method to expand the numbers of DCs present in vivo as a source of endogenous bona-fide cross-presenting DCs. We also describe methods to assess cross-presentation by DCs using the activation of primary CD8+ T cells as a readout. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Isolation of bone marrow progenitor cells Basic Protocol 2: In vitro differentiation of dendritic cells with GM-CSF Support Protocol 1: Preparation of conditioned medium from GM-CSF producing J558L cells Basic Protocol 3: In vitro differentiation of dendritic cells with Flt3L Support Protocol 2: Preparation of Flt3L containing medium from B16-Flt3L cells Basic Protocol 4: Expansion of cDC1s in vivo for use in ex vivo experiments Basic Protocol 5: Characterizing resting and activated dendritic cells Basic Protocol 6: Dendritic cell stimulation, antigenic cargo, and fixation Support Protocol 3: Preparation of model antigen coated microbeads Support Protocol 4: Preparation of apoptotic cells Support Protocol 5: Preparation of recombinant bacteria Basic Protocol 7: Immunocytochemistry immunofluorescence (ICC/IF) Support Protocol 6: Preparation of Alcian blue-coated coverslips Basic Protocol 8: CD8+ T cell activation to assess cross-presentation Support Protocol 7: Isolation and labeling of CD8+ T cells with CFSE.

Behaviour of four different B16 murine melanoma cell sublines: C57BL/6J skin

Transplantable murine melanomas are well-established models for the study of experimental cancer therapies. The aim of this study was to explore the behaviour of four different B16 murine melanoma cell sublines after inoculation into C57BL/6J mice; and, more specifically to analyse skin changes, with respect to two specific parameters: clinical (tumour volume, melanin amount, erythema) and histological (H & E, S100, VEGF expression). Both non-invasive and invasive analysis showed that B164A5 is the most aggressive melanoma cell line for C57BL/6J's skin, followed by B16F10 and then by diminished aggressive growth pattern by the B16GMCSF and B16FLT3 cell lines.

A characterization of four B16 murine melanoma cell sublines molecular fingerprint and proliferation behavior

Background

One of the most popular and versatile model of murine melanoma is by inoculating B16 cells in the syngeneic C57BL6J mouse strain. A characterization of different B16 modified cell sub-lines will be of real practical interest. For this aim, modern analytical tools like surface enhanced Raman spectroscopy/scattering (SERS) and MTT were employed to characterize both chemical composition and proliferation behavior of the selected cells.

Methods

High quality SERS signal was recorded from each of the four types of B16 cell sub-lines: B164A5, B16GMCSF, B16FLT3, B16F10, in order to observe the differences between a parent cell line (B164A5) and other derived B16 cell sub-lines. Cells were incubated with silver nanoparticles of 50–100 nm diameter and the nanoparticles uptake inside the cells cytoplasm was proved by transmission electron microscopy (TEM) investigations. In order to characterize proliferation, growth curves of the four B16 cell lines, using different cell numbers and FCS concentration were obtained employing the MTT proliferation assay. For correlations doubling time were calculated.

Results

SERS bands allowed the identification inside the cells of the main bio-molecular components such as: proteins, nucleic acids, and lipids. An "on and off" SERS effect was constantly present, which may be explained in terms of the employed laser power, as well as the possible different orientations of the adsorbed species in the cells in respect to the Ag nanoparticles. MTT results showed that among the four tested cell sub-lines B16 F10 is the most proliferative and B164A5 has the lower growth capacity. Regarding B16FLT3 cells and B16GMCSF cells, they present proliferation ability in between with slight slower potency for B16GMCSF cells.

Conclusion

Molecular fingerprint and proliferation behavior of four B16 melanoma cell sub-lines were elucidated by associating SERS investigations with MTT proliferation assay.