Antigen cross-presentation is a functional feature of some specialized antigen-presenting cells, allowing them to internalize and process antigens from extracellular sources and present them via major histocompatibility class I (MHC-I) molecules to CD8+ T lymphocytes. This process is critical for the mounting of protective immunity to tumors and intracellular pathogens. Antigen cross-presentation can be monitored through in vivo and in vitro assays that are key to evaluate the efficiency and the molecular and cellular mechanisms of cross-presentation by a given cell type. This chapter intends to complement published protocols by describing how to use MutuDC, a murine immortalized type 1 conventional dendritic cell-like line, and a “nonprofessional” human antigen-presenting cell, the human embryonic kidney HEK 293T cell line, endowed with the ability to cross-present immune complexes through overexpression of an Fc receptor, for in vitro antigen cross-presentation assays.