Allergy contact dermatitis is a type IV delayed type hypersensitivity that is induced by exogenous compounds and involves many cell types. Traditional animal testing uses guinea pigs or mice as a model. With progress of the adverse outcome pathway (AOP) on skin sensitization, a concept for development of alternative methods based on a molecular initiating event and key events is provided. Dendritic cell (DC) activation plays a key role in the AOP. Many alternative methods have been developed, with several methods validated and accepted as guidance for assays. This paper examines DC screening, characteristics of test parameters, and limitations and applicability of DC-derived methods. Progress on interactions between DCs and other cells, co?culture systems, and the human body-on-a-chip will also be introduced. Altogether, this paper will provide information for optimization of in vitro alternative methods for sensitization detection.