The invention relates to a cell line expressing the gamma chain of the FcεRI receptor and human CD303 antigen, characterized in that said cell line is transfected in a stable manner by an expression vector comprising a nucleic acid molecule coding for human CD303 antigen and having strong expression of human CD303 on the surface thereof, e.g. at least 10000 molecules of human CD303 per cell, as well as a vector or vector kit that can be used to co-express the gamma chain of the FcεRI receptor and human CD303 antigen, and different uses of the cell line of the invention.