The invention relates to a method for generating an antibody binding to a cell surface protein of interest, the method comprising the following steps: (a) providing a non-human cell which does not express the endogenous form of the cell surface protein of interest but expresses an exogenous form of the cell surface protein of interest comprising at least one human segment; (b) immunization of a non-human animal with the cell line provided in step (a); (c) generation of hybridomas from the immunized non-human animal of step (b); (d) screening for an antibody that binds to the cell surface protein of interest by contacting the antibodies secreted by the hybridomas of step (c) with human cells which do not express the endogenous form of the cell surface protein of interest but express an exogenous form of the cell surface protein of interest comprising at least one human segment.