The present invention relates to an irradiated mouse comprising a human immune model system, wherein said irradiated mouse comprises a) radiation-resistant follicular dendritic cells (FDCs) b) a population of human PBL,s and, c) antigen/antibody immune complexes, wherein said mouse is immunocompetent before irradiation. The invention also relates to methods of producing the irradiated mouse and methods which utilise the irradiated mouse.