Since transfer of PBMC often causes lethal GvHD, the naïve CD4+ T cell fraction was removed from PBMCs, and RA patient-derived CD4+ memory T cells and B cells were transferred sequentially, resulting in sustained production of IgM rheumatoid factor autoantibodies in human cell-engrafted NOG mice (233). The gene discussed is CD4; the disease is graft versus host disease.