Within CD4 and CD8 subsets, we identified overlapping Vβ families in the responses against myeloma cells (anti-tumor) and Balb/cJ cells (alloreactive), underlining the relationship between anti-tumor responses and GvHD, whereas some Vβ families within CD4 T cells specifically respond to either myeloma or host alloantigens. Here, CD8A is linked to plasma cell myeloma.