Resemblance with human AITL disease increased upon immune-phenotyping showing that the tumor mouse tissues (spleen, liver, lymph nodes) were marked by a specific increase of CD4+PD1+CXCR5+ICOS+CXCL-13+Bcl-6+ T follicular helper (Tfh) cells as compared to WT. This evidence concerns the gene ICOS and neoplasm.