In anti-thymocyte/Thy-1 autoreactive μκ transgenic (ATAμκ Tg) Pla2g2a+ BALB/c background C.B17 mice generated NKT2 cells that continuously control CD1d+ B1 B cells through old aging and lost CD1d in B1 B cells generating strong B1 ATA B cell leukemia/lymphoma. This evidence concerns the gene THY1 and lymphoma.