The invention provides an oligonucleotide with a sequence of SEQ ID NO: 1 or its functional homolgue, a composition comprising the same and a method for treating B cell neoplasm by using the oligonucleotide or its functional homologue or the composition comprising the oligonucleotide. The oligonulceotide induces the apoptosis of B cell neoplastic cells, up-regulates CD40 on B cell neoplastic cells and stimulates the production of IL-10 from B cell neoplastic cells.
