Vaccine composition containing IL-15 for active immunization to treatment diseases related to over-expression of this cytokine. The technical aim pursued in this invention is to inhibit IL-15 activity through development of a therapeutic vaccine which elicits IL-15 neutralizing antibodies in the immunized host.IL-15 can be presented in this vaccine composition either alone or coupled to a carrier such as the P64k protein with a vaccine adjuvant such as Aluminum hydroxide.Besides, this invention is related to the use of this vaccine for treatment of Rheumatoid arthritis and other IL-15 over-expressing related diseases, and leukemia, where this cytokine acts as a growth factor.