The present invention relates to a composition for human and animal use as a therapy for the treatment of tumors acquired immunodeficiency syndrome and leukemias. The composition of the present invention for human and animal use as antitumor agent consists of a mixture comprising or preferably consisting of a strain of bacteria Lactobacillus reuteri LRE 03 DSM 23879 which is able to strongly stimulate the production of pro inflammatory cytokines (Th1) interferon INF gamma said cytokines exhibit a marked antitumor activity and/or a strain of bacteria Lactobacillus salivarius LS06 DSM 26037 which is able to strongly stimulate the production of dendritic cells said dendritic cells also exhibit a marked antitumor activity.
