The present invention relates to a composition for expanding lymphocytes comprising at least two types of cytokines selected from interleukin 2 (IL 2) interleukin 15 (IL 15) and interleukin 21 (IL 21). It further relates to a Method of preparing a population of clinically relevant lymphocytes comprising the steps of: obtaining a body sample from a mammal in particular a tissue sample or body liquid sample comprising at least one lymphocyte and optionally separating the cells in the body sample culturing the body sample in vitroto expand and/or stimulate lymphocytes in the sample wherein the culturing comprises using IL 2 IL 15 and/or IL 21 and optionally determining the presence of clinically relevant lymphocyte in the cultured sample.The present invention also relates to an immunotherapy and the population of clinically relevant lymphocytes.
