Interleukin-15 and the growth of tumor derived activated T-cells.

Interleukin-15 was tested to determine whether this recently discovered cytokine was capable of stimulating the growth of tumor derived activated T cells in culture (TDAC, also referred to as tumor infiltrating lymphocytes). When established cultures of IL-2 induced, IL-2 dependent TDAC were tested, IL-15 stimulated growth in a dose dependent manner, alone or in the presence of IL-2. One established TDAC was cultured with IL-15 alone for 18 passages over a 10 week period. Comparing IL-2 and IL-15 treated cultures, growth rate with IL-15 was slower. IL-15 doubled the secreted interferon alpha and granulocyte-macrophage colony stimulating factor. IL-15 and IL-2 were compared in primary TDAC cultures. IL-15 induced TDAC outgrowth in 3 of 6 cultures. IL-2 induced outgrowth in all 6. Tumor cells were eliminated as TDAC grew out in both IL-2 and IL-15 treated cultures. These results suggested that IL-15 like IL-2, is capable of stimulating the growth of TDAC with antitumor activity, but with certain distinct effects which may be of interest therapeutically.