Abstract: An improved in vitro cell culture process for producing in high yield and purity a serum-free and mitogen-free interleukin-2-containing conditioned supernatant. The incubation steps during stimulation and conditioning of the interleukin-2 producing cells is carried out with a rapidly rotating roller bottle culture system. Yields of interleukin-2 are on the order of 10-fold and higher than obtained by similar cultivations carried out in flat dishes or tubes or in a roller bottle culture system rotated at conventional speeds. Improvement in yields in both the static and roller culture systems are also achieved by incubating the IL-2 producing cells under high oxygen concentrations, for example atmospheres of at least 70% O.sub.2 and at least 5% CO.sub.2. In addition to using peripheral mononuclear blood cells (PBL) as the source of leukocytes containing the IL-2 producer cells, it is also possible to use buffy coat cells which are readily available as a waste by-product from blood banks.

Abstract: A serum-free and mitogen-free T-cell growth factor (interleukin-2) preparation is prepared from human, bovine, or procine peripheral mononuclear blood cells which are washed several times with a liquid tissue culture medium and then stimulated in a tissue culture medium supplemented with serum and mitogen. The separated stimulated cells are again washed with fresh tissue culture medium to remove substantially all of the serum and mitogen. The washed cells are suspended in fresh tissue culture medium and conditioned under incubation conditions to transfer the growth factor into the liquid. The tissue culture medium separated from the stimulated cells can be recycled to stimulate additional cells. The supernatant can be concentrated from 50 to 100-fold on an ultrafilter. The supernatant can activate the production of natural killer cells in patients suffering from tumors.