The long range goal of the proposed research is to develop serum- free media formulations for the culture of human leukocytes in vitro. The objective of Phase I studies is to develop serum-free medium that would allow maximum growth and cytotoxic activity of non-mitogen activated human lymphokine activated killer cells, natural killer cells, monocytes and mitogen activated cytotoxic T cells. Based on Phase I results, Phase II studies will concentrate on producing serum-free medium for the batch production of cancer patient-derived leukocytes for medical research. This medium would alleviate many of the problems associated with cell propagation in the presence of animal sera or pooled human sera. This Phase I proposal outlines the development of a high quality serum-free medium utilizing biological components derived solely from human sources. The composition and optimal concentrations of each component of the medium will be selected with particular concern for the growth and maintenance of human cells. By controlling the external signals the role various biological response modifiers play on cytotoxic activity can be clearly evaluated.