Agents which damage or differentiate myeloid or lymphoid cells, e.g., HTLVIII, A-23187, linoleic or arachidonic acids, organic solvents or cell crowding concurrently switch lipid metabolism away from structural phospholipid and diacyl glycerol synthesis toward triglyceride synthesis. These effects are associated with an increase in permeability of Ca(++). These cellular change-, including the cessation of growth can all be abrogated by oxo elaidic acids or by oleic acid. The oxo fatty acids also specifically inhibit triglyceride synthesis. Thus, these data suggest that the ratio of various fatty acid concentrations presented to growing inflammatory cells is a major factor controlling their growth, differentiation and survival.