Conditioned media from activated lymphocytes maintain sympathetic neurons in culture.

Nerve growth factor (NGF) is vital for the development and maintenance of sympathetic neurons. In the present report, we demonstrate that NGF maintenance activity can be substituted by lymphoid cells. Indeed, coculturing lymphoid cells with sympathetic neurons in the absence of exogenous NGF resulted in neuronal survival, as measured by morphological and biochemical criteria. In addition, conditioned media from concanavalin A-activated lymphoid cells could replace NGF. The lymphoid secreted factor differs from NGF in its inability to induce neuronal differentiation, and in its lack of cross-reactivity with NGF in radioimmunoassays. We thus discovered a potential novel source for a factor essential for neuronal survival.