Effect of spleen-cell-conditioned medium on [H-3]-choline uptake by retinal cells in vitro is mediated by IL-2

Cytokines are essential molecules throughout the development of the nervous system and also play an important role during the adult life span. In the present work, we analyzed in vitro the effect of spleen-cell-conditioned me dium (SCM) on the survival and [H-3]-choline uptake of neonatal rat retinal cells. SCM induced an increase in neuronal survival, glial cell proliferat ion and neurite outgrowth, as evaluated by biochemical and morphological cr iteria. These effects were time dependent; after 120 h, SCM induced a 6-fol d increase in the total protein level. The effect of SCM was blocked both b y the inhibition of protein tyrosine kinase activity (10 mu M genistein) an d by the inhibition of cell division (20 mu M fluorodeoxyuridine). SCM also increased the uptake of [H-3]-choline by retinal cells. The effect was tim e dependent. The maximum effect was obtained after 48 h and was maintained at a high level until 120 h. Treatment by 10 mu M genistein and 15 mu M bis (2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM) (an intracellu lar calcium chelator) completely blocked this effect. However, 20 mu M fluo rodeoxyuridine did not abolish it. Conditioned medium obtained from glial c ells stimulated with SCM (S-GCM) induced an effect on [H-3]-choline uptake earlier than that promoted by SCM. Anti-interleukin-2 (IL-2) antibodies blo cked the effect of both SCM and S-GCM on [H-3]-choline uptake after 48 and 72 h. IL-2 (50 U/ml) elicited the same effect as that observed when the cel ls were maintained in the presence of SCM. Taken together, our results sugg est that IL-2 plays an important role in controlling the survival and diffe rentiation of retinal cells in vitro. Copyright (C) 2000 S. Karger AG. Base l.