We have previously shown that lymphocytes from idiopathic minimal-lesi
on nephrotic patients produce a lymphokine (supernatant factor) that i
ncreases the (35)sulfate uptake in the glomerular basement membrane (G
EM), The purpose of this report was to further characterize the supern
atant factor by studying the effects of interleukins (IL) 2-4, 6, and
8, granulocyte-macrophage colony stimulating factor, and tumor necrosi
s factor on the (35)sulfate incorporation by rat glomeruli in vitro. A
significant increase in GEM (35)sulfate uptake was only seen when the
glomeruli were cultured with the addition of IL-8 as compared with co
ntrol cultures: 10.8 +/- (SEM) 1.7 and 7.9 +/- 1.4 cpm/mu g GEM protei
n, respectively (p < 0.005), IL-8 reproduces the effect of the reporte
d supernatant factor on the GEM (35)sulfate uptake. Because IL-8 was d
etected in the supernatant of peripheral mononuclear cell cultures fro
m idiopathic minimal-lesion nephrotic syndrome patients in relapse and
because the increased GEM (35)sulfate incorporation induced by the su
pernatant factor has been abolished by the addition to the culture med
ia of anti-IL-8 neutralizing antibodies, we postulate that IL-8 is the
previously described supernatant factor.