The anti-inflammatory properties of IL-4, IL-10, IL-13 and TGF-beta ar
e associated with their ability to repress the production of pro-infla
mmatory cytokines and to favour the release of interleukin-1 receptor
antagonist (IL-1ra). Here, we investigate their actions on activated h
uman polymorphonuclear cells (PMN), IL-4 and TGF-beta were able to inc
rease the production of IL-1ra, however only IL-4 were able to further
increase IL-1ra production in the presence of LPS. When IL-1ra produc
tion by PMN was induced by tumour necrosis factor-alpha (TNF-alpha), I
L-10 and IL-4 both amplified its release and its presence as a cell-as
sociated form, In conclusion, IL-10 which was unable to induce IL-1ra
by itself or to amplify the LPS-induced production by PMN, was able to
increase its release when TNF-alpha, is the triggering signal, IL-4 w
as active in the different combinations tested; IL-13 and TGF-beta did
not further modulate LPS- and TNF-alpha-induced IL-1ra production by
PMN. (C) 1996 Academic Press Limited