COOPERATION BETWEEN FC-GAMMA RECEPTOR-II AND COMPLEMENT RECEPTOR-TYPE-3 DURING ACTIVATION OF PLATELET-ACTIVATING-FACTOR RELEASE BY CYTOKINE-PRIMED HUMAN EOSINOPHILS
T. Vanderbruggen et al., COOPERATION BETWEEN FC-GAMMA RECEPTOR-II AND COMPLEMENT RECEPTOR-TYPE-3 DURING ACTIVATION OF PLATELET-ACTIVATING-FACTOR RELEASE BY CYTOKINE-PRIMED HUMAN EOSINOPHILS, The Journal of immunology, 153(6), 1994, pp. 2729-2735
After priming with cytokines, such as granulocyte-macrophage colony-st
imulating factor (CM-CSF), IL-3, or IL-5, eosinophils are stimulated p
otently by opsonized particles like serum-treated zymosan (STZ), resul
ting in activation of the respiratory burst and production of lipid me
diators, such as platelet-activating factor (PAF) and leukotriene C-4
(LTC(4)). In the present study, the role of the opsonin receptors Fc g
amma RII and CR3 during both STZ-induced activation of the respiratory
burst and PAF release by human eosinophils was investigated. Inhibiti
on studies with blocking mAbs (alpha hFc gamma RII: AT10, IV.3; alpha
CR3: B2.12, 44a) showed that both Fc gamma RII and CR3 are important f
or STZ-induced PAF release by cytokine-primed eosinophils. In contrast
, CR3 is involved in activation of the respiratory burst, whereas Fc g
amma RII seems not to be important, because blocking anti-Fc gamma RII
mAbs had no effect. Subsequently, experiments were performed with zym
osan particles coated with IgG, iC3b, or a combination of both. IgG-co
ated particles poorly activated both responses in GM-CSF primed and un
primed cells. iC3b-Zymosan activated the respiratory burst as well as
zymosan expressing both opsonins (IgC/iC3b-zymosan). In contrast, iC3b
-zymosan induced significantly less PAF release by CM-CSF-primed eosin
ophils than did IgC/iC3b-zymosan, suggesting synergism between Fc gamm
a RII and CR3. This synergistic effect was not observed when Igc-zymos
an and iC3b-zymosan were added simultaneously. Therefore, these data i
ndicate that on human eosinophils, Fc gamma RII and CR3 act synergisti
cally to activate PAF release, provided that their ligands ape in clos
e proximity.