Y. Motegi et H. Kita, INTERACTION WITH SECRETORY COMPONENT STIMULATES EFFECTOR FUNCTIONS OFHUMAN EOSINOPHILS BUT NOT OF NEUTROPHILS, The Journal of immunology (1950), 161(8), 1998, pp. 4340-4346
Eosinophils and their products are important in the pathophysiology of
allergic inflammation in mucosal tissues. Secretory component bound t
o IgA mediates transepithelial transport of IgA and confers increased
stability on the resultant secretory IgA; however, the effect of secre
tory component on the biologic activity of IgA is unknown. Here, we re
port that secretory IgG and secretory component preferentially activat
e human eosinophils. When eosinophils were stimulated with immobilized
secretory IgA, degranulation and superoxide production were two- to t
hreefold greater than when stimulated with serum IgA, In contrast, neu
trophils responded similarly to secretory IgA and serum IgA, Flow cyto
metric analysis showed that eosinophils bound to purified secretory co
mponent. The binding of I-125-Iabeled secretory component was inhibite
d by unlabeled secretory component or secretory IgA hut not by serum I
gA, Superoxide production by eosinophils stimulated with cytokines or
IgG was enhanced synergistically by immobilized secretory component; s
ecretory component showed no effect on neutrophil activation. Finally,
anti-CD18 mAb abolished eosinophil superoxide production stimulated w
ith secretory IgA or secretory component but not with serum IgA, sugge
sting a crucial role for beta(2) integrins in eosinophil interactions
with secretory IgA or secretory component. Thus, secretory component p
lays important roles in activating eosinophil functions but not neutro
phil functions. This preferential interaction between secretory compon
ent and eosinophils may provide a novel mechanism to regulate mucosal
tissue inflammation.