Expression of CD28 and CD86 by human eosinophils and role in the secretionof type 1 cytokines (Interleukin 2 and interferon gamma): Inhibition by immunoglobulin A complexes
G. Woerly et al., Expression of CD28 and CD86 by human eosinophils and role in the secretionof type 1 cytokines (Interleukin 2 and interferon gamma): Inhibition by immunoglobulin A complexes, J EXP MED, 190(4), 1999, pp. 487-495
Eosinophils are the source of various immunoregulatory cytokines, but the m
embrane molecules involved in their secretion have not been clearly identif
ied. Here we show that peripheral blood eosinophils from hypereosinophilic
patients could express membrane CD86 but not CD80. The T cell costimulatory
molecule CD28 is also detected on the eosinophil surface. CD28 ligation bu
t not CD86 ligation resulted in interleukin (IL)-2 and interferon (IFN)-gam
ma secretion by eosinophils, whereas IL-4, IL-5, and IL-10 were not detecte
d. In contrast to T cells requiring two signals for effective stimulation,
CD28 ligation alone was sufficient for optimal eosinophil activation. Eosin
ophil-derived IL-2 and IFN-gamma were biologically active, as supernatants
from anti-CD28-treated cells were able to induce CTLL-2 proliferation and m
ajor histocompatibility complex class II expression on the colon carcinoma
cell line Cole 205, respectively. Addition of secretory immunoglobulin (Ig)
A-anti-IgA complexes, which could induce the release of IL-10, very signifi
cantly inhibited both CD28-mediated IL2 and IFN-gamma release. These result
s suggest that the release of type 1 (IFN-gamma and IL-2) versus type 2 cyt
okines by eosinophils is not only differential but also dependent on cross-
regulatory signals. They confirm that through activation of costimulatory m
olecules, eosinophils could function as an immunoregulatory cell involved i
n the release of both type 1 and type 2 cytokines.