Supernatants from activated eosinophils promote elongation of neurites in PC-12 cells.

Eosinophils were suspended in RPMI 1640 medium supplemented with 10% DCS and incubated with medium alone or sIgA (20 μg/mL) and antihuman sIgA monoclonal antibody (1:10 000) plus 25 ng/mL IL-5 for 24 hours at 37°C. After culture, cell-free supernatants were collected. PC-12 cells were incubated with medium alone (A), 2 ng/mL NGF (B), supernatant of eosinophils cultured with medium alone (C), or supernatant of eosinophils cultured with sIgA immune complex and IL-5 (D) for 24 hours. The cell morphology was examined under the inverted microscope. Bar = 50 μm. Original magnification × 100.