THE EFFECT OF HUMAN EOSINOPHILS ON CULTURED HUMAN NASAL EPITHELIAL-CELL ACTIVITY AND THE INFLUENCE OF NEDOCROMIL SODIUM INVITRO

Although there is increasing evidence of a pathogenic role for eosinophils in the airway epithelium, there is little direct evidence which demonstrates that eosinophils influence epithelial cell activity in humans. We have cultured human nasal epithelial cells in vitro and studied the effect of isolated human eosinophils on the ciliary beat frequency (CBF) and cell membrane integrity of these cells after incubation in the absence or presence of 0.1 muM phorbol 12-myristate 13-acetate (PMA) or 0.1 mg/ml opsonized latex beads and the absence or presence of 10(-5) M nedocromil sodium. CBF was monitored by an analogue contrast-enhancement technique, and cell damage was assessed by release of Cr-51 from the cells. Cell cultures were also assessed for the percentage of eosinophil cationic protein (ECP) released into the medium at the end of incubation. Neither 0.1 muM PMA, 0.1 mg/ml opsonized latex beads, 10(-5) M nedocromil sodium, nor eosinophils alone altered the CBF of the epithelial cells. PMA-stimulated eosinophils, however, attenuated the CBF significantly, from 10.2 +/- 0.3 to 8.8 +/- 0.4 Hz (P < 0.05) after 15 h of incubation. Similarly, opsonized latex bead-stimulated eosinophils led to a significant attenuation of CBF from 9.2 +/- 0.3 to 8.4 +/- 0.3 Hz (P < 0.05), 6.9 +/- 0.5 Hz (P < 0.001), and 7.5 +/- 0.3 Hz (P < 0.001) after 2, 15, and 24 h of incubation, respectively. Of the two activating agents, only opsonized latex beads induced release of significantly greater amounts of ECP from eosinophils (30.4 +/- 5.5% of total, compared with control values of 13.1 +/- 2.6% of total; P < 0.05). Nedocromil sodium (10(-5) M) abrogated both the PMA- and latex bead-stimulated eosinophil-induced attenuation of CBF and also blocked the release of ECP from the eosinophils. Studies of cell damage demonstrated that incubation of epithelial cells in the presence of eosinophils and PMA or opsonized latex beads led to significantly greater release of Cr-51 (32.7 +/- 5.7 % and 31.5 +/- 3.8 %, respectively; P < 0.05) compared with incubation of the cells in the presence of eosinophils alone (14.4 +/- 1.3 %). These data suggest that "activated" eosinophils are capable of directly causing airway epithelial cell dysfunction and may be inhibited by agents such as nedocromil sodium.