Induction of ICAM-1 expression on the eosinophilic leukemia cell line-3 (EoL-3) by platelet-activating factor and platelet factor 4.

BACKGROUND

Eosinophils are assumed to transmigrate to local tissue under the direction of the eosinophil chemotactic factor present in allergic inflammatory lesions.

OBJECTIVE

We examined whether PAF and PF4, which are related to eosinophil localization, affect the expression of ICAM-1 on the human eosinophilic leukemia cell line (EoL-3).

METHODS

ICAM-1 expression on EoL-3 cells in the presence or absence of PAF or PF4 was assessed by immunofluorescent analysis. The presence of sICAM-1 in culture supernatants of EoL-3 cells was detected with an ELISA kit.

RESULTS

Both PAF and PF4 enhanced the expression of ICAM-1 on EoL-3 cells. We found no difference in sICAM-1 concentration with or without PAF or PF4.

CONCLUSIONS

The eosinophil chemotactic factors PAF and PF4 not only may attract eosinophils, but they may enhance the expression of ICAM-1 on eosinophils at the site of the lesion. Further, it is suggested that the shedding of ICAM-1 has little relation to the induction of ICAM-1 expression in vitro.