[A study on antigen presentation of eosinophils in vivo and in vitro]

To elucidate the process and characteristics of antigen presentation of eosinophils in vitro and in vivo.

BALB/c mice were sensitized and challenged by ovalbumin to recruit the aggregated eosinophil in the airways. The isolated airway eosinophils were co-cultured with sensitized T lymphocytes. Meanwhile, purified eosinophils were instilled into the trachea of sensitized mice, and then T cells from the draining lymph nodes were collected. The proliferation responses of T cells both in vitro and in vivo were observed.

In the absence of eosinophils in in vitro experiments, T cells did not proliferate even when incubated with exogenous antigen. The addition of ovalbumin sensitized eosinophils (in vivo) yielded significant eosinophil dose-dependent increases in T-cell proliferation. In sensitized mice that received airway instillation of antigen-exposed eosinophils, T-cell proliferation in the paratracheal lymph nodes developed within 1 day, reaching peak at day 3, and declined over 1 week. The in vivo T-cell proliferative responses increased with increasing numbers of eosinophils instilled into the tracheas. In both in vitro and in vivo experiments, antigen-exposed could only present antigen to T cells sensitized with the same antigen.

Eosinophils can uptake and process antigen both in vitro and in vivo, and then present processed antigen to sensitized T cells and thus induce T-cell proliferation. Moreover, eosinophil-induced T-cell proliferation is antigen specific.