To examine the capacity of HLA-DR expressing eosinophils to serve as antigen-presenting cells (APC) for presenting antigen tetanus toxoid to autologous T lymphocytes.

Freshly isolated eosinophils were cultured in vitro for 24 hours with granulocyte-macrophage colony factor to induce HLA-DR expression, and then exposed to different concentrations of tetanus toxoid. The capacity of HLA-DR⁺eosinophils to function as APC was evaluated with the response of T cell proliferation induced by eosinophils.

HLA-DR⁺eosinophils stimulated T cell proliferation in the presence of tetanus toxoid in a dose-dependent manner. It was also found that the T cell proliferation response elicited by eosinophils was inhibited by anti-HLA-DR monoclonal antibody.

Human eosinophils can uptake and process antigen and function as HLA-DR-dependent APC in stimulating T lymphocyte response.

Eosinophils; Antigen-presenting cell; Lymphocyte