Human blood eosinophils express Notch ligands J1 and J2 protein. (A) Freshly isolated blood eosinophils or CD4⁺ T cells (positive control) were lysed and immunoprecipitated with anti-J1 or isotype control Abs. Immunoprecipitated proteins were immunoblotted with anti-J1 Abs. n = 3. Saponin-permeabilized eosinophils were analyzed by flow cytometry for expression of J1 (B) or J2 (C). Shaded histograms = isotype control. (D) Freshly isolated eosinophils were processed for immuno-EM and stained with Abs against J1. J1 expression was observed at the plasma membrane (Di) and within eosinophil-specific granules (Dii). Bars represent 1.1 μm (D) and 650 nm (Di,ii).