75Se-Release: A Short and Long Term Assay System for Cellular Cytotoxicity

摘要: Abstract The γ-emitting aminoacid 75 Se-selenomethionine ( SeM) was examined as a target cell label in cytotoxic assays. It efficiently taken up by activated, intensely metabolizing cells of various types but hardly at all resting or low-metabolizing cells. Culturing activated methionine-deficient medium with 3–5 μCi SeM/ml for 18–22 h usually resulted an uptake 3–20 cpm/cell which 3–200 times that 51 Cr marked SeM-labelled kept ambient temperature 37°C, maintained high radioactivity per and viability above 85% least 72 without significant increase spontaneous isotope release loss sensitivity subsequent tests. Se-labelled material released from not reutilized unlabelled lymphoid Provided the were carefully washed after labelling optimal culture conditions, reasonably low baseline (usually 0.6–1.8% input/h) control allowed performance long-term assays to 54 h. However, strong reactions (e.g. ADCC) could cause over 50% specific Se-release within 5 With constant amounts effector (3.6 × 10 3 /well) identical even higher, releases obtained on 6 2 targets compared 1 4 targets/well. Thus, assay offers single monitoring system suitable short (3–6 h) long term 44 microscale, using less Its permits evaluation weak well early delayed onset cytotoxicity. In addition, γ-spectrometer Se can easily be distinguished Cr. Due this, improved method (10 Cr/ml h), double γ-labelling cellular proteins is available provides new possibilities interactions