**4. Materials and Methods**

#### *4.1. Animal Studies and Ricin Intoxication*

Ricin preparation and animal experiments were performed at the Israel Institute for Biological Research as described previously [41]. All animal experiments were performed in accordance with Israeli regulations and were approved by the Ethics Committee for Animal Experiments at the Israel Institute for Biological Research (protocol identification code M-18-2016, date of approval: 8 September 2016). Treatment of animals was in accordance with regulations outlined in the USDA Animal Welfare Act and the conditions specified in the Guide for Care and Use of Laboratory Animals (National Institute of Health, 1996). Lung and blood samples were collected from ricin-intoxicated mice at 24 h after intranasal exposure to 7 μg/kg of crude ricin. Whole blood (0.5 mL/mouse) was extracted and treated with RBC lysis bu ffer (Sigma-Aldrich, St. Louis, MO, USA) followed by centrifugation of 1200 × g for 20 min to isolate PBMCs. Lungs and PBMCs were stored at −80 ◦C.
