Total body irradiation (TBI) triggers acute injury of sensitive cell populations in the bone marrow and the intestine thus triggering a cascade of delayed damage responses causing massive cell death through diversified programmed mechanisms and penultimately leading to multiple organs failure and lethality. Based on this principle, the radiomitigative strategies should include precisely timed treatments with specific regulators of individual pathways dominating the pathogenic process at this particular stage. Both JP4-039, an anti-apoptotic GS-nitroxide (Rwigema, J.C., et al., Int. J Radiat Oncol Biol Phys, 80(3):860-868, 2011), and Necrostatin-1, an inhibitor of necroptosis (Huang Z., et al., Biochemica at Biophysica Acta, 1862:850-856, 2016), have been shown to be effective irradiation mitigators. We determined whether proteins detectably altered in the plasma, bone marrow, and intestine of total body irradiated mice could be used as signatures to direct sequenced administration of two radiation mitigators with distinct mechanisms of action. C57BL/6NTac adult female mice were irradiated to the LD50/30 dose of 9.25 Gy TBI, and were evaluated daily over 7 days in 4 groups: 1) Radiation Only; 2) 9.25 Gy + JP4-039 at 24 hrs post-irradiation; 3) 9.25 Gy + Necrostatin-1 at 48 hrs post-irradiation; and 4) 9.25 Gy + both JP4-039 at 24 hrs post-irradiation + Necrostatin-1 at a second delayed time point post-irradiation. Luminex immunoassays were run on plasma, intestine, and bone marrow for each group (n=4-5 each data point) at serial time points at day 0 (prior to irradiation), 1, 2, 3, 4, 5, 6, or 7 after TBI. We measured 33 proteins known to be associated with response of tissues to ionizing irradiation. Data was used to generate “heat maps” of all 33 proteins to compare each experimental group with radiation only control. Survival studies were carried out for each radiation mitigator combination to determine the best time point for sequential administration of the second radiation mitigator (n=15 for each group). Administration of JP4-039 at 24 hrs post-irradiation (I.V. 20 mg/kg in 100 μl F14 emulsion) delayed the elevation of plasma IL-6 to Day 3 which correlated with the time of increased bone marrow IL-1α signature for the onset of necroptosis. Increased survival was observed after JP4-039 at 24 hrs and when Necrostatin-1 was delayed until 72 hrs post-irradiation. This increased survival correlated with an increase in levels of plasma proteins including G-CSF, IL-6, KC, and eotaxin, which are indicators of stimulated cell proliferation and chemotaxis. Plasma levels of proteins did not always match changes in the bone marrow or intestine. Sequential administration of JP4-039 at 24 hrs and Necrostatin-1 at 72 hrs post-irradiation increased survival, and correlated with increased levels of plasma inflammatory proteins. Elevations in levels of some plasma proteins may reflect irradiation effects on organs other than bone marrow or intestine.