Retrospective Analyses of Serum Lipids and Lipoproteins and Severity of Disease in ⁶⁰Co-irradiated Sus scrofa domestica and Macaca mulatta

Profound neutropenia that provides an opportunity for infections to develop into sepsis remains an important cause of morbidity and mortality in patients after irradiation. Human clinical studies find extremely low concentrations of cholesterol (less than 120 mg/dl) associated with high risk of death in critically ill adult patients admitted to intensive care units. This retrospective study was initiated as part of separate investigations of radiation-induced acquired infections in 2 large animal species receiving high-dose whole-body irradiation from a ⁶⁰Co -photon source. Nine Yucatan minipigs (Sus scrofa domestica) and 16 rhesus macaques (Macaca mulatta) were evaluated for sepsis, serum lipid and lipoprotein concentrations, and other blood parameters. For each species, animals were grouped into 2 categories—septic and nonseptic—and severity of disease was quantified by use of a scoring system. Significantly lower high-density lipoprotein (HDL) concentrations were found in the septic pigs at 24 and 48 h as compared with nonseptic pigs. HDL was significantly decreased in septic macaques within 24 h and 3 to 4, 6 to 7, and 9 to 10 d after diagnosis of sepsis, compared with that in nonseptic macaques. Coupled with hypocholesterolemia, decreased serum HDL was the parameter that was associated with disease severity at the time of sampling. Our data indicate that HDL is a reliable marker for severity of disease in these 2 preclinical models of irradiation-induced sepsis.