High arginine levels in intravenous hyperalimentation abrogate post-traumatic immune suppression

Abstract

Trauma victims often suffer immune system failure. Oral arginine has strong immune-enhancing properties. The metabolic, hormonal, and immune effects of increasing concentrations of arginine as part of post-trauma intravenous hyperalimentation (IVH) were studied. Groups of 11-14 rats, 275-350 g, underwent jugular vein catheterization and bilateral closed femoral fractures under anesthesia. IVH was started immediately postinjury at a rate of 0.8-1 ml/100 g body wt/hr and continued for 5 days. Twenty percent dextrose and three different amino acid mixtures were given as follows: (A) FreII (1.55 g ARG/1); (B) FreIII (4.05 g ARG/1); (C) modified FreIII (7.9 g ARG/1). All rats lost weight over the 5-day postinjury period; however, rats in groups B and C lost significantly less weight than rats in group A (-3.4 +/- 0.8% of initial body weight and -3.6 +/- 0.9% vs -6.1 +/- 1.2%, P less than 0.05). Rats in group A had negative cumulative nitrogen balance, while those in groups B and C were in highly positive balance. No significant difference in body weight change or nitrogen balance was noted between groups B and C. Trauma-induced thymic involution as assessed by thymic weight and lymphocyte content was greatest in group A, which received the lowest amount of arginine, and was linearly abrogated by increasing the amount of arginine administered (A less than B less than C). Thymocyte immune responsiveness increased with the amount of arginine given as assessed by mitogenesis in response to Con A (stimulation index: A--151.3 +/- 28.8 vs B--243.6 +/- 29.2, P less than 0.01 vs C--321.8 +/- 22.3, P less than 0.001 vs A and P less than 0.02 vs B) and PHA (A--65.0 +/- 14.3 vs B--67.7 +/- 15.3, NS, vs C--117 +/- 14.0, P less than 0.005 vs A and B).(ABSTRACT TRUNCATED AT 250 WORDS)