L- Arginine has great potential as animmunomodulator and may prove useful in catabolic conditions such as severesepsis and postoperative stress. There is a body of evidence suggesting thatsupplemental arginine upregulates immune function and reduces the incidence ofpostoperative infection. More modest improvements in nitrogen balance have beenobserved. Tumor response to arginine appears to depend on the immunogenicity ofthe particular tumor and on the requirement of arginine by the tumor as agrowth substrate. Of note, ornithine shares the thymotrophic, immunostimulatoryand secretagogue effects of arginine. It is, therefore, likely that thesecompounds share the same cellular mechanism of action or that arginine acts viaincreasing the concentration of available ornithine- Nutrition. 1998 Jul-Aug;14(7-8):611-7.