DIETARY SUPPLEMENTATION WITH L-ARGININE - MODULATION OF TUMOR-INFILTRATING LYMPHOCYTES IN PATIENTS WITH COLORECTAL-CANCER

Background Dietary supplementation with L-arginine enhances natural cy totoxicity in peripheral blood lymphocytes but its effect on infiltrat ing lymphoreticular cells within a tumour microenvironment is unknown. The effects of dietary supplementation with L-arginine on tumour-infi ltrating lymphocytes (TILs) in patients with colorectal cancer were ev aluated. Methods Eighteen patients received either a standard hospital diet (controls) or a standard diet supplemented with 30 g per day of L-arginine for 3 days before surgery. Tumour biopsies were taken at su rgery and lymphocyte subsets (CD antigens) and macrophages examined im munohistochemically. Results Tumours from patients receiving L-arginin e contained increased numbers of specific cell subsets within the tumo ur which expressed CD16 (P = 0.004) and CD56 (P = 0.001) surface marke rs, when compared with tumours from control patients. There were no di fferences in the total number of T and B cells, T helper and T suppres sor cells. Conclusion Dietary supplementation with L-arginine signific antly alters the spectrum of TILs in human colorectal cancers in vivo. These findings have important implications for new strategies in anti cancer treatment.