EFFECT OF ESSENTIAL FATTY-ACIDS ON CIRCULATING T-CELL SUBSETS IN PATIENTS WITH COLORECTAL-CANCER

The effect of essential fatty acids (EFA), given orally as dietary sup plements, on the responsiveness in vitro of peripheral blood lymphocyt es (PBL), to the mitogen concanavalin A have been studied in 10 patien ts with localized and 14 patients with advanced colorectal cancer. The degree of lymphocyte activation was assessed by measuring the amount of tritiated [H-3]thymidine incorporated into newly synthesised lympho cyte DNA. The results were expressed as stimulation indices. T cell re sponses to concanavalin A stimulation showed a significant reduction o f stimulation indices following EFA supplementation, in both the local ized (P = 0.026) and advanced (P = 0.016) tumour groups, when compared with pretreatment activity in vitro. Mixing experiments, using EFA-su pplemented and non-EFA-supplemented lymphocytes with concanavalin A, s uggest no enhancement of T suppressor cell activity. Cell surface mark er analysis (fluorescence-activated cell sorting for CD phenotyping) r evealed a reduction of absolute numbers of CD4(+) and CD8(+) lymphocyt es following EFA supplementation. The stimulation indices returned to presupplementation values 3 months following cessation of EFA intake. There was no significant change of these indices in the control (no EF A supplementation) advanced tumour group tested. This study suggests t hat EFA supplementation in patients with colorectal cancer selectively reduces circulating PBL, and T cell subset (including suppresser cell s) numbers and/or activity. Such effects may have an important outcome in patients with malignant disease.