DIETARY SUPPLEMENTATION WITH VERY LONG-CHAIN N-3 FATTY-ACIDS IN MAN DECREASES EXPRESSION OF THE INTERLEUKIN-2 RECEPTOR (CD25) ON MITOGEN-STIMULATED LYMPHOCYTES FROM PATIENTS WITH INFLAMMATORY SKIN DISEASES

T-cell activation and cytokine production play an important role in se veral chronic inflammatory diseases. Because n-3 fatty acids exert ben eficial effects on the clinical state of some of these diseases, we ex amined the effect of dietary supplementation of n-3 fatty acids on T-c ell proliferation, expression of CD25 (interleukin-2 receptor alpha-ch ain), secretion of interleukin-2, interleukin-6 and tumour necrosis fa ctor from T-cells from patients with psoriasis and atopic dermatitis. During 4 months, 21 patients supplied 6 g of highly concentrated ethyl esters of EPA and DHA in gelatin capsules daily to their diet. In the control group 20 patients supplied 6 g per day of corn oil in gelatin capsules to their diet.Eicosapentaenoic acid (20:5, n-3) of serum pho spholipids increased from 14 (min 4-max 42) to 81 (min 59-max 144) mg l(-1) (P < 0.01) in patients with atopic dermatitis receiving n-3 fatt y acids, and from 25 (min 7-max 66) to 74 (min 46-max 142) mg l(-1) (P < 0.01) in patients with psoriasis, whereas docosahexaenoic acid (22: 6, n-3) increased from 65 (min 46-max 120) to 92 (min 54-max 121) mg l (-1) (P < 0.05) and from 81 (min 38-max 122) to 92 (min 63-max 169) mg l(-1) (NS) in atopic and psoriatic patients, respectively. The change s in the serum phospholipid fatty acid profile in the groups receiving n-3 fatty acids, correlate to the dietary intake of corresponding fat ty acids. There was no significant change in the fatty acid pattern of serum phospholipids in the corn oil group before and after supplement ation. Mitogen-induced secretion of interleukin-6 was significantly hi gher in patients with psoriasis compared to patients with atopic derma titis, whereas the secretion of interleukin-2, tumour necrosis factor, PHA-induced T-cell proliferation and expression of CD25 on lymphocyte s were similar in the two groups of patients. Patients receiving suppl ementation of n-3 fatty acids decreased significantly the percentage o f CD25 positive lymphocytes from 40.5 before start to 35.5 (P < 0.05) after the trial. The patients who received corn oil increased the leve l of tumour necrosis factor from 10.95 pg ml(-1) before start to 1536 pg ml(-1) after the trial (P < 0.05). In conclusion, dietary intake of very long-chain n-3 fatty acids may suppress the expression of CD25 p ositive lymphocytes, which may partly account for the anti-inflammator y effect exerted by these fatty acids.