IMMUNOSUPPRESSION BY N-3 FATTY-ACIDS COMPARISON OF GLYCEROL VS ETHYL-ESTERS

Intravenous fish oil prolongs graft survival in a heterotopic cardiac transplant model (PVG rats (RT 1(c)) x Wistar/Kyoto rats (RT 1(1))). T his study elaborates the impact of the ester group on the immunosuppre ssive potential of n-3 fatty acids. Twenty per cent fish oil emulsions (glycerol esters, ethyl esters or concentrated ethyl esters; 9g fat/k g body weight/d) were given by continuous intravenous infusion after t ransplantation until complete rejection. Fish oil glycerol esters prol onged the heart graft survival time to 12.5 vs. 9.5 d (control group i nfused with a corresponding amount of soybean oil) (p<0.005, Mantel-Ha enszel chi-square test). No prolongation of graft survival was achieve d by infusing fish oil ethyl esters or concentrated ethyl esters (9.0 or 9.1 d, respectively). In the fish oil glycerol ester group all subp opulations of graft infiltrating cells were up to 50 percent lower tha n in the control group, while there was no significant difference in t he two ethyl ester groups. PBMC Interleukin(IL)-6 release was signific antly reduced in the fish oil glycerol ester group (22.1+/-4.2 pg/10(6 )PBMC) compared to the controls (73+/-2.6 pg/10(6) PBMC, p<0.0001, Stu dent's t-test), but not in the ethyl ester groups (98.2+/-5.0 pg/10(6) PBMC and 88.0+/-6.2 pg/10(6)PBMC, resp.). Our data demonstrate that pa renteral n-3 fatty acids prolong acute rejection and inhibit PBMC IL-6 release, activation and infiltration of specific immunocompetent cell s only as glycerol esters, but not as ethyl esters.