Résumé : Intravenous injection of recombinant interleukin-2 (r-Met-hu-IL-2(Ala-125)) and LAK cells induced dramatic changes of lipoproteins in 12 patients with advanced cancer. After r-IL-2 injection (1) total cholesterol was reduced by 47% as a mean, LDL-cholesterol by 62%, HDL-cholesterol by 77%; (2) the triglyceride/cholesterol ratio was greatly increased (352%); (3) apolipoproteins B, A-I and A-II showed a mean reduction of 26%, 55% and 51%, respectively; and (4) very low density lipoproteins relatively increased, and HDL were separated into two definite fractions (I and II). LAK cell administration accentuated all the above effects and in most patients, HDL-fraction I almost completely disappeared. An action on hepatic synthesis of acute phase proteins is pointed out by the increase in C-reactive protein and apolipoprotein S concentrations contrasting with an unexpected reduction of fibrinogen. Surprisingly the drastic changes caused by treatment were quickly and completely reversible. © 1988.