PHARMACOKINETIC ALTERATION IN RATS OF RECOMBINANT INTERLEUKIN-2 (RIL-2) BY IMMUNOCOMPLEXING WITH A MONOCLONAL-ANTIBODY AGAINST RIL-2

We have investigated the pharmacokinetic alteration in rats Of recombi nant interleukin-2 (rIL-2) by immunocomplexing with a monoclonal antib ody against rIL-2. Serum rIL-2 levels after the intravenous administra tion of the immune complex at a dose of 100 mu g/rat as rIL-2 were sig nificantly higher than those after intravenous administration of rIL-2 alone at the same dose. Pharmacokinetic analysis indicated that the d istribution volume of rIL-2 decreased from 74.0 to 10.3 ml/rat, while the elimination rate of rIL-2 was little changed by immunocomplexing w ith the antibody. On the other hand, serum rIL-2 levels after the subc utaneous administration of the immune complex at a dose of 100 mu g/ra t as rIL-2 were sustained longer than those after the subcutaneous adm inistration of rIL-2 alone at the same dose, and T-max shifted from 0. 83 to 3.0h by immunocomplexing with the antibody. Pharmacokinetic anal ysis also revealed that the mean-residence-time of rIL-2 increased fro m 1.98 to 6.52h, and the area-under-the curve of rIL-2 decreased sligh tly, from 834 to 548ng.h/ml, by immunocomplexing with the antibody.