A PILOT-STUDY TO EVALUATE THE EFFECTS OF C1 ESTERASE INHIBITOR ON THE TOXICITY OF HIGH-DOSE INTERLEUKIN-2

In a pilot study six patients received 4 days' treatment with interleukin 2 (IL-2) [cumulative dose (CD) 264 +/- 26 x 10(6) IU m(-2)] and C1 esterase inhibitor (C1-INH) (loading dose 2,000 U, followed by 500-1,000 U twice daily). Toxicity was Compared with that ih patients given 4 days' treatment with standard (CD 66 +/- 12 x 10(6) IU m(-2)) or escalating-dose (CD 99 +/- 8 x 10(6) IU m(-2)) IL-2. IL-2induced hypotension was equivalent and complement activation was less after IL-2 + CI-INH (C3a = 10.5 +/- 3.2 nmol l(-1)) than following standard (14.1 +/- 8.4 nmol l(-1)) or escalating-dose (18.3 + 2.9 nmnol l(-1)) IL-2. This study demonstrates that C1-INH administration during IL-2 treatment is safe and warrants further study to evaluate its ability to ameliorate IL-2-induced toxicity.