title: Activation of the complement system during immunotherapy with recombinant IL-2. Relation to the development of side effects.
abstract: Therapy with high doses of rIL-2 is complicated by the occurrence of hypotensive reactions and the development of a vascular leakage syndrome (VLS). In four patients, who together received seven cycles of high doses of IL-2 (up to 12 x 10(6) U per m2 per day), and who developed these side effects, we observed an unexpected increase in plasma levels of C3a, indicating activation of the complement system. C3a levels markedly increased during IL-2 therapy from 4 nmol/liter (mean level) before therapy to 23 nmol/liter at the end of the cycle. Activation of C3 occurred via the classical pathway inasmuch as C4a levels also increased during therapy. Mean daily C3a levels correlated with signs of the VLS, such as daily weight gain (p less than 0.001) and albumin levels (inverse correlation, p less than 0.001). In five additional patients, who together received seven cycles of lower doses of IL-2 (2 x 10(6) U per m2 per day) and who did not develop a VLS, only moderate increases in C3a levels (up to 13 nmol/liter) were observed. The highest levels at the first day of the regimen (mean: 7 nmol/liter) occurred 8 h after the IL-2 infusion. Thus, administration of IL-2 induces a dose-dependent activation of the complement system in vivo, which appeared to be related to the development of side effects of this therapy, such as the VLS.
authors.affiliation: Medical Intensive Care Unit, Free University Hospital, Amsterdam, The Netherlands.
authors.forename: L G
authors.initials: LG
authors.lastname: Thijs
authors.forename: C E
authors.initials: CE
authors.lastname: Hack
authors.forename: R J
authors.initials: RJ
authors.lastname: Strack van Schijndel
authors.forename: J H
authors.initials: JH
authors.lastname: Nuijens
authors.forename: G J
authors.initials: GJ
authors.lastname: Wolbink
authors.forename: A J
authors.initials: AJ
authors.lastname: Eerenberg-Belmer
authors.forename: H
authors.initials: H
authors.lastname: Van der Vall
authors.forename: J
authors.initials: J
authors.lastname: Wagstaff
mesh_terms: D000328:Adult; D001835:Body Weight / Q000187:drug effects; D003167:Complement Activation; D015926:Complement C3a / Q000378:metabolism; D003165:Complement System Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007376:Interleukin-2 / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins
chemical_list: D007376:Interleukin-2; D011994:Recombinant Proteins; D015926:Complement C3a; D003165:Complement System Proteins