Overall interleukin-6 production exceeds 7 mg/day in multiple myeloma complicated by sepsis.

We previously reported that injection of anti-IL-6 monoclonal antibody (mAb) in a patient with multiple myeloma (MM) induced the circulation of high amounts of IL-6 in the form of IL-6/anti-IL-6 monomeric complexes. This made it possible to estimate overall daily IL-6 production in patients in vivo, which had not been achieved in animals or humans before. In this study, estimations are given for a patient with MM who developed Escherichia coli sepsis during anti-IL-6 mAb. During the first 12 days, the overall IL-6 production was estimated at 1.5 to 2.0 micrograms/day. On day 13, serum IL-6 concentration, in the form of IL-6/anti-IL-6 complexes, increased 1000-fold and was 1.7 x 10(6) pg/ml, in relation with the development of E. coli sepsis. Overall IL-6 production was estimated to be greater than 7 mg/day, i.e. 3500 times higher than before sepsis. Serum IL-6 levels in the form of monomeric immune complexes remained very high for 20 days after sepsis indicating the persistence of very high overall IL-6 production (100 to 3500-fold greater than pre-sepsis production). This study demonstrates a considerable and persistent potential for IL-6 production in this patient during and after sepsis.