[Immune complex formation and complement changes in osteosarcoma patients treated with high-dose methotrexate]

Patients with osteosarcoma frequently have elevated immune complex levels, which are correlated with disease activity and tumor volume. During treatment with high-dose methotrexate (MTX) some patients develop specific immune complexes containing MTX. These patients suffered from anaphylactic reactions. To study the influence of MTX on immune complex formation we looked for polyethyleneglycol (PEG) precipitable and C3b-binding immune complexes in the sera of 10 children with osteosarcoma during treatment according to the COSS 80 protocol. Sera were obtained before, 24, 48 and 72 hours after MTX-infusion. Furthermore we analysed changes of the complement system in the same way. The minority of the patients developed PEG-precipitable immune complexes. C3b-binding IgG complexes were observed at the beginning and at the end of treatment. High levels of immune complexes at the end of chemotherapy were correlated with a poorer prognosis. There was no relationship between MTX-infusion and immune complex formation. No significant changes of the complement system during MTX-infusion were found. The complement analysis were of no prognostic value concerning the osteosarcoma.