Background: Increased serum levels of proinflammatory cytokines may contribute to the organ damage in active ANCA-positive renal vasculitis (ANCA-A). Plasma exchange (PE) may influence the activity of vasculitis not only by removal of pathogenic autoantibodies, but also by lowering of serum levels of circulating cytokines.
Methods and results: Serum levels of IL-1, IL. 1ra, IL-6, IL-8, ICAM-1 and VCAM-1 were measured using ELISA in 10 pts with active ANCA-positive renal vasculitis (5 pts with Wegener's granulomatosis-WG, 5 pts with microscopic polyangiitis-MPA) during the course of therapeutic PE. Cytokines and adhesion molecules were measured in samples of serum obtained in the beginning and at the end of the 1st, 3rd and 5th PE and in the samples of filtrate obtained during the same PE. Pts with ANCA had before the 1st PE in comparison with controls higher serum levels of IL-1ra, IL-8, ICAM-1 and VCAM-1. There were increased serum levels of IL-6, IL-8, ICAM-1 and VCAM-1 in pts with MPA and increased serum levels of all measured cytokines and adhesion molecules in pts with WG. At the end of the course of PE there was the decrease of serum levels of IL-ira and VCAM-1 in pts with ANCA and IL-1ra and ICAM-1 in WG. Single PE led in pts with ANCA only to the decrease of serum levels of ICAM-1 and VCAM-1. On the other hand, there was no change of serum levels of IL-1 and IL-8 serum levels of IL-1ra and IL-6 even increased at the end of single PE, in spite of high levels of all cytokines and adhesion molecules in plasmafiltrate.
Conclusions: Serum levels of soluble adhesion molecules decrease after PE, but serum levels of proinflammatory cytokines are not reduced even by the course of PE. Removal of these substances by PE is obviously counteracted by their increased production, possibly further stimulated by the contact of blood with synthetic membrane. Insufficient influence of PE on the elimination of proinflammatory cytokines may partially explain its limited effect in some patients with ANCA-positive renal vasculitis.