Membrane plasma exchange in experimental allergic neuritis: effect on antibody levels and clinical course

The effect of membrane plasma exchange on the course of chronic experimental allergic neuritis in rabbits is described. Using miniature membrane plasma separators conscious animals were treated with 4 exchanges over 5 days removing one plasma volume per procedure and using a non-immunogenic gelatin plasma solution as replacement. Comparisons of clinical scores between control and treated groups indicated that treated animals received significant benefit from plasma exchange (day 1 post-treatment P less than 0.002; day 3 post-treatment P less than 0.01). However, relapse was observed in all plasma exchanged animals such that by day 8 post-treatment there was no significant difference in clinical scores between the two groups. Quantitation of anti-myelin IgG and IgM by ELISA assay showed that 55-60% of circulating antibody was removed per exchange. Rapid post-exchange antibody rebound was observed for both IgG and IgM so that pre-exchange levels were re-established within 24-48 h. However, no significant overshoot in circulating levels of anti-myelin IgG nor IgM could be observed. It is probable that long-term remission as a result of therapeutic plasma exchange is a function of effective circulating plasma removal and if present, the suppression of ongoing antigenic stimuli.