Methods: Side effects of IVIG will be monitored by use of a standardized questionnaire distributed to the nursing staff and the patients (please see attachment). Complement activation will be monitored before and after the IVIG-infusion using standard C3, C4 and 50% complement hemolytic activity (CH50) assays. Serum levels of immunoglobulin A, immunoglobulin M and immunoglobulin G will be quantified before and after IVIG-infusion. In phase A of the study we aim at including approximately 40 patients (which would be predicted to include approximately 20 patients with clinical symptoms). In phase B we would randomize these same patients into two groups of similar sizes, the first group receiving standard unfiltered IVIG infusions, the second group receiving 0.2um filtered IVIG infusions