A METHOD FOR CHRONIC MEMBRANE PLASMAPHERESIS IN THE RAT

Therapeutic apheresis as applied to humans may encompass a single trea tment or numerous treatments for disorders ranging from acute poisonin g to severe chronic autoimmune disease. However, the mechanisms of ben eficial effects of apheresis are not well characterized. Utilizing a m iniaturized hollow-fiber membrane system, we have developed a reliable technique for long-term vascular access in the rat that permits repet itive plasmapheresis. We established vascular access in 14 animals, wi th 8 and 6 rats randomized to 3- and 7-wk experimental periods, respec tively. Immunoglobulin levels of blood samples obtained immediately be fore and after each plasmapheresis were measured to examine membrane f iltration characteristics. Overall, 100% of the animals survived and 9 3% successfully completed their assigned experimental periods. Mean de crease of immunoglobulin G and M levels for 28 plasmapheresis treatmen ts in five rats was 66.9 +/- 8.1 and 61.0 +/- 7.3% (SD), respectively, indicating effective membrane filtration. This model of apheresis can be applied to several disorders in the rat, including, but not limite d to, spontaneous insulin-dependent diabetes mellitus and experimental inflammatory bowel disease.