Further studies on changes in immunoglobulin G in the sera and CSF of Herdwick sheep with natural and experimental...

Previous studies showed that the concentration of IgG in serum was increased in a high proportion of Herdwick sheep in the clinical stage of natural scrapie. The present paper reports similar findings in Herdwicks with experimental scrapie in which the clinical signs were different. Further studies of the natural disease showed increased concentrations of IgG in CSF due to passive filtration from serum and not to local antibody production in the CNS. Qualitative differences in serum IgG have also been found in natural scrapie, involving a shift in the major IgG isotype from IgG1 to IgG2. The significance of these changes is not known but the limited evidence available may indicate a progressive dysfunction in certain sub-populations of lymphocytes in sheep scrapie.