Microencapsulated islets of Langerhans retrieved from peritoneal cavity of rats three weeks after implantation had a reduced hormonal secretion and were no longer responsive to alterations in glucose levels. Activation of complement could not completely account for the observed fibrosis which was thought to be responsible for the loss of responsiveness of the encapsulated cells.
Quantitative, immunopathological, light and electron microscopic studies of superficial peroneal nerve biopsies from 31 patients with IgM monoclonal gammopathy were carried out. Six patients had Waldenström's macroglobulinemia and 25 had IgM monoclonal gammopathy of undetermined significance. Serum samples from 28 of these patients were assayed for anti-myelin-associated glycoprotein (anti-MAG) activity. Anti-MAG activity was found in 25 of the samples. There was a relationship between the widening of some myelin lamellae observed on ultrastructural examination and the serum anti-MAG activity (23 cases). Immunopathological examination showed IgM binding to myelin sheaths in 17 cases.
In a patient with Waldenström's macroglobulinaemia and peripheral neuropathy, direct immunofluorescence of a peripheral nerve revealed the presence of abundant IgM and kappa light chain deposits in the endoneurium. Electron microscopic examination showed the microtubular structure of these endoneurial deposits, which strongly suggested the presence of cryoglobulin; this was then found in the serum.
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