Ultrastructural analysis of spinal motoneurones from mice treated with IgG from ALS patients, healthy individuals, or disease controls

Reports that ALS-IgG injected into mice results in ultrastructural abnormalities and enhanced deposition of Ca(2+) in their spinal motoneurones are unverified. To obtain verification, affinity purified IgG's from ten healthy subjects, seventeen ALS patients and eight disease controls (eg cases of LEMS, MS,) were injected into groups of mice in 4 daily doses by either i/m injection, or i/p (Total doses, 2-4 mg i/p, I mg i/m). Immunocytochemistry identified human IgG in lumbar motoneurones 48 h after the final dose. Their morphology was examined by EM and intraneuronal Ca2+ was revealed by oxylate-pyroantimonate histochemistry and its identity verified by 2 degrees emission spectroscopy. In the EMI motoneurones of non-injected mice, and mice receiving healthy IgGs had a lucent cytoplasm, intact mitochondria, and Golgi complexes comprising stacks of narrow ER. About 40% of Nissl bodies comprised alternate rER lamellae and polyribosome arrays (Type 1 structure): 10% formed polyribosome clusters (Type 3). Mitochondria, Golgi ER and presynaptic terminals contained Ca(2+) associated pyroantimonate. I/m and i/p ALS-IgG produced similar results. Some ALS IgGs (i.e. patients) produced electron dense degenerative cytology: all promoted fragmented and distended Golgi ER, polyribosmal hyperplasia, reduced numbers of Type I but raised numbers of Types 2 and 3 Nissl bodies, and a greater proportion of Golgi ER and presynaptic terminals containing Ca(2+)-antimonate. With 4/8 disease control IgGs motoneurones had normal Golgi and Nissl body organisation but dilated rER. Ca(2+) content was normal. Remaining IgGs produced normal ultrastructure. Results support claims that ALS-IgG may be cytotoxic, and that it enhances the Ca(2+) content of motoneurones and synaptic terminals. (C) 2000 Elsevier Science B.V. All rights reserved.