Mark E. Gurney

Inhibition of Terminal Axonal Sprouting by Serum from Patients with Amyotrophic Lateral Sclerosis

To investigate the pathogenesis of amyotrophic lateral sclerosis, we compared the effect of serum from patients with this disease on the regenerative sprouting of terminal axons in botulinum-treated mouse gluteus muscle with the effects of serum from controls and from patients with diabetic peripheral neuropathy. Serum from 9 of 19 patients with the sporadic form of amyotrophic lateral sclerosis and from 2 of 6 patients with the familial form caused a reduction in the proportion of sprouting terminal axons, as compared with that found in muscles treated with serum from controls or diabetic patients. Immunoglobulin from patients with amyotrophic lateral sclerosis, when tested on immunoblots, recognized a 56-kilodalton protein secreted by denervated rat diaphragm muscle; rabbit antiserum raised against this protein also suppressed terminal axonal sprouting. Thus, we have detected an antibody in the serum of patients with amyotrophic lateral sclerosis that inhibits sprouting of neurons and subsequent reinnervation of skeletal muscle. Whether this antibody is of primary pathogenic importance or represents a secondary response to neuromuscular destruction is not known. In either case, serum from patients with amyotrophic lateral sclerosis may provide reagents for studies of the trophic communications between muscle and motor neurons.

Immunology of amyotrophic lateral sclerosis.

ConclusionThe antibody detected in the ALS sera with suppressive activity for terminal sprouting is likely directed against an antigen that is normally sequestered. Tolerance to the 56 kd antigen described here is not exhibited in rats, as syngenic immunizations induce an immune response (M. E. Gurney, unpublished observation). Freshly denervated muscle secretes very low amounts of the 56 kd antigen, and the level of secretion rises 2–3 days after denervation in vivo. Of the few antecedent events associated with ALS by case studies, mechanical injuries, participation in physical activities, or bone fractures might all produce nerve damage or periods of limb immobilization [48]. Similar physical insults are stimuli for sprouting in animal models [13, 39], and might result in elevated secretion of sprouting factor, resulting in induction of an immune response in susceptible individuals.The antibodies detected in this study could arise as a secondary response to neuromuscular destruction, as occurs following tissue injury in many organs. The absence of inhibitory activity in sera of patients with neuropathy suggests that denervation per se need not give rise to development of such antibodies, although the extent of denervation and muscle atrophy in the ALS patients was, in general, markedly greater than in patients with neuropathy. Whether sprouting inhibitory antibodies prove to be of primary pathogenic significance, or are only a secondary phenomenon, they provide potentially significant reagents with which to elucidate the existence and nature of human motor neuron growth factors.

Neuroleukin: basic biology and functional interaction with human immunodeficiency virus

Surprising molecular parallels between the brain and the immune system have emerged in recent years. Most surface antigens on T-cells or B-cells that are important for recognition of antigen or for cell-cell interaction (e.g., the T-cell and B-cell antigen receptors, the products of the MHC lod, and the CD4 and CD8 markers of T-cell subtypes) are members of the immunoglobulin supra-gene family (Hunkapiller & Hood 1986). Some members of the family, notably Thy1 and the MRC 0X2 antigen, are expressed on both lymphocytes and neurons (Williams & Gagnon 1982, Clark et al. 1985). The immunoglobulin gene motif also is present in two proteins important for cell adhesion within the nervous system, the neural cell adhesion molecule (N-CAM) and myelin associated glycoprotein (Cunningham et al. 1987, Arquint et al. 1987). The utilization of the immunoglobulin gene motif by both the brain and the immune system possibly indicates a common evolutionary origin for the two systems. Perhaps primitive sensory cells were the precursors of both the nervous system and the immune system, and indeed, one could view the immune system as an internal sensory system for antigens. Maybe it is not so surprising that the logic of their construction and the recognition molecules that these systems use have many common features. Soluble mediators of the immune response also have activity on neural cells. Interleukin-1, for example, is a mitogen for astrocytes (Giulian et al. 1985) and also activates central mechanisms controlling elevation of body temperature (Fontana et al. 1984a). More remarkably, gamma-interferon (IFN-y) induces la expression on astrocytes (Wong et al. 1984) which then enables astrocytes to function as antigen-presenting cells (Fontana et al. 1984). Antigen presentation

Quantitative immunoassay of recombinant murine neuroleukin

A eukaryotic, transient expression system was used to produce recombinant neuroleukin, a growth factor for neurons. Neuroleukin in media conditioned by transfected monkey COS-1 cells was purified to homogeneity in one step by high-performance cation-exchange chromatography. Purified neuroleukin was used to establish a quantitative two-site enzyme-linked immunosorbent assay and the accuracy of the assay was confirmed by analytical high-performance liquid chromatography. The amount of recombinant neuroleukin secreted by the transfected COS-1 cells and the content of endogenous neuroleukin in various murine cell lines was determined. Neuroleukin levels were nearly undetectable in Balb/3T3 embryo cells, intermediate in several leukocytic cell lines and highest in mouse LBRM-33 T lymphoma cells. Maximal survival of sensory neurons was obtained with approximately 10(-9) M recombinant neuroleukin although tissue derived neuroleukin appeared to be significantly more active. Dialysis of the transfected COS-1 cell conditioned medium resulted in increased neuroleukin bioactivity, while binding to the cation-exchange column reduced bioactivity. The expression and purification of the recombinant protein and the detection of natural sources expressing high levels of neuroleukin will greatly facilitate studies of its biological effects.

Neuroleukin secretion is highly regulated in T-cells but constitutive in C6 glioma cells

were in the acute phase of the disease and out of therapy. The methods used have been previously described (Licastro et al., Carcinogenesis, 3: 45, i982). No significant difference as far as unscheduled DNA repair synthesis and survival a÷ter gamma radiation or exposure to high temperature was found between PBL from NS patients and controls. Our data are in agreement with those of Robbins (In: Cellular responses to DNA damage, pp. 671-700; Friedberg and Liss eds., New YorK, 1983), who studied post-X ray viabi l i ty in NS lymphoblastoid lines and do not support the hypothesis that a DNA repair defect is present in NS PBL as suggested by Gipps and Kidson. The hypothesis may be put forward that the previously reported genomic instabi l i ty is likely of viral origin and not due to a genetic DNA repair defect in NS.