Circulating autoantibodies to a 240 kD fetal brain protein.

Antibodies (IgG and IgM) recognizing a 240 kD antigen of the cat fetal brain were found in sera of healthy people and in sera (IgG) obtained at uncomplicated delivery from the umbilical cord of the newborn infant. The method applied was immunoblotting. Using the same method, the 240 kD antigen could not be detected in the adult brain or other fetal tissues. It seems that the antigen is specific for the fetal brain. The role of the antigen and the origin of generation and significance of function of the antibodies in the circulation are the objects of our further studies.

Myelin-associated glycoprotein in the developing human retina.

The immunohistochemical presence of myelin-associated glycoprotein (MAG) in Müller cells of the developing human retina was examined with rat monoclonal antibodies to MAG and the peroxidase antiperoxidase (PAP) method of Sternberger. Retinas of various developmental stages ranging between 9-31 gestational weeks were stained. There was no staining in the retinas of 9-12-week embryos. Between 13-16 gestational weeks the staining was faint and located mostly in the inner and middle portion of the retina, primarily around the optic nerve head. After midterm, Müller cells invariably stained through all retinal layers. The staining increased gradually up to the twenty-third gestational week, when it reached the level found in the retinas of newborn children.

Circulating autoantibodies to the 200,000-dalton protein of neurofilaments in the serum of healthy individuals.

There is substantial evidence that human serum contains antibodies to many autoantigens. For example, all healthy people have autoantibodies (immunoglobulin M) to some undefined brain antigens. In this study immunoblots and immunohistochemical staining were used to detect antibodies to neural tissues in serum samples from 200 healthy people and 200 patients with various neurological diseases. Ninety-nine percent of the 400 subjects had serum immunoglobulin M and 95 percent had immunoglobulin G that bound to a 200-kilodalton protein in homogenates of neural tissues. In most cases there were no antibodies to anything else in the homogenates. The 200-kilodalton protein was the heaviest of the neurofilament triplet proteins. These observations do not support a role for antibodies to the 200-kilodalton protein of neurofilaments in the pathogenesis of neurological diseases.

Species variations in distribution of S100 in retina. Demonstration with a monoclonal antibody and a polyclonal antiserum.

The S100 protein has been found consistently in glial cells both in the central nervous system (CNS) and peripheral nervous system (PNS). However, in the retina we find substantial species variation in the distribution of this protein. Immunohistochemically, in the human retina we do not find any S100. In the rabbit retina it is present both in Müller cells and in astrocytes and in the chicken retina it is in neurons. This demonstrates how misleading it can be to use the distribution of a protein in one species to generalize about the distribution of the same protein in other species. It is also clear that even though immunohistochemical staining for the S100 protein could be used to study pathologic conditions that involve Müller cells in guinea pigs, hamster, rat, and rabbit retina it is going to be of limited value in investigations of the same conditions in the human eye.

Amino acid and protein metabolism in dorsal root ganglia of rabbits with experimental allergic neuritis.

Amino acid and protein metabolism has been studied in the dorsal root ganglia of rabbits with experimental allergic neuritis (EAN). The concentrations of a number of nonessential amino acids (glutamine, serine, aspartate, and glutamate) were reduced in the spinal ganglia of EAN animals without any comparable change in the blood plasma. The short-term influx of glycine and GABA was decreased in EAN animals, whereas that of histidine and valine was not altered. The prolonged accumulation of all the four amino acids was unchanged. These results suggest alterations in the cell metabolism of the dorsal root ganglia, rather than unspecific changes in cellular permeability. Furthermore, incorporation of tritiated valine, histidine, and glycine into proteins of EAN-ganglia in vitro was significantly increased. Autoradiography of the protein-bound [3H]-valine indicated alterations in the protein synthesis of the ganglion neurons: A decreased grain density was found in ganglion neurons of EAN animals. The increased grain densities in the affected ganglia were observed in macrophages, and possible in activated Schwann cells, over the demyelinated spots. The results suggest intraneuronal changes in the dorsal root ganglia of amino acid and protein metabolism, possibly in response to peripheral axonal injury and/or to nonspecific cytotoxic effect of active lymphocytes and macrophages.

Immunohistochemistry of retinoblastomas in humans.

We examined immunohistochemically the distribution of the neuronal-specific protein enolase (14-3-2) in normal human retina. We also examined the distribution of neuronal-specific enolase, glial fibrillary acidic protein, myelin-associated glycoprotein, and S-100 protein in seven human retinoblastomas. In normal retina neuronal-specific enolase was present in neurons but not in other cell types. The inner segments of cones stained darkly with antiserum to neuronal-specific enolase; the inner segments of rods stained either weakly or not at all. Most small round cells in all seven retinoblastomas studied stained with antiserum to neuronal-specific enolase but Flexner-Wintersteiner rosettes stained weakly or not at all. One retinoblastoma contained an area of cells that stained with antibodies to myelin-associated glycoprotein which in normal retina is found only in Müller's cells. Another retinoblastoma had an area of cells that stained with antiserum to glial fibrillary acidic protein, which in normal human retina is present only in astrocytes. All seven retinoblastomas lacked detectable S-100 protein. These results supported the conventional view that retinoblastomas are neuronal tumors although some may contain areas that show astrocytic or Müller's cell differentiation.

Myelin-associated glycoprotein in human retina.

The human retina is unmyelinated, but structural similarities have been noted between Müller cells, the main glial cell type of retina, and oligodendrocytes, the myelin-forming cells of the central nervous system. We now show that antibodies against myelin-associated glycoprotein, a minor component of central and peripheral myelin so far found only in myelin and myelin-forming cells, also stain Müller cells. Immunoblot analysis of retinal proteins indicates that the antigen detected is myelin associated glycoprotein. These results suggest a closer relationship between Müller cells and oligodendrocytes than previously suspected and raise questions about the functional role of myelin-associated glycoprotein.

Distribution of S-100 protein and glial fibrillary acidic protein in normal and gliotic human retina.

Monoclonal antibodies and polyclonal antisera were used to examine the distribution of S-100 protein in human retinas both immunohistochemically and immunochemically and to compare it to that of glial fibrillary acidic protein (GFAP). S-100 was not found in normal retinas nor in retinas with areas of reactive gliosis. GFAP was found in perikarya and processes of cells the nuclei of which were in the nerve fiber layer of normal retina. In areas of reactive gliosis there was intense staining with antiserum against GFAP extending from the internal limiting membrane to the external limiting membrane. Some of the glial cells in human retina and fibrillary astrocytes in the brain are identical in their expression of GFAP. However, absence of S-100 from both quiescent and reactive retinoglia distinguishes them from astrocytes in brain and spinal cord.

Cholinesterase activities in the autonomic nervous system of rabbits with experimental allergic neuritis: a biochemical study.

Utilizing a colorimetric method with acetylthiocholine iodide (AThCh) as substrate and eserine and ethopropazine as inhibitors, the activities of AThCh-splitting enzymes, acetylcholinesterase (AChE) and non-specific esterase (psi ChE) were determined in different structures of the autonomic nervous system (ANS) from the left and from the right sides of rabbits with experimental allergic neuritis (EAN) and controls. The total activity of AThCh-splitting enzymes showed a highly significant decrease in the ganglion nodosum and in the ganglia of the thoracal and abdominal paravertebral sympathetic chain in rabbits with clinical symptoms of ANS-involvement. Lesser but still significant changes were found in EAN-rabbits with motor symptoms but without ANS symptoms. No definite changes could be found in the superior cervical ganglia, the cervical sympathetic trunk or the interganglionic portions of the abdominal and thoracal paravertebral sympathetic chains. In samples with decreased total enzyme activities, both AChE and psi ChE appeared to decrease to approximately the same extent. This study demonstrates that the activities of AThCh-splitting enzymes are decreased in EAN in parts of ANS innervating the heart, abdominal and pelvic organs, and suggests that enzyme activities not derived from the myelin sheath may be involved in the pathogenesis of this demyelinating disease.

Cholinesterase activities in the somatic nervous system of rabbits with experimental allergic neuritis.

The allergic inflammatory disorders of the nervous tissue are associated with a complex series of cellular and humoral immune activities and they usually result at least in demyelination, but according to morphologic evidence also in secondary neuronal changes. Using the colorimetric method of Ellman et al. (G. L. Ellman, K. D. Courtney, V. Anders, and R. M. Featherstone, 1961, Biochem. Pharmacol. 7:88-95) the activities of enzymes splitting acetylthiocholine iodide (AThCh) were determined from various parts of the somatic nervous system of rabbits with experimental allergic neuritis (EAN), a primary demyelinating disease of the peripheral nerves. It was found that the total activity of AThCh-splitting enzymes was decreased already in an early phase of the disease in the dorsal root ganglia (DRG). In a well developed phase of the disease the activity of acetylcholinesterase (AChE) seemed to be decreased by 33% in the ventral roots and by a lesser amount in the DRG and the most proximal part of the sciatic nerves. The mechanism of the recorded changes may be related either to specific or to nonspecific immune events or to both. Proteolytic activity released by macrophages in the target tissue may, by inactivating the hydrolytic activity of AChE, at least partly explain these findings. Because the activity of AChE in the structures studied derives from a neuronal origin, our results provide biochemical evidence for the involvement of neurons in the sensory ganglia and of axolemma in the ventral roots in EAN.

Involvement of autonomic nervous system in experimental allergic neuritis. A light- and electron-microscopic study.

The affection of the sympathetic and parasympathetic structures of the peripheral nervous system in rabbits with experimental allergic neuritis (EAN) was demonstrated light- and electron-microscopically. The general characteristics of the microscopic findings were qualitatively similar to those previously established in the somatic nervous system, but they were less extensive. The neuronal perikarya and the axons in the autonomic nervous system (ANS) were mostly normal. Occasionally, cytoplasmic vacuoles in a few nodose ganglion neurons and some degenerating axons were seen. Other than myelin derived antigens could be operating in whole-nerve induced EAN, since inflammatory cells also infiltrated target tissue areas devoid of myelinated nerve fibers. The presence of numerous plasma cells in the target tissue suggests that local antibody formation may contribute to the destructive process. Our results establish that the ANS is frequently affected in EAN, especially in the more severe forms. Thus EAN was proved to be also in this respect a useful model for the human disease Guillain-Barré syndrome, which likewise is often complicated by autonomic dysfunctions.