GAMMA-GLOBULIN AFFINITY FOR NORMAL HUMAN TISSUE OF THE CENTRAL NERVOUS SYSTEM

B cells and antibodies in CNS demyelinating disease

There is much evidence to implicate B cells, plasma cells, and their products in the pathogenesis of MS. Despite unequivocal evidence that the animal model for MS, EAE, is initiated by myelin-specific T cells, there is accumulating evidence of a role for B cells, plasma cells, and their products in EAE pathogenesis. The role(s) played by B cells, plasma cells, and antibodies in CNS inflammatory demyelinating diseases are likely to be multifactorial and complex, involving distinct and perhaps opposing roles for B cells versus antibody.

Non-specific binding of normal human IgG, including F(ab')2 and Fc fragments, to embryonic rat brain neurons and human cortex synaptosomes

Binding of normal human IgG to embryonic rat brain neurons was quantitated by flow cytometry. IgG binding was linear between 0.05 and 1.5 mg/ml; slight binding was detectable even at normal cerebrospinal fluid concentrations. Similar binding curves were obtained for purified Fc and F(ab')2 fragments from normal human IgG. Normal human IgG also bound to synaptosomes (resealed nerve terminals) from human cerebral cortex. However, competition assays utilizing 125I-IgG showed no evidence for specific binding. This study indicates that the specificity of putative anti-neuronal antibodies should be confirmed by competition assays as for other receptor-ligand binding.

Binding of swine IgM immunoglobulins to peripheral nerve myelin sheaths in electron microscopic immunocytochemistry

The IgM fraction of normal swine serum (NSS) was found to adhere to human peripheral nerve myelin sheaths from randomly selected neuropathies and control nerves in electron microscopic immunocytochemical assays. The reaction could be blocked by preincubation with undiluted fetal calf serum (FCS), whereas endoneurial background staining was already abolished by preincubation with 10% FCS. Only the IgM, but not the IgG or the IgA fraction of NSS adhered to peripheral nerve tissue. Such strong adherence of one of the components in an immunocytochemical assay may be a source of misinterpretation. Binding of swine IgM to human peripheral nerve myelin has not been described before and is of interest in the discussion about IgM binding to myelin-associated glycoprotein in IgM gammopathies.

Double ligand ELISA technique for the estimation of antibodies to brain tissue antigens in patients with neurological disorders

A double ligand enzyme-linked immunosorbent assay (ELISA) has been developed to detect antibodies against brain tissue antigens in the sera of patients with neurological diseases. The sera were tested on human white matter homogenate. The technique consists of successive incubations with the human serum to be tested, rabbit immunoglobulin G (IgG) to human immunoglobulins (Ig), alkaline phosphate-labeled protein A and alkaline phosphatase substrate. This procedure has the advantage of increased sensitivity compared to the classical ELISA. Application of this procedure to the sera of patients with neurological diseases showed that the unspecific binding is very low and the results are reliable. Moreover the test allows the detection of antibodies to chemically different antigenic structures that can occur in a variety of neurological diseases.

Immune responses to myelin antigens in multiple sclerosis

Multiple sclerosis is considered to be a putative immunopathologic disease and there has been considerable effort over the years to prove an autoimmune etiology for it. To date, the evidence is all indirect and there is no proof of either antibody and/or cell-mediated hypersensitivity to any single identifiable CNS constituent whether a constituent of normal CNS or specific to the CNS of MS patients.

Fixation-dependent cytoplasmic false-positive staining with an immunoperoxidase method

Fixation-dependent nonspecific staining with the unlabeled immunoperoxidase (PAP) method was studied using paraffin-embedded human spleen sections fixed in various fixatives; the specific primary antiserum was omitted or nonimmunized normal rabbit serum was used. Strong cytoplasmic staining of polymorphonuclear leucocytes and macrophages was found after fixation in acetone, alcoholic formalin (94% alcohol) and absolute ethanol. This staining was mainly produced by the second layer of the PAP method. The most probable explanation of this phenomenon is nonspecific protein-immunoglobulin interaction as a result of alcoholic or acetone fixation of the sections. The present findings point to the importance of controls for each case under study to avoid false-positive interpretations.

Multiple sclerosis: capping of surface immunoglobulin G on macrophages engaged in myelin breakdown

Macrophages were examined for immunoglobulin G (IgG) and albumin in actively demyelinating lesions in two patients with multiple sclerosis (MS) using the peroxidase-antiperoxidase immunocytochemical technique. In both cases, macrophages were present that stained for cytoplasmic or surface IgG or both. In one case, in which the tissue was rapidly fixed in chilled fixative, macrophages located among myelinated nerve fibers at plaque margins, but not elsewhere in the plaque, revealed surface IgG in the form of caps restricted to one or both poles of the cell. These caps were absent in sections stained for albumin. Because capping implies the presence of a multivalent ligand close to the cell surface and because cap formation was observed only in macrophages contacting myelin sheaths, we suggest that antimyelin antibody cytophilic for macrophages may be present in the central nervous system in MS, and that immune ligand-mediated phagocytosis may play a role in myelin breakdown in the disease. This study provides the first direct evidence that IgG participates locally in myelin breakdown in MS.

Multiple sclerosis serum and cerebrospinal fluid immunoglobulin binding to Fc receptors of oligodendrocytes

Suspensions of bovine oligodendrocytes were used to study the immunofluorescent staining properties of sera from multiple sclerosis (MS) patients and normal individuals. All sera (14 MS patients, 8 patients with other neurological diseases, and 11 normal individuals) showed positive oligodendrocyte staining by indirect immunofluorescence. Staining persisted after extensive absorption of sera with bovine liver to remove nonspecific binding. Similar findings were obtained for cerebrospinal fluid from all 5 MS patients as well as all 5 patients with other neurological diseases. In additional studies to determine if binding is mediated by the Fc fragment of IgG, results were: (1) ultracentrifuged normal and MS sera failed to react with oligodendrocytes, (2) positive staining with oligodendrocytes was observed after heat aggregation of IgG, (3) ox red blood cells, complexed with antibody, reacted with oligodendrocytes to produce strong rosette formation, and (4) the rosette formation could be blocked by prior treatment of oligodendrocytes with heat-aggregated IgG. The studies fail to support a previous claim for specific binding of immunoglobulins to oligodendrocytes in MS. However, they confirm and extend previous findings that the binding of IgG to oligodendrocytes may not necessarily be an antigen-antibody reaction. Therefore, adherence reactions with a putative antibody must exclude Fc-mediated binding.

Antibody-dependent cellular cytotoxicity in multiple sclerosis

The blood serum of patients with multiple sclerosis (MS) was capable of recruiting autologous as well as normal mononuclear leucocytes in specific antibody-dependent cellular cytotoxicity (ADCC) of rat glial tumor CCL 107/C6 cells. The gliotoxic ADCC activity of MS patients was significantly higher than that of normal persons and patients with other neurological diseases. MS serum alone or in combination with guinea pig complement was not cytotoxic for glial targets, and MS leucocytes alone displayed only nonspecific natural killer (NK) cell activity, which did not differ from that of normal persons. MS ADCC activity was tissue-specific for glial cells, being almost negligible for embryonic human lung fibroblasts and nonspecific for HeLa cells. Gliotoxic ADCC activity was higher in more severely disabled MS patients than in those who were less disabled. Patients with chronic progressive MS displayed the most significantly raised ADCC activity against glial cells, while patients in a stationary state had almost normal ADCC activity.

Immunoreactivities of gastrin (G-) cells. I. dilution-dependent staining of G-cells by antisera and non-immune sera

Results of immunocytochemical studies reported by several laboratories suggest that gastrin (G-) cells of the stomach show immunoreactivities for various pituitary hormones (ACTH, met-enkephalin, beta-endorphin and growth hormone) in addition to gastrin. By reinvestigating the immunocytochemistry of G-cells we found that these cells exhibited reactivities towards a variety of antisera against enteric, pancreatic and hypophyseal hormones. Gastrin cells can also be "immunostained" by antisera towards proteins unrelated to any peptide hormones (e.g. alpha-fetoprotein antiserum) and by nonimmune sera. Thus the specificity of immunocytochemical findings in G-cells seems to be uncertain. According to our findings the polyvalent immunoreactivities of G-cells may be caused by a distinct binding capacity for IgG molecules. This binding of IgG to G-cells seems to be mediated by the Fab fragments of the IgG molecules which may behave like a basic dye and therefore "immunostain" anionic components within G-cells. Thus the significance of the immunocytochemical proof of peptide hormones within G-cells is limited unless extended specificity controls have been performed. The results of specificity controls performed in this study (adsorption controls, use of ascending dilutions of the primary and secondary antisera, comparison of crude antisera and affinity chromatographically purified antibodies) suggest that corticotropin-lipotropin related peptides are not contained in G-cells.

Oligodendrocyte staining by multiple sclerosis serum is nonspecific

The immunofluorescent staining properties of 65 serum samples from 54 patients with multiple sclerosis (MS), 63 samples from 55 patients with other neurological diseases (OND), and sera from 14 healthy normal individuals were examined on frozen sections of bovine and human brain. When tested on bovine brain sections, positive oligodendrocyte staining was present in 63% of MS sera, 43% of OND sera, and 29% of normal sera. The percentages were lower with human brain tissue. Astrocyte and myelin staining was common. F(ab')2 fragments purified from selected positive and negative MS and control sera gave no staining, though IgG fractions from the same sera prior to pepsin digestion gave positive staining. When tested against antihuman IgM and IgA conjugates, the same positive sera and their IgG-depleted globulin fractions gave minimal or no staining. These results indicate that oligodendrocyte staining is not specific for MS, is not due to specific antibody, and is probably the result of nonspecific binding to Fc receptors.

Antibodies to oligodendroglia in patients with multiple sclerosis

We demonstrated antibodies to isolated oligodendrocytes and to oligodendroglia in brain sections by indirect immunofluorescence technic in serums of 19 of 21 patients with multiple sclerosis. We also found such antibodies in three of five patients with subacute sclerosing panencephalitis and one of four patients with acute disseminated encephalomyelitis, but not in patients with other neurologic diseases or normal persons. The antibodies were absorbed by preincubation of serum with isolated oligodendrocytes or whole white matter, but not with purified myelin or liver tissue. Immunofluorescent staining was blocked by either rabbit anti-oligodendrocyte serum or non-fluoresceinated goat anti-human immunoglobulin. These findings suggest that antibodies to oligodendroglia are distinct from antibodies to myelin and that demyelination in multiple sclerosis could be a consequence of an immunopathologic reaction directed against oligodendroglial cells.

Immunofluorescence studies of intra cytoplasmic immunoglobulin binding lymphoid cells (CILC) in the central nervous system. Report of 32 cases including 19 multiple sclerosis

In 32 cases of human neurological disorders, including 19 cases of Multiple Sclerosis, an analysis was performed on formalin fixed paraffin embedded brain tissue by using fluorescein labelled antibodies and Nomarski optics. This method, which allows the reduction of technical artifarcts, permitted to establish the presence of intracytoplasmic immunoglobulin binding lymphoid cells with IgG and IgA, more rarely IgM, in the majority of the multiple sclerosis cases. This supports the theory of the intrathecal secretion of antibodies within the central nervous system but does not allow to explain the function of those B. Lymphocytes. The same immunological picture was found in Subacute Sclerosing Panencephalitis. On the contrary, it was different in Progressive Multifocal Leucoencephalopathy.

Antimyelin antibody in multiple sclerosis: no change during immunosuppression

We studied retrospectively levels of antimyelin antibody in a group of 13 multiple sclerosis patients who underwent a clinical trial of long-term, high dose (2.0-4.5 mg/kg/day) azathiaprine therapy. In apparent contrast with collagen vascular disease associated with antitissue antibody, azathiaprine therapy was not associated with significant change in titres of antimyelin antibody. Variation of titre of antimyelin antibody in apparent association with disease activity continued during therapy. No significant changes occurred in levels of serum immunoglobulins.

Glutamine synthetase: glial localization in brain

Light microscopy immunohistochemical techniques were used to examine the distribution of glutamine synthetase in rat brain. Glutamine synthetase was found to be localized in the glial cells. Neuronal cell bodies, endothelial cells, and choroid epithelium contained no enzyme. The findings indicate that glia have a crucial role in glutamic acid, gamma-aminobutyric acid, and ammonia metabolism in brain.

Immuno-electron microscopic localization of immunoglobulins in amyloid fibrils of senile plaques

Amyloid fibrils in senile plaques of the brain of patients with senile dementia or Alzheimer's disease combined specifically with horseradish peroxidase (HRPO)-labeled rabbit anti-human IgG. Light and electronmicroscopic immunoperoxidase technique was used to prove this. The fact may mean that immunological factors were involved in the pathogenesis of amyloid fibrils in the senile plaques, and probably also in that of senile dementia or Alzheimer's disease.