Chronic relapsing experimental allergic encephalomyelitis: cerebrospinal fluid cytology and a comparison with meningeal and spinal cord pathology

Lymphocytic activation in peripheral blood and cerebrospinal fluid during the course of chronic relapsing experimental allergic encephalomyelitis

A monoclonal antibody against the human interleukin-2 receptor (anti-Tac) has been found to cross-react with an antigen on the surface of guinea pig leucocytes. Cells marking with anti-Tac and with an anti-pan T cell monoclonal antibody have been quantitated in the peripheral blood and cerebrospinal fluid (CSF) of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (CR-EAE). T cells account for about 90% of peripheral blood leucocytes in all animals whilst in the CSF, T cells are the major contributor only when there is a pleocytosis. The proportion of T cells marking with anti-Tac, a measure of T cell activation, in blood and CSF of control animals is 12%, rising to 23% in blood in the post-acute phase of the disease. However, a fall in the blood Tac/T ratio to 13% occurs during the first 10 days of relapse with a subsequent rise to 30-35%. This change is related to the time after onset of relapse irrespective of the subsequent course of the disease. From first relapse onwards CSF lymphocytes show a greater level of activation than lymphocytes from paired peripheral blood samples but the proportion of Tac+ cells in CSF does not increase with increasing CSF pleocytosis. The data is consistent with migration of activated T cells from blood to CSF at the onset of relapse.

Activated T-cells and macrophages in the cerebrospinal fluid and the spinal meningeal exudate in chronic relapsing experimental allergic encephalomyelitis

An analysis has been made of the cell types which mark with monoclonal antibodies against T cells, macrophages and the IL-2 receptor (anti-Tac) in the blood, cerebrospinal fluid (CSF) and spinal meningeal exudates taken from guinea pigs in the relapse and remission stages of chronic relapsing experimental allergic encephalomyelitis (CR-EAE). Whilst the T-cell and macrophage content of blood remained unchanged throughout the course of CR-EAE, T cells accounted for the majority of the CSF pleocytosis associated with relapsing disease but both T cells and macrophages populated the meningeal exudate in substantial numbers. Activated T cells (Tac+) rose in number in blood only after the onset of relapse but formed a far higher proportion of the CSF pleocytosis or meningeal exudate than in paired blood samples. Meningeal exudate cells from Freund's adjuvant-inoculated, but not uninoculated animals, also showed an increase in Tac+ cell levels. In addition, the meningeal exudate contained a substantial number of cells which did not label with anti-T or anti-macrophage antibodies and which did not vary in absolute numbers throughout the course of disease.

Cyclosporin-A treatment of experimental allergic encephalomyelitis: changes in immunological regulation and blood-CSF barrier function

Strain 13 guinea pigs at 18-21 days of age were sensitised with spinal cord and Freund's complete adjuvant to induce experimental allergic encephalomyelitis (EAE). Treatment with cyclosporin-A (CS-A) from one day before sensitisation until from 12 to 39 days after sensitisation resulted in a suppression of the disease. Suppression was indicated by an absence or reduction in severity of clinical signs together with a lack of increase in blood-cerebrospinal fluid (CSF) barrier permeability to proteins and a lower white cell count in the CSF from treated animals. When CS-A treatment was withdrawn, clinical disease reappeared but changes in IgG concentration in the CSF indicated that intrathecal synthesis of IgG had occurred, which was not the case in the untreated disease. Modification by CS-A of the immunoregulatory processes involved in the development of EAE, provides a model to study the special conditions which operate in neuroimmunological disorders.

Quantitative analysis of the cellular constituents of the cerebrospinal fluid in chronic relapsing experimental allergic encephalomyelitis

Cerebrospinal fluid (CSF) was taken from guinea pigs in various stages of chronic relapsing experimental allergic encephalomyelitis (CR-EAE). The leucocytes in CSF samples were counted and subjected to immunocytochemical analysis using monoclonal antibodies selectively recognising guinea pig T cells, macrophages or Ia antigens. The results showed that total leucocyte numbers and the proportion of macrophages in CSF were elevated in the acute phase of CR-EAE but samples of CSF from animals in early relapse did not show a significant elevation in leucocyte count or macrophage content. In addition the level of T cell activation was higher in CSF than in peripheral blood during disease and was highest in the acute and immediately post-acute phases of the CR-EAE.

Chronic relapsing experimental autoimmune encephalomyelitis. Transient presence in blood of lymphocytes sensitised to encephalitogen at onset of inflammatory relapses

Juvenile guinea pigs were immunised with homologous spinal cord and monitored daily over a 6-month period for neurological signs of chronic relapsing experimental autoimmune encephalomyelitis (CREAE). At various times animals were killed, numbers of leucocytes in their cerebrospinal fluid (CSF) quantified, and in vitro proliferative responses of blood lymphocytes to myelin basic protein (MBP) and its encephalitogenic nonapeptide (NP) determined. After recovering from initial acute clinical signs, animals suffered at least two major spontaneous relapses separated by remission periods of 4-5 weeks mean duration. In the early chronic phase, 5-12 weeks post-immunisation (pi), 63% of the animals recovered fully from relapses, whereas relatively irreversible neurological deficits predominated in the late chronic phase. During the acute and chronic phases, there was a highly significant correlation between clinical severity and CSF pleocytosis only in animals killed within 24 h of onset of a clinical exacerbation associated with more than 100 leucocytes/microliter of CSF. Guinea pigs with this degree of CSF pleocytosis were defined as suffering an inflammatory relapse. Blood lymphocytes responsive to MBP and NP were detected only in animals killed at the onset of clinical signs of either the acute or an inflammatory relapse. This dynamic relationship suggests that migration of encephalitogen-responsive lymphocytes via the blood to the central nervous system could produce certain relapses in CREAE. However, the relative paucity of CSF leucocytes in most animals killed during relapses between 15-26 weeks pi suggests that other factors may elicit neurological exacerbations in the late chronic phase.

In vitro synthesis of immunoglobulins and autoantibodies by lymphocytes from various body compartments during chronic relapsing experimental allergic encephalomyelitis

Mononuclear cells extracted from regional lymph nodes, blood, spleen and central nervous system of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (r-EAE), adjuvant immunized and untreated controls were cultured for 16 h in microtitre plates, and culture supernatants were then used to measure IgG and IgM, as well as IgG class anti-myelin antibody production by enzyme-linked immunosorbent assays. Increased synthesis of these immunoglobulins and antibodies was found during the course of r-EAE both in intra- and extrathecal compartments. Long-term cultures carried out for 7 days gave similar results but anti-myelin, anti-myelin basic protein and IgG synthesis was most pronounced intrathecally. Agarose isoelectric focusing of supernatants from these cultures showed oligoclonal IgG. These findings indicate in vivo synthesis of autoantibodies within the target for immune attack and a partial sequestration of the immune response to this compartment.

Chronic relapsing experimental allergic encephalomyelitis. The presence in the cerebrospinal fluid of factors chemotactic for monocytes

Cerebrospinal fluid (CSF) was removed from guinea pigs with chronic relapsing experimental allergic encephalomyelitis (CR-EAE) and control inoculated animals by puncture of the cisterna magna. The fluid from 7/8 animals in relapse and 2/4 animals in remission phases of CR-EAE was found to promote the migration of peripheral blood monocytes through a 5-micron pore diameter polycarbonate membrane filter. Monocytes were also found to orient towards the migration-stimulating CSF in a gradient formed between such fluid and CSF derived from a control animal, thereby indicating the presence of a chemotactic factor. The factor responsible for promoting monocyte migration had a molecular weight of between 50 000 and 300 000 as defined by ultrafiltration. The results are discussed in relation to the known pathohistological features of the chronic relapsing disease.