On the role of sensitised T-lymphocytes in the pathogenesis of multiple sclerosis

Mechanisms of sprouting in the adult central nervous system: cellular responses in areas of terminal degeneration and reinnervation in the rat hippocampus

Neurons of the adult mammalian central nervous system are limited in their ability to regenerate in response to injury. In certain circumstances, however, such neurons can exhibit morphological plasticity (e.g. sprouting). Unilateral transection of the perforant path in the adult rat induces terminal degeneration of entorhinal axons within the molecular layer of the ipsilateral hippocampal dentate gyrus. Cholinergic (and other) afferents subsequently sprout within the denervated zone. We show that despite the breach in the blood-brain barrier at the site of the aspirative lesion, the barrier remains intact in the areas of terminal degeneration (and reinnervation), and peripheral monocytic macrophages do not infiltrate this area to participate in the degenerative and/or regenerative events. Perforant path transection does not induce expression of major histocompatibility antigens on reactive cells within the denervated zone, nor are T lymphocytes recruited to this area. T lymphocyte-deficient Nude rats exhibit normal cholinergic sprouting. Perforant path transection does induce rapid and robust proliferation of microglia, and astrocytes to a lesser extent, in areas undergoing terminal degeneration. Histological evaluation after antimitotic administration shows that this glial proliferation is not required for the subsequent neuronal sprouting events. These results show that the reparative process in this model system involves interactions between cells endogenous to the brain in a non-immune context. Knowledge of these cellular responses provides a framework from which to further investigate putative molecular signals involved in initiating the neuronal sprouting events. Discovering the cellular and molecular interactions taking place under sprouting conditions is likely to be critical for understanding the mechanisms of reactive neuronal growth and, furthermore, may provide insights as to why regeneration is so limited in the central nervous system.

CD4+, CD8+, and CD4- CD8- T cells in CSF and blood of patients with multiple sclerosis and tension headache

Two-colour flow cytometric analysis was performed on paired samples of peripheral blood (PB) and cerebrospinal fluid (CSF) of patients with untreated multiple sclerosis (MS) and, for reference, subjects with muscular tension headache (TH) using anti-CD3, anti-CD4, anti-CD8, and anti-HLA-DR monoclonal antibodies in different combinations. CD4+/CD8+ T-cell ratio was increased in CSF compared to PB in both MS patients and TH subjects to a similar extent. This was mainly due to higher CD4+ T-cell levels in the CSF compartment. The proportion of HLA-DR+ T cells was higher in CSF than PB in both MS and TH; this increase of DR+ T cells in CSF was more prominent in MS. The level of CD4+ CD8+ T cells, which represent a subset of activated T cells, was not different between CSF and PB, either in MS or in TH. The proportion of CD4- CD8- T cells, which were found generally not to be blast cells, was lower in CSF compared to PB in both patient groups. However, their CSF level was higher and their PB level lower in MS compared to TH. Results point to an accumulation of activated T-helper cells in the CSF of both MS patients and healthy subjects. Fetal-type CD4- CD8- T cells bearing the unusual T-cell receptor gamma/delta seem to be selectively recruited to the CSF of MS patients.

Peripheral blood lymphocyte sub-populations and multiple sclerosis

Serial studies of lymphocyte sub-populations in patients with multiple sclerosis (MS) show periodic reductions in OKT8 cells (%). This alteration is neither immunologically nor disease-specific and also occurs in some apparently healthy normal individuals. In twice-monthly serial studies of lymphocyte sub-populations carried out over a 6-month period, we have found significant reductions in OKT8 cells on at least 2 occasions in 9/9 patients, 7/7 spouses and 3/11 siblings, but rarely in unrelated controls living in the same city. Abnormalities in these unaffected people occurred at the same time as those seen in their affected relative. Cyclical reduction in OKT8 cells is probably one factor associated with susceptibility to MS, perhaps only abnormal in terms of the frequency and duration with which it occurs, and may be related to environmental conditions affecting patients with MS and their close contacts but not most other unaffected individuals.

Lymphocyte subpopulations in patients with multiple sclerosis

Using monoclonal antibodies, peripheral blood helper/inducer (OKT4) and cytotoxic/suppressor (OKT8) lymphocytes were measured in 14 normal controls, 36 patients with multiple sclerosis at different stages of the disease and 15 patients with isolated optic neuritis. Thirty-four of these individuals were studied on two or more occasions at intervals up to 340 days. Patients with multiple sclerosis in relapse had low levels of OKT8 cells (14.07% +/- 3.79) compared with controls (29.42% +/- 4.69) and this abnormality returned to normal within approximately one month of the onset of new symptoms. Further changes occurred with new relapses. Low OKT8 cells were also found in patients with isolated optic neuritis (18.76 +/- 3.71) or progressive multiple sclerosis (19.91% +/- 7.96); the same pattern of recovery was seen in these two groups as in patients with multiple sclerosis in relapse. In 25% patients studied on two or more occasions after an episode of demyelination abnormalities of lymphocyte subpopulations occurred which were not accompanied by new clinical symptoms or signs. Fluctuations of this kind did not occur in controls. The findings have implications for the pathogenesis and management of patients with multiple sclerosis.

Experimental allergic encephalomyelitis. Early T cells and TG cells are separate subpopulations

To investigate whether previously described fluctuations in circulating early T cell levels reflected a change in suppressor activity, early T cell and TG cell values were determined in guinea pigs with acute and chronic experimental allergic encephalomyelitis (EAE) and normals. It was found that while both subpopulations showed similar changes in EAE, particularly decreases during periods of clinical worsening, changes in the two subpopulations were not always synchronous. Also, similar levels of TG cells could be found both in isolated early and isolated late (total) T cells. These two lines of evidence indicate that early T cells and TG cells are heterologous populations and that early T cells do not reflect suppressor activity, findings in accord with a similar, recent study on multiple sclerosis.

Sensitization of cerebrospinal fluid and peripheral blood lymphocytes to myelin basic protein in multiple sclerosis

Cerebrospinal fluid (CSF) and peripheral blood (PB) lymphocyte sensitization to rabbit myelin basic protein (MBP) in 44 multiple sclerosis (MS) patients, 21 patients with other neurological diseases (OND) and 14 persons with neurosis was studied with the antigen-active rosette forming cells (Ag-ARFC) assay. The frequency of sensitization of CSF lymphocytes to MBP in groups of MS patients in the relapse stage and the chronic progressive stage was higher than in the group of MS patients in the stable stage and the OND patients. None of the healthy subjects showed a positive reaction with MBP. In BP there were no differences in the incidence of sensitization to MBP between patients in various stages of the disease, but it was higher than in the group of patients with OND and neuroses. In the patients who had suffered from MS for less than 4 years, sensitization to MBP was more common in CSF lymphocytes than in BP lymphocytes. The results suggest that primary sensitization to MBP occurs in CSF, and is probably secondary to myelin damage. However at present it is difficult to determine the extent to which sensitization of CSF and PB lymphocytes to MBP play a role in further demyelination processes.

Cell-mediated immunity in multiple sclerosis as determined by sensitivity of different lymphocyte populations to various brain tissue antigens

Peripheral blood lymphocytes from patients with multiple sclerosis (MS) or other neurological diseases and from healthy individuals were separated by density gradient sedimentation into several subfractions. Individual cell populations were cultured in the presence of several human brain tissue antigens. In comparison to controls, mononuclear cells with a density of less than 1.077 gm/cm3 from MS patients displayed a significantly increased sensitivity after incubation with purified human myelin basic protein (MBP) but not with other brain tissue antigens. In particular, the lymphocytes of patients suffering from MS for more than four years reacted positively with MBP, suggesting that the reaction dependent. No difference between MS patients and controls in sensitivity to any brain tissue antigen could be detected with cells of lower density (i.e., 1.073 to 1.069 gm/cm3 or less than 1.069 gm/cm3). Comparable lymphocyte activity was found to antigens isolated from both MS and control brain tissue. These results suggest that patients with chromic progressive MS have a secondary immune activity to MBP.

Multiple sclerosis-lymphocyte transformation with multiple sclerosis and normal brain myelin basic protein and subcellular fractions

Possible sensitisation of peripheral blood mononuclear cells from multiple sclerosis (MS) patients was studied in the presence of both normal and MS brain subcellular fractions. Myelin, synaptosomal and microsomal fractions and myelin basic protein were prepared by sucrose density gradient centrifugation from normal and MS brain. These preparations were added to mononuclear cell microcultures from the peripheral blood of nine acute and six chronic MS patients, 10 patients with other neurological diseases and 10 normal subjects. There was no significant increment in the peripheral blood mononuclear cell transformation of any of the acute MS patients with any of the fractions. Therefore there is no evidence that immunity to antigens in any of the fractions of MS or normal brain is of primary pathogenetic importance. A small increment in peripheral blood mononuclear cell transformation in the presence of several fractions was observed in two of six chronic MS patients, which might indicate the development of a secondary immune response after prolonged disease.

Multiple sclerosis: heterology among early T cells and Tg cells

Circulating early T cells and TG cells were estimated simultaneously in 100 patients with multiple sclerosis and 21 controls. The results were analyzed from individual patients, from patients grouped according to disease activity, and from some patients studied longitudinally. Previously documented fluctuations in these two T cell populations were confirmed. By comparing the fluctuations and by examining the distribution of TG cells in suspensions of isolated early and isolated late T cells, it was found that TG cells are a T cell subpopulation distinct from early T cells.

Multi-sialo brain gangliosides are powerful stimulators of active E-rosetting lymphocytes from multiple sclerosis patients

Peripheral blood T lymphocytes from all of 14 patients with clinically definite multiple sclerosis (MS) were significantly stimulated by MS brain gangliosides in the active rosetting of sheep erythrocytes. Fractionated mono- and disialogangliosides were devoid of any stimulating effect on MS lymphocytes whereas the trisialoganglioside GT1 and to a greater extent the tetrasialoganglioside GQ1b were fully effective at a dose as low as 2 x 10(-18) moles. Gangliosides extracted from MS brains or from MS brain myelin were far more effective than gangliosides derived from control human brains or from bovine and mouse brains, suggesting the importance of highly sialylated gangliosides occurring to a greater extent in MS brain as previously reported. Lymphocytes from only 3 out of 24 other neurological patients were stimulated by the slow migrating gangliosides in the same way, but none of 32 healthy subjects responded to these gangliosides in the active E-rosette test. Lymphocytes from 5 to 8 patients with unilateral optic neuritis reacted positively to brain gangliosides by rosette formation, several weeks before a similar reaction to myelin basic protein was evident. Our data are compatible with a release of gangliosides during demyelination or other CNS degenerative processes occurring in multiple sclerosis.

Annotation. Recent biochemical and immunological observations in multiple sclerosis

As there is evidence of early biochemical and histological changes in the normal-appearing white matter in MS, which appear to be independent of or precede demyelination, the formation of plaques may be incidental to a more primary lesion. The finding of persistently increased levels of IgG in the CSF of patients with MS points to an ongoing immune reaction in the CNS, possible against an infective agent; but virus-specific antibodies account for only a small proportion of IgG in the CSF. Furthermore, in vitro assays of T cell function suggest that there may be a regulator T cell defect in MS. Salk and colleagues (1980) have postulated that MS may be a disorder, attributable to multiple inducing agents, which is potentiated through deregulation of lymphocyte function.