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.

Adult↗

PubMedDate not supplied

The effect of serum from multiple sclerosis patients in remission on the incubated rat brain slices.

Addition of human serum to incubated rat cerebral slices induced increased generation of myelin-related, membranous fragments floating on 0.32 M sucrose. Sera from 20 healthy subjects and 19 patients with various neurological disorders were equally active in this respect. On the other hand, the myelin-degrading activity of sera from 20 multiple sclerosis patients in remission was found to be significantly elevated by about 50%. The present findings support the contention that the serum of multiple sclerosis patients possesses increased potency to induce myelin sheath alterations.

Adolescent↗

PubMedDate not supplied

Transmembrane signalling associated with ganglioside-induced CD4 modulation.

Ganglioside (GM1) treatment of CD4+ human CEM lymphoma cells stimulated transient phosphoinositide (PI) breakdown, production of inositol phosphates (IP), protein phosphorylation and rapid decrease of CD4 surface expression. A comparison between the actions of GM1 and other agents that affect these signal transduction pathways demonstrated a distinct mechanism for GM1-induced decrease of CD4. GM1 stimulated both phospholipase C activity and protein phosphorylation but had no effect on either cellular cAMP levels or tyrosine kinase activity. Phorbol myristate acetate (PMA) stimulated protein phosphorylation and caused a significant decrease in surface display of CD4. Both of these processes were blocked by pretreating cells with the protein kinase C (PKC) inhibitor H7. These results demonstrate that GM1 stimulates PI turnover and induces a rapid decrease of CD4 surface expression by processes that do not activate adenylate cyclase or tyrosine kinase. They further demonstrate that the mechanism for GM1-induced decrease of CD4 is distinct from the CD4 internalization processes mediated by PKC activity.

Adenylyl Cyclases↗

PubMedDate not supplied

Ganglioside (GM1)-treated T cells shed CD4.

In previous studies (Morrison et al., 1990), we showed that ganglioside (GM1) modulation of CD4 was associated with activation of phospholipase C and increased production of inositol triphosphate, but not with activation of protein kinase C. These results demonstrated a unique signal transduction pathway related to GM1 modulation of CD4 on T cells and raised the question as to whether intracellular Ca2+ levels and related protein kinases would be affected by GM1-induced signalling. We now show that GM1 modulation of CD4 from human T cells corresponds to decreased cellular Ca2+ without significant changes in cellular protein phosphorylation. In the course of this study we discovered that T cells challenged with GM1 exhibited new proteins in their surrounding media. Fractionation of cellular and supernatant proteins show that cells treated with GM1 released proteins with an approximate molecular weight (Mr) of 49,000. This was exclusive of GM1 protein association and GM1-induced protein phosphorylation. Immunoblots demonstrated the presence of CD4 in GM1-treated cell supernatants. Western immunoblots using anti-CD4 antibodies detected a lower Mr form (49,000) of CD4 in the supernatants of GM1-treated cells. These studies further define the unique nature of GM1 signalling relating to modulation of CD4 and demonstrate that the fate of GM1 modulated CD4, in part, involves protein shedding.

CD4 Antigens↗

PubMedDate not supplied

T-cell receptor peptide therapy in EAE and MS.

Synthetic peptides corresponding to germline TCR V beta 8.2 sequences overexpressed by Lewis rat encephalitogenic T cells are effective in the prevention and treatment of autoimmune encephalomyelitis (EAE). In evaluating optimal conditions for identifying disease-relevant target V beta genes, we found that the biased expression of V beta 8.2 was most pronounced in the CNS among activated, IL-2 responsive T cells, but was weakly reflected in the cerebrospinal fluid. Evaluation of basic protein reactive T cells from patients with multiple sclerosis revealed biased expression of V beta 5.2 and to a lesser degree, V beta 6.1. Treatment of 11 MS patients with synthetic TCR V beta 5.2 and V beta 6.1 CDR2 peptides boosted the frequency of anti-TCR reactive T cells in a majority of patients, without compromising recall immunity or causing side effects. TCR peptides may be useful in the treatment of human autoimmune diseases, providing that disease-relevant V genes can be identified.

Animals↗