Phenotypic and functional properties of gamma delta T cells from patients with Guillain Barré syndrome

T Cell Response in Acute Motor Axonal Neuropathy

There is evidence that in the acute axonal motor neuropathy (AMAN) subtype of Guillain-Barré syndrome antibodies to gangliosides, produced through molecular mimicry by antecedent Campylobacter jejuni ( C. jejuni) infection, attack gangliosides expressed in human peripheral nerve axolemma, inducing a primary axonal damage. The aim of this study is to investigate whether the T cell response has a role in AMAN pathogenesis. We isolated monocytes from 4 healthy subjects and 5 AMAN patients with antecedent C. jejuni infection and antibodies to GM1 and/or GDla gangliosides. Immature dendritic cells expressing CD1 molecules cultured with autologous T cells were stimulated with 2 lipopolysaccharides (LPSs) extracted from C. jejuni strains containing GM1 and GDla-like structures and with GM1 and GDla. The T cell response to LPSs and to gangliosides was determined by measuring the release of IFN-γ and TNF-α. We observed a T cell response to both LPSs in controls and AMAN patients, whereas only AMAN patients showed T cell reactivity to gangliosides GM1 and GD1a with a tight correlation between T cell reactivity to the ganglioside and individual antibody responses to the same ganglioside. T cells responding to gangliosides were CD1c-restricted CD8 positive and CD27 negative. These findings indicate a contribution of cellular immunity in the pathogenesis of AMAN. A possible role for ganglioside-reactive T cells might be to facilitate the production of antibodies against gangliosides.

Reduced circulating CD4+CD25+ cell populations in Guillain–Barré syndrome

Guillain-Barré syndrome (GBS) is a monophasic inflammatory disease considered to be due to autoimmunity. In order to test the hypothesis that the disease is associated with a perturbation of the circulating lymphoid cell population, we tested the mononuclear cells from the venous blood of 21 patients with Guillain-Barré syndrome (GBS) and 20 healthy controls by flow cytometry. The proportions and numbers of B and T lymphocytes, and CD4, CD8, double negative and gammadelta T cell subsets and numbers of monocytes were not significantly different in the patients compared with the controls. However, the number and proportion of CD4+CD25+ cells were reduced in acute GBS (mean number 61.7 cells/microl, 95% CI 42.9-80.4 and mean percentage 4.6%, 95% CI 3.8-5.4) compared with controls (mean number 99.8 cells/microl, 95% CI 74.7-124.9, p=0.02, and mean percentage 6.0%, 95% CI 4.9-7.1%, p=0.037). In addition, in GBS patients, the number and proportion of CD4+ T cells expressing CD25+ and HLA-DP, DQ, DR (mean number 11.9 cells/microl, 95% CI 7.6-16.1 and mean percentage 0.8%, 95% CI 0.5-1.1%) was lower than in healthy controls (23.5 cells/microl, 95% CI 16.4-30.6, p=0.01, and mean percentage 1.4%, 95% CI 1.1-1.8%, p=0.005. Since CD4+CD25+ cells include cells with special immunoregulatory functions, further investigation of this phenomenon and its relation to possible loss of regulatory T cell function in GBS is warranted.

Increased circulating T cell reactivity to GM1 ganglioside in patients with Guillain–Barré syndrome

This study was performed to determine whether increased ganglioside-specific T cell reactivity can be detected in the peripheral blood of patients with Guillain-Barre syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). T cell responsiveness to the gangliosides GM1, GM3, GD1a, GD1b, GD3, GT1b, GQ1b and sulphatide was assessed in peripheral blood mononuclear cells from untreated GBS patients (57), CIDP patients (43), patients with other peripheral neuropathies (55) and healthy control subjects (74) in a standard 6-day proliferation assay. Increased T cell reactivity to GM1 occurred in GBS patients compared to healthy controls and patients with other neuropathies. There was increased reactivity to GM3 in GBS patients compared to patients with other neuropathies but not compared to healthy controls. The frequencies of increased T cell reactivity to GM1 and GM3 in CIDP patients were intermediate between those of GBS patients and controls. We suggest that T cell reactivity to gangliosides might play a contributory role in the pathogenesis of GBS and perhaps CIDP.

Antiviral reactivities of gammadelta T cells

The complex antiviral immune mechanisms involve both adaptive and innate reactions mediated by γδ T lymphocytes, whose unique immunosurveillance contributions are analyzed here in different clinical and experimental settings. It is beyond any doubt that the fast, potent, cytotoxic as well as non-cytolytic antiviral activities of γδ T cells are critical in protecting the host against diverse viral pathogens.

Gangliosides act as onconeural antigens in paraneoplastic neuropathies

We describe two patients with progressive neuropathy and lung cancer in whom gangliosides (GS) may represent the oncoantigens. Patient 1 had motor neuropathy, high titers of IgG1 and IgG3 to GD1a and GM1, and expansion of circulating gamma-delta T lymphocytes, a T-cell subset responding to glycolipids. Patient 2 presented with Miller-Fisher-like syndrome and IgG3 activity to disialo-GS. In both cases, decreased autoimmune responses and stabilization of neuropathy were accomplished by tumor treatment. By immunohistochemistry, patient 1's IgG bound to his own tumor and to structures of normal nervous system expressing GD1a or GM1. Infiltration of IgG in the same neural structures was found at his autopsy. Regarding cellular immunity, the proportion of gamma-delta T lymphocytes infiltrating carcinoma from patient 1 was significantly higher than in neoplastic controls. These results indicate that GS may represent onconeural antigens in paraneoplastic neuropathy (PNN); their expression on neoplastic tissue may elicit autoimmune responses, which also target neural structures.

Blood ?? T cells,Campylobacter jejuni, and GM1 titers in Guillain-Barr� syndrome

The gammadelta T cells participate in microbial defense, are prevalent in intestinal epithelia, and are activated in autoimmune diseases. We studied whether peripheral blood gammadelta cells and gammadelta subsets are increased in Guillain-Barré syndrome (GBS) and whether elevations are associated with Campylobacter jejuni infection or GM1 elevations. In 20 GBS patients, we performed serial flow cytometry studies of blood gammadelta, Vdelta1, and Vdelta2 cells (+/- CD8+), C jejuni, and ganglioside titers. There was no significant difference in median gammadelta T-cell percentages between GBS patients and controls at onset and at convalescence. However, 5 patients had marked Vdelta1/CD8+ elevations. Elevated Vdelta1 or Vdelta1/CD8+ cells occurred in 3 of 6 patients with C jejuni or GM1 titer elevations. A minority of GBS patients have elevations of Vdelta1/CD8+ cells, possibly associated with elevated C jejuni or GM1 titers. The gammadelta T cells may have a cytotoxic (or suppressor) role in the disease.

CDR3 spectratyping analysis of the T cell receptor repertoire in Guillain-Barré and Fisher syndromes

Several autoimmune and infectious disorders show oligoclonal expansion of particular T cell phenotypes. The extent of T cell involvement in the pathogenesis of Guillain-Barré syndrome (GBS), a post-infectious autoimmune neuropathy, however, is not clear. To identify the pathogenic T cell phenotypes in GBS and Fisher syndrome (FS), variations in T cell receptor use of the V beta 1-24 and V delta 1-5 chain genes were analyzed at complementarity-determining region 3 level in 119 patients with GBS or FS. Overall, V beta and V delta spectratypes were expanded more frequently in patients with GBS (V beta in 77%, V delta in 53%) or FS (V beta in 75%, V delta in 65%) than in the healthy controls (V beta in 59%, V delta in 38%). No particular spectratype was significantly associated with GBS or FS. Subgrouping the patients by Campylobacter jejuni serology and anti-ganglioside IgG antibodies also failed to detect particular spectratype gene use. The frequency of V beta 5.2 expansion tended to be higher in patients with positive Haemophilus influenzae serology (50%) than in the controls (7%), but the difference was not significant. Our findings show that oligoclonal expansion of T cells bearing particular type T cell receptor V beta and V delta genes frequently occurs in GBS and FS, suggestive that T cells mediate the development of these neuropathies. The predominant phenotypes vary, even within subgroups of patients with a syndrome of single etiological origin or those with uniform serological features.

Accumulation of a potent gammadelta T-cell stimulator after deletion of the lytB gene in Escherichia coli

Activation of human Vgamma9/Vdelta2 T cells by many pathogens depends on the presence of small phosphorylated non-peptide compounds derived from the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway of isoprenoid biosynthesis. We here demonstrate that in Escherichia coli mutants deficient in lytB, an essential gene of the MEP pathway, a potent Vgamma9/Vdelta2 T-cell activator accumulates by a factor of approximately 150 compared to wild-type E. coli. The compound responsible for the strong immunogenicity of this E. coli mutant was subsequently characterized and identified as a small pyrophosphorylated metabolite, with a molecular mass of 262 Da, derived from the MEP pathway. Stimulation of human peripheral blood mononuclear cells (PBMC) with extracts prepared from the lytB-deficient E. coli mutant led to upregulation of T-cell activation markers on the surface of Vgamma9/Vdelta2 T cells as well as proliferation and expansion of Vgamma9/Vdelta2 T cells. This response was dependent on costimulatory growth factors, such as interleukin (IL)-2, IL-15 and IL-21. Significant levels of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were secreted in the presence of IL-2 and IL-15, but not in the presence of IL-21, demonstrating that proliferating phosphoantigen-reactive Vgamma9/Vdelta2 T cells do not necessarily produce proinflammatory cytokines.

Structure of gammadelta T cell receptors and their recognition of non-peptide antigens

The gammadelta T cell receptors (TCRs) and alphabeta TCRs are similar in both sequence and structure; however, gammadelta+ and alphabeta+ T cells are not merely similar lymphocytes with subtly different receptors. These cell types differ in several ways, including the types of antigens recognized, the mechanism of antigen presentation and recognition and the mechanism and kinetics of downstream signaling events. gammadelta TCRs can directly recognize antigens in the form of intact proteins or non-peptidic compounds, unlike alphabeta TCRs which recognize peptide antigens bound to major histocompatibility complex molecules (MHC). One of the major classes of human gammadelta+ T cells expresses Vgamma9Vdelta2 TCRs which recognize pyrophosphomonoester, alkylamine and aminobisphosphonate antigens. This review focuses on the recently determined structure of a Vgamma9Vdelta2 TCR, with emphasis on antigen recognition and receptor signaling.

Interferon beta1a treatment modulates TH1 expression in gammadelta + T cells from relapsing-remitting multiple sclerosis patients

A paradigm exists that multiple sclerosis is causally related to dysregulation of TH1 inflammatory cytokines and TH2 antiinflammatory cytokines. The cytokine source(s) that initiate the imbalances are unknown. In this study, gammadelta, CD4, and CD8 T cell receptor-positive (TCR+) cells were isolated from the blood of 26 definitive relapsing-remitting multiple sclerosis patients prior to interferon beta-1a (IFNbeta1a) therapy and following 8-10 weeks of this therapy. The bioactivities of interferon gamma (IFNgamma), interleukin 10 (IL10), and interleukin 12 (IL12) were determined. The concentrations of IFN-gamma, IL10, and IL12 from each cell type did not change significantly with IFNbeta1a treatment. The IL10 secreted by gammadelta TCR+ cells strongly correlated with the IL12 secreted by the same gammadelta TCR+ cells, supporting the paradigm. Furthermore, IFNbeta1a therapy decreased the gammadelta TCR+ cell secretion of TH1 cytokines after 8-10 weeks of therapy.

CD1 expression is differentially regulated by microglia, macrophages and T cells in the central nervous system upon inflammation and demyelination

Expression of CD1 by microglia, macrophages and T cells was investigated ex vivo. In the healthy central nervous system (CNS), resident microglia, macrophages and T cells express levels of CD1 significantly lower than that expressed by splenic macrophages and T cells. During experimental autoimmune encephalomyelitis (EAE), CD1 expression by microglia and the number of CD1+ microglia increase. Macrophages and T cells strongly upregulate CD1 expression in the CNS, but not in the spleen. Whereas the function of CD1 expressed by T cells remains unclear, the expression by microglia and macrophages provides the CNS with a (glyco)lipidic-presenting molecule in an inflammatory and demyelinating environment.

Innate immunity and autoimmunity: from self-protection to self-destruction

Innate immune responses provide the body with its first line of defense against infections. Signals generated by a subset of lymphocytes, including natural killer (NK) cells and natural killer T (NKT) cells, during the early host response might have an additional role in determining the nature of downstream adaptive immune responses. Here, Fu-Dong Shi, Hans-Gustaf Ljunggren and Nora Sarvetnick discuss the role of cellular and soluble components of innate immunity in the development of autoimmune diseases. Some putative pathways leading from innate immunity to autoimmunity are proposed.