Immunophenotypic patterns of T-cell activation in neuroinflammatory diseases

OBJECTIVES

We aimed to gain insights into the pathogen-specific differences in early adaptive immune responses following central nervous system infections with Borrelia burgdorferi and viral pathogens by studying the immunophenotypic patterns of T-cell activation. Moreover, we wished to determine whether the expression of T-cell activation markers reflects disease activity in multiple sclerosis (MS).

METHODS

Proportions of cerebrospinal fluid T-cells expressing the markers HLA-DR, CD25 and CD38 were determined in patients with MS (n = 40), acute viral meningomyeloradiculoneuritis (VID, n = 26), early neuroborreliosis (NB, n = 23) and non-inflammatory neurologic diseases (n = 51) by using flow cytometry. In relapsing-remitting MS, disease activity was assessed by clinical examination and magnetic resonance imaging.

RESULTS

For each of the surface markers that were examined, significant differences in T cell proportions were found between patient groups. The proportion of HLA-DR+ T cells was higher and that of CD25+ T cells lower in NB compared with VID. These differences were attributable only to the early phase of the disease (< or = 6 days after symptom onset). Among MS patients, there was a trend for higher proportions of T cells expressing activation markers in patients with gadolinium-enhancing lesions.

CONCLUSIONS

The decreased CD25 expression in NB may reflect immunomodulatory effects of B. burgdorferi facilitating persistent infection. Larger prospective studies of T-cell activation markers for ascertaining the association between cellular markers and clinical surrogates of disease activity in MS are warranted.

Systemic T-cell activation in acute clinically isolated optic neuritis

We examined untreated 60 patients with acute monosymptomatic optic neuritis (ON). Patients examined early after onset showed increased expression of HLA-DR and CD45R0 on CD4 and CD8 T cells. Expression of HLA-DR on CD4 T cells was higher in patients without IgG oligoclonal bands. Expression of HLA-DR on CD4 and CD8 T cells correlated negatively with measures of disease activity and positively with measures of good visual function, and expression of CD45R0 on CD4 T cells correlated negatively with measures of disease activity. We hypothesize that HLA-DR expression may characterize a protective T-cell subset in ON.

[Immune events in central nervous system of early and late onset Alzheimer's disease patients]

INTRODUCTION

Alzheimer s disease (AD) is a progressive degenerative disease affecting a significant proportion of the elderly population. The disease is characterized clinically by a progressive loss of memory function and mental impairment associated with the presence of degenerative well known pathological lesions. Although, the pathogenesis of AD is unclear; several reports indicate the involvement of immune factors.

PATIENTS AND METHODS

This paper evaluates some cerebrospinal fluid immune markers from 21 patients with early and late AD and 20 age matched non-demented subjects. The analytical method included the evaluation of T cell subpopulations (using AcMc CD2, CD4, CD8) and activated T cells (AcMc HLA-DR and CD25) from CSF and peripheral blood by immunocytochemical techniques on a fixed cell slide as described by Bernd. The lymphocyte phenotype expressed as a percentage of positively stained cells for each cell surface marker evaluated.

RESULTS

Some significant differences were observed for T cell subpopulations from different compartments, between the different AD groups and the controls (p< 0.05). Nevertheless, the most significant differences were found in the activated T cells from cerebrospinal fluid between AD groups and controls (p< 0.01).

CONCLUSIONS

These results support the theory of neuroimmune dysregulation, probably involved in the progressive neurodegeneration and dementia in some AD.

Two subsets of dendritic cells are present in human cerebrospinal fluid

Little is known about the presence of dendritic cells in the human CNS. To investigate the occurrence of dendritic cells in the CSF, paired blood/CSF samples from patients with multiple sclerosis, acute optic neuritis, Lyme neuroborreliosis, other inflammatory neurological diseases and non-inflammatory neurological diseases were examined using flow cytometry. Almost all CSF samples contained myeloid (lin-CD11c+HLA-DR++CD123(dim)) and plasmacytoid (lin-CD11c-HLA-DR+CD123(high)) dendritic cells. In non-inflammatory neurological diseases, dendritic cells of either subset only constituted up to 1% of CSF mononuclear cells. Myeloid CSF dendritic cells were elevated in optic neuritis, neuroborreliosis and other inflammatory neurological disorders, while plasmacytoid dendritic cells were elevated in all neuroinflammatory conditions studied, with especially high numbers in neuroborreliosis. Numbers of CSF dendritic cells correlated with the common parameters of CNS inflammation. The myeloid dendritic cells in CSF expressed higher levels of HLA-DR, CD86, CD80 and CD40 than those in blood, whereas expression of these molecules by plasmacytoid dendritic cells was equal in blood and CSF. Both CSF and blood dendritic cells expressed the chemokine receptor CCR5. This is the first demonstration that dendritic cells are present in human CSF and that plasmacytoid dendritic cells are present in a non-lymphoid compartment. Myeloid and plasmacytoid dendritic cells in CSF may contribute to orchestration of the local immune responses.

Quantitation of soluble HLA-DR antigens in human serum and other body fluids

The existence of soluble forms of MHC class II molecules is well established. To quantify soluble HLA-DR antigens (sHLA-DR) in human serum and other body fluids, we developed an enzyme immunoassay using two non-overlapping HLA-DR-specific monoclonal antibodies (RoDR, BL-la/5) and an immunoaffinity chromatography-purified sHLA-DR standard. In serum of healthy individuals, sHLA-DR levels were found in the range between 0.6 and 3 ng/ml (median 0.85 ng/ml) whereas EDTA plasma samples showed concentrations about 20 times higher (median 21 ng/ml). In tears, saliva, sweat, urine, amniotic fluid, cerebrospinal fluid, and bronchoalveolar lavage, sHLA-DR could also be detected. No association was found between sHLA-DR serum levels and distinct HLA specificities. In the sera of patients with autoimmune diseases, slightly enhanced sHLA-DR values were found (juvenile rheumatoid arthritis: median 2.0 ng/ml, lupus erythematosus: 1.5 ng/ml, diabetes mellitus: 2.1 ng/ml).

T cell subsets in peripheral blood and cerebrospinal fluid from children with aseptic meningitis

T cell subsets in peripheral blood (PB) and cerebrospinal fluid (CSF) obtained from patients with aseptic meningitis were studied using quantitative two-color fluorescence analysis with a flow cytometer. The percentage of HLA-DR+/CD3+ lymphocytes (activated T cells) in CSF was significantly increased in the recovery phase when compared to the acute phase, while no significant change in the activated T cells in PB was observed. More interestingly, CD4+ T lymphocytes in CSF were increased in the acute phase and subsequently decreased in the recovery phase. Instead, CD8+ T lymphocytes gradually accumulated into the CSF in the recovery phase, resulting in a successive decrease in the CD4/CD8 ratio. On the other hand, the CD4/CD8 ratio in PB remained normal during the course of aseptic meningitis. The present results suggest that T lymphocytes (CD4+ subset in the acute phase and CD8+ in the recovery phase) could be infiltrated and further activated at the site of inflammation, possibly in the subarachnoid space in the patients with aseptic meningitis.

Parkinson's disease and immunological abnormalities: increase of HLA-DR expression on monocytes in cerebrospinal fluid and of CD45RO+ T cells in peripheral blood

The etiology of Parkinson's disease is mainly unknown. Immune abnormalities have been described, but the cause of such abnormalities has not been resolved. We examined by two-colour flow cytometry HLA-DR antigen expression on monocytes from cerebrospinal fluid (CSF) and blood and, moreover, lymphocyte subpopulations (CD4+ CD45RO+, CD4+ CD45RA+, CD8+ CD11b+high) in peripheral blood from patients with Parkinson's disease compared with age-matched patients with other neurological diseases (OND) and tension headache. We found higher HLA-DR expression on CSF monocytes compared with blood monocytes. This difference was restricted to Parkinson's disease patients. T helper cell analysis revealed a decreased percentage of CD45RA+ "naive" and an increased percentage of CD45RO+ "memory" T cell subset from CD4+ T cells in peripheral blood of patients with Parkinson's disease compared with patients with tension headache. The proportions of CD8+ CD11b+high "suppressor" T cells remained unchanged, among the three patient groups compared. A selective loss of CD4+ CD45RA+ cells, previously observed in diseases like multiple sclerosis and Down's syndrome as compared with healthy controls suggests a common immunological abnormality in neurological disorders.

Increased frequency of interleukin 2-responsive T cells specific for myelin basic protein and proteolipid protein in peripheral blood and cerebrospinal fluid of patients with multiple sclerosis

Equal numbers of CD4+ T cells recognizing myelin basic protein (MBP) and proteolipid protein (PLP) are found in the circulation of normal individuals and multiple sclerosis (MS) patients. We hypothesized that if myelin-reactive T cells are critical for the pathogenesis of MS, they would exist in a different state of activation as compared with myelin-reactive T cells cloned from the blood of normal individuals. This was investigated in a total of 62 subjects with definitive MS. While there were no differences in the frequencies of MBP- and PLP-reactive T cells after primary antigen stimulation, the frequency of MBP or PLP but not tetanus toxoid-reactive T cells generated after primary recombinant interleukin (rIL-2) stimulation was significantly higher in MS patients as compared with control individuals. Primary rIL-2-stimulated MBP-reactive T cell lines were CD4+ and recognized MBP epitopes 84-102 and 143-168 similar to MBP-reactive T cell lines generated with primary MBP stimulation. In the cerebrospinal fluid (CSF) of MS patients, MBP-reactive T cells generated with primary rIL-2 stimulation accounted for 7% of the IL-2-responsive cells, greater than 10-fold higher than paired blood samples, and these T cells also selectively recognized MBP peptides 84-102 and 143-168. In striking contrast, MBP-reactive T cells were not detected in CSF obtained from patients with other neurologic diseases. These results provide definitive in vitro evidence of an absolute difference in the activation state of myelin-reactive T cells in the central nervous system of patients with MS and provide evidence of a pathogenic role of autoreactive T cells in the disease.

Natural killer cells and lymphocyte subsets in active MS and acute inflammation of the CNS

Cerebrospinal fluid (CSF) and peripheral blood (PB) lymphocyte subsets were determined by flow cytometry (FCM) in 15 patients with active multiple sclerosis (MS) and 15 patients with acute inflammatory diseases (ID) of the central nervous system (CNS) in order to establish correlations between the two groups of diseases, as well as between the CSF and PB subsets distribution. A panel of monoclonal antibodies was applied to all the samples: Leu3 (CD4), Leu4 (CD3), Leu2 (CD8), Anti-HLA-DR, Leu11 (CD16). Statistical analysis did not show differences in CD3+ nor in CD3+ DR+ T-cells both in the CSF and PB in the two groups of patients. CD4+ cells were significantly higher in the CSF than in the PB, while CD8+, DR+ CD3- and CD16+ cells were constantly lower in the CSF without differences between the two groups of diseases.

HLA-DR antigen expression on T cells from cerebrospinal fluid in multiple sclerosis and aseptic meningo-encephalitis

HLA-DR expression on T lymphocytes in cerebrospinal fluid (CSF) from patients with multiple sclerosis (MS) and acute aseptic meningo-encephalitis (AM), and from blood only from healthy controls was examined by a new double-immunofluorescence labelling assay using species-specific second layers on prefixed cell samples. Thirteen of 16 patients with AM (81%) had an elevated percentage of DR positive T cells in CSF against only two of 20 patients with MS (10%). Our data indicate that AM, an acute infection of the central nervous system (CNS), is accompanied by accumulation in CSF of activated, DR positive T cells as a reflection of actively involved cellular immunity within the CNS, while this accumulation of DR positive T cells is not seen in MS, a chronic inflammatory CNS disease, despite some of the patients being examined during clinical exacerbations.

IL-2 receptor and HLA class II antigens on cerebrospinal fluid cells of patients with multiple sclerosis and other neurological diseases

The presence of IL-2 receptor and HLA class II antigens as detected by monoclonal antibodies on mononuclear cells from both cerebro-spinal fluid (CSF) and peripheral blood was examined by cytofluorographic analysis in patients with multiple sclerosis (MS) and other neurological diseases. CSF as compared to blood was enriched in cells expressing IL-2 receptor and HLA class II molecules both in MS patients and in other inflammatory diseases of the central nervous system suggesting that activated T-cells concentrate within the central nervous system.