Neuromyelitis optica spectrum disorders: comparison of clinical and magnetic resonance imaging characteristics of AQP4-IgG versus MOG-IgG seropositive cases in the Netherlands.

BACKGROUND AND PURPOSE: Neuromyelitis optica spectrum disorders (NMOSDs) are a group of rare inflammatory demyelinating disorders of the central nervous system. The identification of specific antibodies directed to aquaporin 4 (AQP4-IgG) led to the distinction from multiple sclerosis. However, up to 25% of the clinically diagnosed NMO patients are seronegative for AQP4-IgG. A subgroup of these patients might be identified by antibodies directed to myelin oligodendrocyte glycoprotein (MOG-IgG). Our objective was to investigate whether the clinical characteristics of these patients differ. METHODS: Using a cell-based assay, samples of 61 AQP4-IgG seronegative patients and 41 AQP4-IgG seropositive patients with clinically NMOSD were analysed for the presence of MOG-IgG. Clinical characteristics of the AQP4-IgG, MOG-IgG seropositive and double seronegative NMOSD patients were compared. RESULTS: Twenty of the 61 AQP4-IgG seronegative patients tested MOG-IgG seropositive (33%). MOG-IgG seropositive patients were more frequently males in contrast to AQP4-IgG seropositive patients (55% vs. 15%, P < 0.01) and Caucasians (90% vs. 63%, P = 0.03). They more frequently presented with coincident optic neuritis and transverse myelitis (40% vs. 12%, P = 0.02) and had a monophasic disease course (70% vs. 29%, P < 0.01). AQP4-IgG seropositive patients were 2.4 times more likely to suffer from relapses compared with MOG-IgG seropositive patients (relative risk 2.4, 95% confidence interval 1.2-4.7). AQP4-IgG seropositive patients had higher Expanded Disability Status Scale levels at last follow-up (P < 0.01). CONCLUSION: Antibodies directed to MOG identify a subgroup of AQP4-IgG seronegative NMO patients with generally a favourable monophasic disease course.

Bone-marrow transplantation fails to halt intrathecal lymphocyte activation in multiple sclerosis.

BACKGROUND: Given the presumed key role for autoreactive lymphocytes in multiple sclerosis (MS), treatment strategies have been developed to ablate lymphocyte activity. Intrathecal lymphocyte activation can be measured by CSF-soluble(s)CD27. OBJECTIVE: To determine the effect of maximum whole-body immune ablation on two different markers that detect lymphocyte activation in CSF-oligoclonal IgG bands and levels of CSF-sCD27. DESIGN, SETTING AND PATIENTS: The study quantified sCD27 levels and assessed the presence of oligoclonal IgG bands in CSF samples of secondary progressive patients with MS treated by autologous bone-marrow transplantation. In eight individuals, CSF was taken before and 6-9 months after conditioning. CSF-sCD27 levels were compared with other MS and non-inflammatory neurological disease controls. Regarding the effect of stem-cell transplantation on CSF oligoclonal bands, the study analysed pooled data of this and four other international studies on stem-cell transplantation in MS. RESULTS: CSF-sCD27 was significantly lower after the extremely immunoablative protocol. However, levels remained elevated compared with non-inflammatory controls and stayed within the range observed in other MS controls. The joint analysis of CSF oligoclonal bands demonstrated persistence of this immune abnormality in 88% of the reported cases (n = 34). CONCLUSIONS: The persistence of CSF lymphocyte activation markers sCD27 and intrathecal oligoclonal IgG bands after maximum immunoablative treatment indicates that complete eradication of activated lymphocytes from the CNS has not been established. This is paralleled by disease progression observed in several studies on the effect of stem-cell transplantation in MS.

A three-year study of brain atrophy after autologous hematopoietic stem cell transplantation in rapidly evolving secondary progressive multiple sclerosis.

BACKGROUND AND PURPOSE: In multiple sclerosis (MS), autologous hematopoietic stem cell transplantation (AHSCT) induces a profound suppression of clinical activity and MR imaging-detectable inflammation, but it may be associated with a rapid brain volume loss in the months subsequent to treatment. The aim of this study was to assess how AHSCT affects medium-term evolution of brain atrophy in MS. MATERIALS AND METHODS: MR imaging scans of the brain from 14 patients with rapidly evolving secondary-progressive MS obtained 3 months before and every year after AHSCT for 3 years were analyzed. Baseline normalized brain volumes and longitudinal percentage of brain volume changes (PBVCs) were assessed using the Structural Image Evaluation of Normalized Atrophy software. RESULTS: The median decrease of brain volume was 1.92% over the first year after AHSCT and then declined to 1.35% at the second year and to 0.69% at the third year. The number of enhancing lesions seen on the pretreatment scans was significantly correlated with the PBVCs between baseline and month 12 (r = -0.62; P = .02); no correlation was found with the PBVCs measured over the second and third years. CONCLUSIONS: After AHSCT, the rate of brain tissue loss in patients with MS declines dramatically after the first 2 years. The initial rapid development of brain atrophy may be a late consequence of the pretransplant disease activity and/or a transient result of the intense immunoablative conditioning procedure.

Resetting the adaptive immune system after autologous stem cell transplantation: lessons from responses to vaccines.

Autologous stem cell transplantation (ASCT) to treat autoimmune diseases (AID) is thought to reset immunological memory directed against autoantigens. This hypothesis can only be studied indirectly because the exact nature of the pathogenetic autoantigens is unknown in most AID. Therefore, 19 children with juvenile idiopathic arthritis (JIA) or systemic lupus erythematodes (SLE) and 10 adults with multiple sclerosis (MS) were vaccinated with the T-cell-dependent neoantigen rabies and the recall antigen tetanus toxoid after, respectively before, bone marrow harvest. Both vaccinations were repeated after ASCT. All except two of the responders mounted a primary antibody response to rabies after revaccination, and 44% of the responders mounted a primary antibody response to tetanus boost after ASCT. These data show that immunological memory to a neoantigen is lost in most patients with AID after immunoablative pretreatment; however, memory to a recall antigen boosted before bone marrow harvest is only lost in part of the patients. Disease progression was arrested in all patients with JIA/SLE except one, but only in a minority of MS patients. Clinical outcome on a per case basis was not associated with the profile of the immune response toward the vaccination antigens after ASCT.

T-lymphocyte reconstitution following rigorously T-cell-depleted versus unmodified autologous stem cell transplants.

We compared the kinetics of T-cell recovery after extensive ex vivo and in vivo T-cell depleted autologous stem cell transplantation (SCT) for multiple sclerosis (MS; n=8) with unmodified SCT for hematological malignancies (HM; n=39). Both patient group showed a very protracted recovery of 'naive' CD4(+), 45R0(-) ( approximately CD45RA(+)) T-cells. Within the 'primed' CD4(+), 45R0(+) T-cells, the 'central memory' cells expressing the CD62L and CD27 markers were the slowest to recover. The repopulating T-cells were highly activated, as shown by increased expression of HLA-DR and the apoptosis marker CD95. The capability of CD4(+) and CD8(+) T-cells to produce IFN-gamma, IL-2 and TNF-alpha had reached normal ranges from 2 months post SCT onwards. Unexpectedly, the kinetics of T-cell recovery between 3 and 12 months post transplant was similar in T-depleted and unmodified SCT. Before SCT, the HM patients showed lymphopenia of all T-cell subsets, upregulated HLA-DR and CD95 expression and increased cytokine responses. We suggest that the similar kinetics of T-cell recovery in the two patient groups may be explained by the susceptibility to apoptosis of the activated CD4(+) T-cells in the autografts of the HM patients. This susceptibility to apoptosis would interfere with a swift and sustained CD4(+) T-cell regeneration post SCT.

Intense T cell depletion followed by autologous bone marrow transplantation for severe multiple sclerosis.

BACKGROUND: Certain stem cell transplantation procedures might slow down inflammatory pathology in multiple sclerosis (MS). AIMS: To halt disease progression in aggressive MS by a bone marrow transplantation (BMT) protocol aimed at maximum T cell suppression. METHODS: Autologous BMT was performed in 14 patients with rapid secondary progressive MS (median EDSS score at baseline, 6; median disease duration, five years). To accomplish rigorous T cell ablation, a strong conditioning protocol was chosen--cyclophosphamide, total body irradiation, and antithymocyte globulin. To minimise the possibility of reinfusing mature T cells in the graft, bone marrow, not peripheral blood, was used as the CD34+ stem cell source. RESULTS: Median follow up was 36 months (range, 7-36). Post-transplant haemopoietic recovery was successful in all patients. Early toxicity included Epstein-Barr virus related post-transplantation lymphoproliferative disorder. Longterm effects were development of antithyroid antibodies (three) and myelodysplastic syndrome (one). One patient died of progressive disease five years after transplantation. Treatment failure, defined by EDSS increase sustained for six months or more, was seen in nine patients and stabilisation or improvement in five. Other clinical parameters generally showed the same outcome. No gadolinium enhanced lesions were seen on post-treatment magnetic resonance imaging, in either cerebral or spinal cord scans. However, cerebrospinal fluid oligoclonal bands remained positive in most cases. CONCLUSIONS: This strong immunosuppressive regimen did not prevent clinical progression in patients with aggressive secondary MS. The lack of efficacy, together with some serious side effects, does not favour the use of similar rigorous T cell depleting protocols in the future.

Epstein-Barr virus and disease activity in multiple sclerosis.

OBJECTIVES: To study in relapsing-remitting (RR) multiple sclerosis (MS) whether exacerbations and brain activity as measured by magnetic resonance imaging (MRI) are associated with plasma levels of anti-Epstein Barr (EBV) antibodies and EBV DNA. METHODS: This was a prospective study with 73 RR MS patients followed for an average of 1.7 years with frequent neurological examination and blood sampling. Antibodies to various EBV proteins were measured by ELISA and plasma EBV DNA was measured by PCR. RESULTS: All MS patients had IgG antibodies to EBV (viral capsid antigen (VCA) and/or EBV nuclear antigen (EBNA)), irrespective whether samples were taken at stable disease or exacerbation. A significantly elevated percentage of the patients (48%) had antibodies against EBV antigens (early antigen, EA) that indicate active viral replication, compared with the age matched healthy controls (25%). Antibodies against a control herpesvirus, cytomegalovirus, were similar between the two groups. The percentage of EA positive individuals and EA titres did not differ between stable disease or exacerbation. Anti-VCA IgM was positive in three cases, unrelated to disease activity. Using a highly sensitive PCR on 51 samples taken at exacerbation visits, only three patients were found to have one timepoint with viraemia, and this viraemia was unrelated to disease activity. Of special note was the fact that anti-EA seropositive patients remained seropositive during follow up, with stable titres over time. We hypothesised that these patients may constitute a subgroup with higher disease activity, due to the triggering effect of a chronic attempt of the virus to reactivate. The EA positive group did not differ from the EA negative with respect to clinical disease activity or other characteristics. However, in the EA positive group, analysis with gadolinium enhanced MRI indicated more MRI disease activity. CONCLUSIONS: There was no evidence for increased clinical disease activity in the subgroup of MS patients with serological signs of EBV reactivation. However, the observation that chronic EBV reactivation may be associated with increased inflammatory activity as assessed by gadolinium enhanced MRI lesions should be reproduced in a larger and independent dataset.

Difference in distribution of muscle weakness between myasthenia gravis and the Lambert-Eaton myasthenic syndrome.

BACKGROUND: Myasthenia gravis and the Lambert-Eaton myasthenic syndrome (LEMS) may have a similar distribution of muscle weakness. Deciding on a diagnosis of myasthenia gravis or LEMS on clinical grounds may therefore be difficult. OBJECTIVE: To compare the localisation of initial muscle weakness and the distribution of weakness at the time of maximum severity in patients with myasthenia gravis and LEMS. SUBJECTS: 101 patients with myasthenia gravis and 38 patients with LEMS. RESULTS: In myasthenia gravis, initial weakness involved extraocular muscles in 59%, bulbar muscles in 29%, and limb muscles in 12% of the patients. In LEMS no patient had ocular weakness, 5% had bulbar weakness, and 95% had weakness of the limbs as the first symptom (p < 0.001). At the point of maximum severity, weakness in myasthenia gravis was purely ocular in 25%, oculobulbar in 5%, restricted to the limbs in 2%, and present in both oculobulbar muscles and limbs in 68%. At this point, none of the LEMS patients had weakness restricted to extraocular or bulbar muscles (p = 0.002). The legs were affected in all LEMS patients, whereas in 12 patients with generalised myasthenia gravis limb weakness was restricted to the arms (p = 0.024). CONCLUSIONS: In a patient suspected to have a myasthenic syndrome whose first symptom is ocular weakness, LEMS is virtually excluded. Limb weakness confined to the arms is only found in generalised myasthenia gravis and not in LEMS. Muscle weakness in myasthenia gravis tends to develop in a craniocaudal direction, and in the opposite direction in LEMS.

Stem cell transplantation in multiple sclerosis: multiple choices and multiple challenges.

Multiple sclerosis (MS) is generally considered as an autoimmune disease of the central nervous system. This concept has led to the idea that profound immunosuppression followed by transplantation of stem cell grafts would stop, or at least slow down, disease activity. Supported by the positive effects of hematopoietic stem cell transplantation (HSCT) on experimental autoimmune encephalomyelitis and by anecdotal reports on the beneficial effect of HSCT on MS patients with concomitant malignant disease, HSCT programs for MS have been initiated worldwide. At this stage, it is impossible to draw general conclusions from the preliminary data reported and therefore overenthusiastic expectations should be tempered. The follow-up periods are too short the groups are too small, the selected patients and protocols too heterogeneous, and publication bias on positive results cannot be excluded. However, there is ample evidence that HSCT is a technically feasible approach in MS, not more dangerous than in the hemato-oncological diseases. For every step in the HSCT procedure, there are many different options. The time has come for a systematic analysis of the safety and efficacy associated with the different methodologies.

Glioblastoma causing granulocytosis by secretion of granulocyte-colony-stimulating factor.

We describe a patient with a glioblastoma multiforme with excessive granulocytosis in the peripheral blood. Shown at both protein and mRNA levels, the tumor produced very high levels of granulocyte-colony-stimulating factor (G-CSF). G-CSF is a growth factor that induces the recruitment of granulocytes. The paraneoplastic phenomenon described here partly mimicked a brain abscess. Production of G-CSF by (brain) tumor cells might be related to the granulocytosis common in malignant disease.

Interferon (IFN)-beta treatment enhances CD95 and interleukin 10 expression but reduces interferon-gamma producing T cells in MS patients.

Interferon (IFN)-beta has been shown to favorably alter the disease course of relapsing-remitting multiple sclerosis (RRMS) patients. Although its mode of action is still unclear, there is ample evidence from in vitro studies that IFN-beta directly modulates the function of immune cells. We analyzed here the effects of IFN-beta treatment on immune functions in vivo in a group of 25 RRMS patients who received IFN-beta (8 MIU) on alternate days. At baseline and at 1, 3 and 6 months from the start of the treatment, parameters for differentiation and activation states of both monocytes and T lymphocytes were assessed. A transient increase was seen in plasma (p) interleukin (IL)-10 level whereas pIL-12 (p40) was not affected. A similar change was found in the ability of monocytes to secrete these cytokines in vitro. Notably, patients who in vitro readily responded to IFN-beta with enhanced IL-10 production had the highest pIL-10 levels. Concerning T-cell differentiation, flow cytometric analysis of cytokine production showed that treatment with IFN-beta moderately decreased the mean percentages of CD8pos T cells producing IL-2 and IFN-gamma and CD8neg T cells producing IL-4 (p<0.05 for all cytokines), whereas a more significant decline was seen in the mean percentage of CD8neg T cells producing IFN-gamma (p<0.01). This resulted in a significant lower ratio T(HELPER(H))1 vs. T(HELPER(H))2 type cells in the CD8pos T-cell subset (p<0.05), but not in the CD8neg T-cell subset. Finally, IFN-beta treatment resulted in an initial rise in the mean percentage of CD95pos T cells and in a gradual increase in the mean level of soluble CD95 (sCD95) in plasma (p<0.01). Additional in vitro studies showed that IFN-beta indeed rapidly (within 24 h) upregulates CD95 expression on both primed and unprimed T cells and augments the release of sCD95 in culture supernatants. Thus, we confirm here that IFN-beta treatment leads to similar changes in cytokine production of T cells and monocytes as previously described in vitro. Enhanced IL-10 secretion may downmodulate cytokine secretion by activated T cells and in this way dampen newly-induced and/or ongoing immune responses. In addition, we identified a novel effect of IFN-beta treatment, i.e., induction of CD95 expression. The augmentation of CD95 expression may directly interfere with T-cell selection, notably of autoaggressive T cells. Future studies are needed to show whether this increased CD95 expression indeed leads to increased apoptosis of immune cells.

Cerebrospinal fluid concentrations of soluble CD27 in HTLV-I associated myelopathy and multiple sclerosis.

OBJECTIVES: Stimulation of T lymphocytes via the T cell receptor strongly enhances CD27 membrane expression and induces the release of a soluble 32 kDa form of CD27 (sCD27). CD27 is a member of the TNF receptor family, a group of molecules that have important roles in lymphocyte differentiation and survival. Raised concentrations of sCD27 have been reported in various immunopathological conditions and there is evidence that this molecule can serve as a marker of T cell activation in vivo. Concentrations of sCD27 in CSF were compared between patients with T cell mediated neurological disease and non-inflammatory controls. Also, the relation of CSF-sCD27 concentrations with clinical disease activity was investigated in patients with multiple sclerosis. METHODS: Four groups were studied: (1) eight patients with HTLV-1 associated myelopathy/ tropical spastic paraparisis (HAM)/TSP), (2) eight HTLV-I carriers, (3) 41 patients with multiple sclerosis, and (4) 43 patients with other neurological disease (OND). Concentrations of CSF-sCD27 were determined by enzyme linked immunosorbent assay (ELISA). RESULTS: Quantification of CSF-sCD27 differentiates patients with HAM/TSP from HTLV-I carriers (p<0.01) and from patients with OND (p<0.001). Moreover, the multiple sclerosis patient group was different from the OND group (p<0.0001). In patients with multiple sclerosis, CSF-sCD27 concentrations were higher in 24 patients with clinically active disease than in 17 with clinically stable disease. In addition, most of the patients with multiple sclerosis with high sCD27 concentrations showed an increase in EDSS, whereas none of the patients with low sCD27 had an EDSS increase. CONCLUSIONS: As a reliable marker of immunological disease activity in inflammatory white matter disease is still not available, it is proposed that quantification of CSF-sCD27 concentrations is a good candidate. Also, it may serve as a tool to stratify neurological diseases in inflammatory and non-inflammatory states.

Expression of the activation antigen CD27 in rheumatoid arthritis.

Differentiation of CD4+ T-cells is reflected by the change from the CD45RA+CD27+ phenotype via CD45RO+CD27+ to the CD45RO+CD27- phenotype. To provide insight into the migration and activation of T-cells at the site of inflammation in rheumatoid arthritis (RA), CD27 expression by T-cells in peripheral blood (PB), synovial fluid (SF), and synovial tissue (ST) as well as the levels of the soluble form of CD27 (sCD27) in plasma and SF were studied in patients with RA. Since CD4+CD27+ T-cells are involved in providing helper activity for B-cells, we also investigated the levels of rheumatoid factors in serum and SF in relation to CD27 expression. The mean level of sCD27, which is produced by CD27+ cells, and the mean percentage of CD27 T-cells within the CD4+CD45RA- subset were higher in SF than in PB. SF sCD27 levels were higher in the patients with RA than in the patients with osteoarthritis, who served as controls. In ST infiltration by CD4+CD45RO+CD27+ T-cells, could be demonstrated in the rheumatoid perivascular lymphocytic aggregates with a relative increase in the percentage of CD27- T-cells in the diffuse lymphocytic infiltrate. The sCD27 levels and the percentages of CD4+CD27+ cells in SF correlated positively with the levels of rheumatoid factors in serum and SF. The findings presented in this study suggest a continuous influx of preactivated CD4+CD45RO+CD27+ cells from the PB into the rheumatoid ST and further activation and differentiation to CD4+CD45RO+CD27- cells in situ, followed by migration to the SF. These activated T-cells are likely to play a role in synovial inflammation.

Recombinant interferon-beta blocks proliferation but enhances interleukin-10 secretion by activated human T-cells.

Results from recent clinical trials have indicated that recombinant interferon-beta (rIFN-beta) is a promising drug for the treatment of Multiple Sclerosis (MS), a disease of supposed autoimmune etiology. To gain insight into the immunoregulatory properties of this cytokine, we analyzed effects of interferon-beta (IFN-beta) on T-cell functions in vitro. Interferon-beta inhibited T-cell proliferation, as well as T-cell-dependent immunoglobulin secretion, in a dose-dependent manner. IFN-beta did not inhibit upregulations of CD40L on activated T-cells, but blocked induction of CD25 on stimulated T- and B-lymphocytes. Secretion of interferon-gamma (IFN-gamma), tumour necrosis alpha (TNF-alpha) and IL-13 was inhibited by the addition of IFN-beta, whereas IL-4 secretion was unaffected. Interestingly, IFN-beta enhanced secretion of IL-2 about two-fold and secretion of IL-10 nearly four-fold. In summary, these findings suggest that IFN-beta may exert direct effects on T- and beta-cell function in vivo. In addition, enhanced secretion of IL-10 by activated T-cells may interfere with newly initiated and ongoing inflammatory immune reactions.

Elevation of cerebrospinal fluid soluble CD27 levels in patients with meningeal localization of lymphoid malignancies.

Diagnosis of meningeal localization of lymphoid malignancies by means of cytologic examination of the cerebrospinal fluid (CSF) can be difficult. Thus far no reliable CSF tumor markers have been identified. CD27 is a transmembrane disulfide-linked 55-kD homodimer present on most peripheral blood T cells and on a subset of B cells. CD27 is also expressed on human malignant B cells and high levels of soluble CD27 can be present in the serum of patients with B-cell malignancies. The aim of this study is to determine prospectively the diagnostic value of CSF sCD27 as a tumor marker in patients with meningeal localization of lymphoid malignancies. CSF sCD27 levels were determined by sandwich enzyme-linked immunosorbent assay. The optimal cut-off value using receiver operator characteristics curves was found to be 10 U/mL. sCD27 levels were normal in all 50 control patients (lumbar disc protrusion) and in 39 of 40 samples obtained from patients with either solid tumors or acute myeloid leukemia. Of 104 CSF samples from 70 children with acute lymphoblastic leukemia (ALL) or non-Hodgkin's lymphoma (NHL) undergoing routine central nervous system (CNS) staging, sCD27 was false positive and false negative in only one sample each. In 70 samples from 45 patients suspected of meningeal localization of ALL or NHL, the sCD27 test had an excellent sensitivity (100%) and specificity (82%). In 7 patients with positive CSF studied longitudinally, sCD27 levels correlated very well with remission and relapse. sCD27 levels were not nonspecifically increased by the administration of cytostatic drugs. Finally, sCD27 was also elevated in the 4 patients studied with primary central nervous system lymphoma (PCNSL). CSF sCD27 is a promising tumor marker in patients with either meningeal localization of lymphoid malignancies or PCNSL, and can be useful in the differential diagnosis of CNS involvement by either lymphoid malignancies or solid tumors.

CD27-CD70 interaction: unravelling its implication in normal and neoplastic B-cell growth.

Members of the Tumour Necrosis Factor-Receptor (TNFR) family play an essential role in the control of lymphoid cell growth and differentiation. The ligand of one of its lymphoid-specific members, CD27, was recently characterized as CD70, a type II transmembrane molecule with homology to TNF that is expressed on activated T and B cells. Ligation of CD27 by its natural ligand generates a potent costimulatory signal for cytokine production and proliferation of activated T cells. In contrast to normal B cells, where CD27 expression is confined to germinal centre cells and to a small subset of circulating B lymphocytes, CD27 expression is found on a large array of distinct B-cell neoplasia. Here, we review recent data on the expression and function of TNFR family members on normal and malignant lymphocytes and propose a role for CD27-CD70 interaction in B-cell development.

Serum levels of soluble forms of T cell activation antigens CD27 and CD25 in systemic lupus erythematosus in relation with lymphocytes count and disease course.

Systemic lupus erythematosus (SLE) patients are characterized by a low lymphocyte count, which is considered a specific disease marker and is related to disease activity. The membrane bound molecules CD25 and CD27 are expressed and released in a soluble CD25 (sCD25) and soluble CD27 (sCD27) form by activation of predominantly T cells. In previous studies it was claimed that sCD25 as well sCD27 might be used as parameters for activation of the immune system; a correlation between the sCD25 profile with the disease course in SLE patients was also shown. To assess the relationship between lymphocyte count and these T cell activation markers, we performed a cross-sectional and a longitudinal study. In the longitudinal study three SLE patients who were known for a long time at our outpatient clinic were studied. Both T cell markers strongly correlated with each other and formed a reflection of the disease course. In all 7 periods of exacerbation, which we observed in the 3 investigated patients, both levels increased preceding this period; however, no correlation was found with the lymphocyte count. In the cross sectional study of 69 patients with SLE, sCD25 and sCD27 levels were correlated with defined disease manifestations; sCD25 was elevated in all periods of increased disease activity. The same holds true for sCD27, with the exception of patients with nephritis in which the highest levels were observed. Both profiles of sCD25 and sCD27 were strongly correlated during the whole disease course. Our data prove that in the pathogenesis of SLE an active recruitement of unprimed and primed T cells takes place.

Engagement of CD27 with its ligand CD70 provides a second signal for T cell activation.

Molecules of the TNF-R family have been shown to be essential in the regulation of lymphocyte growth and differentiation. The TNF-R family member CD27 binds to a type II transmembrane molecule belonging to the TNF gene family (CD27L) that is identical to the lymphocyte activation Ag CD70. Using transfected mouse fibroblasts expressing human CD70, we demonstrate here that interaction of CD27 with its ligand provides a potent second signal for cytokine production, induction of activation Ags, and proliferation of unprimed CD45RA+, and to a lesser extent, of primed CD45R0+ peripheral blood T cells. In contrast to costimulatory signals delivered via the CD28-ligand B7-1 (CD80), CD70 was found to induce relatively low IL-2, IL-4, and IL-10 but comparable TNF-alpha secretion. Proliferation of CD45RA+, but not of CD45R0+ T cells, was found to be largely resistant to blocking of IL-2/IL-2R interaction. Finally, the finding that CD70 and CD80 cooperate in the induction of T cell proliferation indicates that cooperation of both molecules may be essential for optimal T cell stimulation. The interaction between CD27 and its ligand CD70 might be of particular importance for the recruitment of T cells from the unprimed T cell pool. Moreover, as CD70 expression in vivo is confined to activated B and T lymphocytes, only a limited set of APC are able to generate this specific second signal for T cell expansion.

Analysis of CD27 surface expression on T cell subsets in MS patients and control individuals.

Within the peripheral blood, CD4+CD27- T cells only reside within the CD45RA- (memory or primed) T cell subset. Cells with this phenotype have characteristics of specialized effector T cells according to their cytokine secretion profiles and the expression of tissue-specific adhesion molecules. This subset was previously found to be increased in certain diseases that are associated with immune activation. Therefore we analyzed CD27 expression of peripheral blood and CSF T cells in MS patients. Within the CD4+ T cell subset no differences were seen between MS patients and controls in proportions of CD45RA-CD27- cells. However, when the CD3+ T cell compartment was analyzed, CD27- cells were also found within the CD45RA+ subset. These cells, most likely CD8+, are significantly reduced in PBL and CSF of MS patients as compared with OND patients. In MS and OND groups the level of CD27- cells in peripheral blood correlated significantly with that in CSF, indicating a balanced migration of CD27- cells between the two compartments. In OIND patients, however, this equilibrium was lost. The correlation of the level of CD27+ cells with the amount of intrathecally produced IgG in MS patients may suggest that CD27+ cells are responsible for B cell help in this disease.