Th1 shift in CIDP versus Th2 shift in vasculitic neuropathy in CSF

To investigate the intra- and extracellular levels of various cytokines and chemokines in CSF in chronic inflammatory demyelinating polyneuropathy (CIDP) and vasculitic neuropathy (VN), 16 cytokines, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 (p70), IL-13, IL-17, IFN-gamma, TNF-alpha, G-CSF, MCP-1 and MIP-1beta, were measured in CSF supernatant by a multiplexed fluorescent bead-based immunoassay and intracellular production of IFN-gamma and IL-4 in CSF CD4+ T cells were simultaneously measured by flow cytometry in 14 patients with CIDP, 8 patients with VN and 25 patients with other noninflammatory neurologic diseases (OND). In the CSF supernatant, a significant increase of IL-17, IL-8 and IL-6, and a significant decrease of IL-4, IL-5 and IL-7 levels were detected in pretreated CIDP as compared with OND. A significant increase of IL-6, IL-8 and IL-10 levels was found in pretreated VN. Both IL-17 and IL-8 levels correlated strongly with CSF protein levels in CIDP, although the correlation of IL-6 levels was weak. In CSF CD4+ T cells, IFN-gamma+ IL-4- cell percentages were markedly elevated in CIDP compared with OND, but not in VN, resulting in a significant increase of intracellular IFN-gamma/IL-4 ratio in CIDP, even in the absence of CSF pleocytosis. The nonresponders to intravenous immunoglobulins (IVIGs) showed a significantly lower IFN-gamma- IL-4+ CD4+ T cell percentage, and tended to have a higher intracellular IFN-gamma/IL-4 ratio than the responders in CSF. Marked upregulation of Th1 cytokine, IL-17, and downregulation of Th2 cytokines, together with infiltration of IFN-gamma-producing CD4+ T cells are useful markers for CIDP, while several Th2 cytokines are upregulated in VN in CSF.     

Impaired interleukin-12 production in multiple sclerosis patients.

Multiple Sclerosis (MS), a disease of the human central nervous system, is believed to be a T cell mediated autoimmune disorder with genetic and environmental influences. Interleukin-12 (IL-12), a proinflammatory cytokine produced primarily by antigen presenting cells is a potent inducer of interferon-gamma (IFN-gamma) and other Th1 cytokines that may play an important role in MS pathogenesis. We have investigated IL-12 production induced by the T cell independent pathway in untreated and IFN-beta treated MS patients, healthy individuals and other neurological disease (OND) patients in response to the human pathogen Staphylococcus aureus. We report that peripheral blood mononuclear cells (PBMC) from untreated MS patients produce normal amounts of the biologically active IL-12 p70 heterodimer but significantly less free IL-12 p40 heavy chain than PBMC from both healthy and disease controls when challenged in vitro with Staphylococcus aureus. Both mRNA expression of the inducible IL-12 p40 chain and protein levels were found to be reduced in untreated MS patients. No decrease in the production of the IL-12 p40 was seen in MS patients on IFN-beta therapy. The decreased production of IL-12 p40 heavy chain is not attributed to increased IL-10 secretion, a defect in the production of cytokines by macrophages or the number of cytokine producing cells. The factor(s) responsible for the decrease in p40 remain to be determined. Since IL-12 p40 antagonizes the biological activity of IL-12 in vitro and in vivo, identification of a defect in the 'natural' antagonist of IL-12, may provide the basis for immune therapy.     

Prior poliomyelitis-IVIg treatment reduces proinflammatory cytokine production

The postpolio syndrome (PPS) is characterized by progressive disabilities decades after recovery from the acute paralytic disease. There are reports on intrathecal inflammatory reactions in PPS, including increased expression of cytokines by cerebrospinal fluid (CSF) mononuclear cells (CSF-MC). This is potentially of relevance for the clinical condition. We here explored if cytokine expression in the CSF of PPS patients could be modulated by high-dose intravenous immunoglobulins (IvIg). The expression of TNF-alpha, IFN-gamma, IL-10 and IL-4 mRNAs was measured by real-time RT-PCR in CSF and peripheral blood mononuclear cells (PBMC) of 16 PPS patients before, and 6-8 weeks after IvIg treatment, and in 26 patients with noninflammatory other neurological diseases (OND). TNF-alpha, IFN-gamma and IL-10 CSF mRNA levels were elevated in samples from untreated persons with PPS compared to OND. Upon IvIg treatment, IFN-gamma and TNF-alpha mRNA levels were dramatically reduced, while IL-10 remained unchanged. Placebo-controlled studies are now warranted to evaluate if IvIg treatment also has any effects on the clinical manifestations of PPS.     

Th1 dominance in HAM/TSP and the optico-spinal form of multiple sclerosis versus Th2 dominance in mite antigen-specific IgE myelitis

To clarify the Th1/Th2 balance in spinal cord inflammation, we used ELISA to measure the total and allergen-specific IgE in 69 patients with clinically definite multiple sclerosis (MS), including 24 patients with the optico-spinal form of MS, 45 with HAM/TSP, 30 HTLV-I carriers without HAM/TSP, 40 patients with acute myelitis, 43 with neurodegenerative disorders, and 42 healthy subjects, and flow cytometry to study the intracellular IFNgamma-positive versus IL-4-positive cell ratio (intracellular IFNgamma/IL-4 ratio) in peripheral blood CD4(+) T cells in 40 patients with MS, including 17 patients with the optico-spinal form of MS, 23 with HAM/TSP, 22 with acute myelitis, 23 with neurodegenerative disorders, and 36 healthy subjects. Patients with HAM/TSP showed a significantly higher intracellular IFNgamma/IL-4 ratio, lower IL-4(+)/IFN-gamma(-) cell percentages, lower total IgE level, and lower frequency of cedar pollen-specific IgE than did the controls. The patients with optico-spinal MS showed a significantly higher intracellular IFNgamma/IL-4 ratio and higher IL-4(-)/IFN-gamma(+) cell percentages than the controls even at remission or in the convalescence phase. In contrast, in the patients with acute myelitis, the total serum IgE level and the frequency of mite antigen-specific IgE were significantly elevated in comparison to the controls, while those having mite antigen-specific IgE myelitis showed a significantly lower IFNgamma/IL-4 ratio in the CD4(+) T cells in comparison to the controls. These findings suggest that the Th1 cell response is predominant in HAM/TSP and optico-spinal MS, whereas the Th2 cell response is predominant in mite antigen-specific IgE myelitis.     

IL-12/IL-12R system in multiple sclerosis

IL-12/IL-12 receptor (IL-12R) system orchestrates the Th1 pathway of the immune system by maintaining one of the major bridges between innate and adaptive immune responses. Here, we studied both sides of this system in patients with multiple sclerosis (MS) and in controls. MS patients displayed elevated IL-12Rbeta1 and IL-12Rbeta2 expression on PHA-activated T cells compared to healthy subjects. Higher percentages of IL-12Rbeta1 and IL-12Rbeta2 positive T cells in cerebrospinal fluid (CSF) compared to blood were observed both in MS and other neurological diseases (OND). In contrast, numbers of IL-12 secreting blood mononuclear cells (MNC) were similar in MS and controls. The functional importance of high IL-12Rbeta2 in MS was underlined by the finding that IL-12 stimulated IFN-gamma production and proliferation of PHA-activated T cells correlated with levels of IL-12Rbeta2 expression. Our data indicates a dysregulation of the IL-12/IL-12R system in MS. It is suggested that even in the absence of increased IL-12 levels, the net effect of IL-12 might be augmented in MS by elevated expression of its receptor.     

Augmented type 1 cytokines and human endogenous retroviruses specific immune responses in patients with acute multiple sclerosis

In vitro antigen- and mitogen-stimulated cytokine production were analysed in multiple sclerosis (MS) patients with either acute (AMS) or stable (SMS) disease and in healthy controls (HC). We also investigated whether immune responses to human endogenous retroviruses (HERV) could be detected in MS and whether these immune responses would be correlated with disease status by analysing cytokine production after stimulation of PBMC with HERV peptides. Results showed that mitogen-stimulated IL-2 and IFN-gamma was augmented and IL-10 was decreased in AMS compared to both SMS and healthy controls. Whereas the production of the metabolically active IL-12 (p70 heterodimer), was comparable in SMS, AMS and HC, production of the total IL-12 (p70 heterodimer and the p40 chain) were augmented in SMS compared to both AMS and HC. HERV-peptides IL-2 and IFN-gamma production was more frequent and more potent in AMS compared to both SMS patients and HC. HERV-specific type 2 cytokine production was more frequent and potent in SMS compared to AMS and HC. Thus a prevalent type 1 cytokine profile was seen in AMS patients, while IL-10 production predominated in SMS individuals.     

The effects of MPTP on the activation of microglia/astrocytes and cytokine/chemokine levels in different mice strains

The effects of MPTP on two mouse strains with different MPTP sensitivities and immunological backgrounds were compared: MPTP-sensitive C57BL/6 mice (B6) with a propensity for Th1 and less MPTP-sensitive BALB/c mice (BALB) with a propensity for Th2. It was found that acute MPTP treatment induced behavioral dysfunction, activated microglia/astrocytes, and increased the levels of IL-10, IL-12(p40) IL-13, IFN-gamma, and MCP-1 in CSF in B6, but not in BALB. This suggests that variances in immunological backgrounds might be a major contributing factor in sensitivity differences to MPTP.     

Modulation of T cell responses in HTLV-1 carriers and in patients with myelopathy associated with HTLV-1

OBJECTIVE: Human T lymphotropic virus-type 1 (HTLV-1) activates the immune system leading to a persistent and exacerbated T-cell response with increased production of IFN-gamma and TNF-alpha. Overproduction of pro-inflammatory cytokines is correlated with the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), although some HTLV-1 carriers also show high levels of these cytokines. In this study, the ability of regulatory cytokines and cytokine antagonists to inhibit spontaneous IFN-gamma production was investigated. METHOD: IFN-gamma levels were measured by ELISA before and after addition of cytokines or anti-cytokines. RESULTS: Addition of IL-10 significantly reduced spontaneous IFN-gamma synthesis in cell cultures from HTLV-1 carriers, while no differences were observed in HAM/TSP patients. There was also a tendency to decreased IFN-gamma levels in cell cultures from HTLV-1 carriers with exogenous addition of TGF-beta. In paired analysis, neutralization of IL-2 significantly decreased IFN-gamma production in HTLV-1 carriers but not in HAM/TSP patients. Neutralization of IL-15 was less effective than neutralization of IL-2 in modulating IFN-gamma production. In HTLV-1 carriers, anti-IL-2 and simultaneous addition of anti-IL-2 and anti-IL-15 decreased IFN-gamma synthesis by 46 and 64%, respectively, whereas in patients with HAM/TSP simultaneous neutralization of both anti-cytokines only decrease IFN-gamma levels by 27%. CONCLUSIONS: Although a large proportion of HTLV-1 carriers produced high levels of pro-inflammatory cytokines similar to those observed in HAM/TSP patients, immune response can be downregulated by cytokines or cytokine antagonists in most HTLV-1 carriers. This modulation can be an important step in the prevention of tissue damage and progression from the HTLV-1 carrier state to HAM/TSP.     

Tc1/Tc2 and Th1/Th2 balance in Asian and Western types of multiple sclerosis, HTLV-I-associated myelopathy/tropical spastic paraparesis and hyperIgEaemic myelitis

CD8+ T cells, like CD4+ T cells, can differentiate into at least two subsets with distinct cytokine patterns: Tc1 cells produce Th1-like cytokines and Tc2 cells produce Th2-like cytokines. To clarify the immunopathological roles of Tc1 and Tc2 cells in central nervous system (CNS) inflammation, we examined intracellular cytokines in CD8+ and CD4+ T cells by flow cytometry and analyzed the Tc1/Tc2 balance as well as the Th1/Th2 balance in 80 patients with various CNS inflammatory diseases, including 20 with optico-spinal multiple sclerosis (OS-MS), 21 with conventional MS (C-MS), 22 with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and 17 with hyperIgEaemic myelitis. Twenty-two healthy subjects were also examined as controls. Patients with OS-MS showed a significantly higher percentage of INF-gamma+IL-4- CD8+ T cells as well as CD4+ T cells and a significantly higher intracellular interferon-gamma (IFN-gamma)/interleukin-4 (IL-4) ratio both in CD8+ and CD4+ T cells throughout the relapse and remission phases than the healthy controls. Furthermore, the patients with OS-MS showed a significantly lower percentage of INF-gamma-IL-4+ CD4+ T cells as well as CD8+ T cells during the relapse phase than the healthy controls. On the other hand, the patients with C-MS showed a significantly higher percentage of IFN-gamma-IL-4+ CD8+ T cells in addition to more IFN-gamma+IL-4- CD4+ T cells during the relapse phase than the healthy controls. The HAM/TSP patients showed a significantly higher percentage of INF-gamma+IL-4- CD8+ T cells and a significantly higher intracellular IFN-gamma/IL-4 ratio in CD8+ T cells than the healthy controls. In contrast, in hyperIgEaemic myelitis, in addition to a significantly lower intracellular IFN-gamma/IL-4 ratio in CD4+ T cells, a tendency toward a lower intracellular IFN-gamma/IL-4 ratio in CD8+ T cells in comparison to the healthy controls was observed. These results clarified for the first time the distinct Tc1/Tc2 balance in each disease condition as follows: Tc1 cell response is predominant in OS-MS and HAM/TSP, while Tc2 cell response is predominant in hyperIgEaemic myelitis and at relapse phase of C-MS. Furthermore, our results suggest that CD8+ T cells play an adjunctive role in disease induction and the clinical course of MS.     

Cerebrospinal fluid cytokines in AIDS dementia complex

Summary We evaluated cerebrospinal fluid (CSF) and serum concentrations of interleukin-1-alpha (IL-1 alpha), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) in 30 patients with AIDS dementia complex (ADC), and in 20 HIV-seronegative subjects with other neurological diseases (OND). CSF TNF alpha, IL-1-alpha and IL-6 were more frequently detectable in ADC patients than in OND subjects. These cytokines were also detectable in CSF of ADC patients with minimal symptoms. In contrast, the majority of both ADC and OND patients did not contain detectable serum levels of cytokines. Our data support the notion of intrathecal synthesis of cytokines in ADC patients and raise the possibility that activated macrophages may play a significant role in the pathogenesis of ADC.     

A longitudinal study on IL-2, sIL-2R, IL-4 and IFN-gamma in multiple sclerosis CSF and serum.

The cerebrospinal fluid (CSF) and serum levels of interleukin-2 (IL-2), soluble IL-2 receptor (sIL-2R), interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were longitudinally investigated in 20 multiple sclerosis (MS) patients. There were 80 paired CSF and serum samples (range 2-8 per patient) covering a 1-5 year (mean 2.5 year) period. Increased levels of IL-2 and sIL-2R were found in 56 and 71%, respectively, of MS sera. In all patients, one or several sera (totally 89%) exhibited values above the normal range for either one of the components or both. The occurrence of IL-2 or sIL-2R positive CSF specimens was much lower, 15 and 9%, respectively. Only 3 MS sera (from one patient) had clearly detectable IL-4 and no CSF samples were definitely positive. IFN-gamma was undetectable in all serum and CSF specimens. No correlations were found between the immunological parameters and the clinical disease activity. The cytokine patterns in MS give strong support for the presence of a systemic T-cell activation. Furthermore, the data argue for a predominant activation of an IL-2- and sIL-2R-producing but not IL-4-producing T-helper (Th) lymphocyte subpopulation, Th1/CD4 + CD45R + cells.     

CSF cytokine and chemokine profiles in acute disseminated encephalomyelitis

We simultaneously measured 16 cytokines/chemokines in cerebrospinal fluid (CSF) from 14 patients with acute disseminated encephalomyelitis (ADEM) and 20 controls using a fluorescent bead-based immunoassay. A variety of cytokines, such as IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IFN-gamma, TNF-alpha, G-CSF and MIP-1beta, were significantly elevated in ADEM. In particular, G-CSF showed a marked 38-fold increase compared to the control mean. Significant positive correlations with inflammatory parameters in CSF, such as cell counts and protein levels, were found for IFN-gamma, IL-6 and IL-8. In contrast, IL-17 produced by activated CD4(+) memory T cells was not increased. The results suggested that various cytokines related to activation of macrophages/microglias and Th(1) and Th(2) cells are upregulated in CSF in ADEM.     

Activated T lymphocytes in cerebrospinal fluid of patients with HTLV-I-associated myelopathy (HAM/TSP)

In order to detect activated T lymphocytes in the cerebrospinal fluid (CSF) of patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we studied CSF lymphocytes in untreated patients with HAM/TSP and other neurological diseases (OND). Dual-immunofluorescence staining technique was performed using fluorescence microscopy. No significant difference in the CD4+/CD8+ ratio of CSF lymphocytes was observed between HAM/TSP patients and patients with OND. However, both CD4+ and CD8+ CSF lymphocytes of HAM/TSP patients contained higher percentages of HLA-DR-positive cells than those of patients with OND (P less than 0.05), suggesting that the activated CSF T lymphocytes were composed of both CD4+ and CD8+ subsets in patients with HAM/TSP.     

Serum and CSF levels of IL-2, sIL-2R, TNF-alpha, and IL-1 beta in chronic progressive multiple sclerosis: expected lack of clinical utility

We measured interleukin-2 (IL-2), soluble IL-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) by ELISA in paired sera and CSF from 50 chronic progressive multiple sclerosis (CPMS) patients during worsening disability, 19 patients with other neurologic diseases (OND), and in sera from 40 healthy volunteers. In the CPMS patients, 28% (14/50), 10% (5/50), 16% (8/50), and 6% (3/50) had elevated serum levels of IL-2, sIL-2R, TNF-alpha and IL-1 beta, respectively, compared with healthy controls. The only analyte we detected in the CSF was IL-2 in 1 CPMS patient (1/50, 2%). We also saw elevated serum sIL-2R in 16% (3/19) of OND patients. We found no significant difference in mean levels of serum sIL-2R between the 3 groups. Our study, the largest to date of CPMS patients, shows that serum and CSF levels of IL-2, sIL-2R, TNF-alpha, or IL-1 beta are not sensitive for, and the serum sIL-2R level is not specific for, CPMS. Therefore, measurement of these analytes will not be clinically useful for therapeutic or prognostic purposes in the majority of CPMS patients.     

Intra vitam lumbar and post mortem ventricular cerebrospinal fluid immunoreactive interleukin-6 in Alzheimer's disease patients

OBJECTIVES: In view of contradictory findings in previous studies, to examine the diagnostic value of interleukin-6 measurements in cerebrospinal fluid (CSF) of Alzheimer's disease patients. MATERIAL AND METHODS: Interleukin-6-immunoreactivity (IL-6-IR) was measured in 169 intra vitam lumbar and 21 post mortem ventricular CSF samples of patients with probable and neuropathologically confirmed Alzheimer's disease (AD), non-AD dementias (NAD), neurological disorders without cognitive impairment (OND) and controls (CON) using a specific sandwich enzyme immunoassay. RESULTS: Intra vitam lumbar samples had significantly elevated (P < 0.03) IL-6-IR not only in the AD, but also in the NAD and OND group compared with controls. AD patients with late onset (> 65 years) had slightly (P > 0.05) higher values than patients with early onset (< 65 years). In post mortem ventricular fluid, differences among groups did not reach significance (P > 0.05). CONCLUSION: We conclude that elevations of CSF IL-6-IR can not serve as a diagnostic marker of the disease, but, hypothetically, could reflect presence or activity of IL-6 mediated immunological phenomena in single AD patients.     

CSF and serum immune parameters in Sydenham's chorea: evidence of an autoimmune syndrome?

Previous investigations have suggested that Sydenham's chorea (SC) may be an autoantibody mediated disorder. We examined this autoimmune hypothesis by measuring Th1 (IFN-gamma, IL-12) and Th2 (IL-4, IL-10) cytokines, oligoclonal bands (OCB) and anti-basal ganglia antibodies (ABGA). CSF IL-4 was elevated in 31% of acute SC and 50% of persistent SC. CSF IL-10 was also elevated in 31% of acute SC but 0% of persistent SC. CSF IFN-gamma was undetectable in all patients. Serums IL-4, IL-10 and IL-12 were elevated in acute compared to persistent SC. OCB were found in 46% of acute SC, ABGA were in 93% of acute SC and 50% of persistent SC was of IgG(1) and IgG(3) subclass. These findings support an autoantibody pathogenesis.     

Multiple sclerosis: expression of CD1a and production of IL-12p70 and IFN-gamma by blood mononuclear cells in patients on combination therapy with IFN-beta and glatiramer acetate compared to monotherapy with IFN-beta

Current therapy of multiple sclerosis (MS) with interferon-beta (IFN-beta) or glatiramer acetate (GA) has modest effects on the course of MS. Both compounds affect several immune variables, like expression of cell surface molecules and cytokine levels. Here we compared untreated MS, therapy with IFN-beta alone and combined with GA, and healthy controls (HC), regarding expression on HLA-DR+ blood mononuclear cells (MNC) of CD1a that is a cell surface molecule with capacity to present glycolipids to T cells, and of CD80 and CD86 which are costimulatory molecules that activate Th1 and Th2 responses. Cytokine production by MNC was also measured. Flow cytometry and ELISA were used. Cross-sectional comparisons revealed that untreated MS patients had higher CD1a+ HLA-DR+ MNC and lower IL-10 production compared to patients treated with IFN-beta or IFN-beta+GA or HC. Untreated MS patients also had higher spontaneous IFN-gamma and IL-12p70 production compared to MS patients treated with IFN-beta+GA or HC, but not when compared to MS patients on monotherapy with IFN-beta. Low CD1a+ HLA-DR+ MNC and low spontaneous production of IL-12p70 and IFN-gamma were more pronounced in patients treated with IFN-beta+GA than with IFN-beta alone. In order to clarify whether these changes reflect disease activity or treatment effects, we performed a follow up study. Nineteen MS patients with disease progression, despite monotherapy with IFN-beta for more than one year; were re-examined after one to three and four to six months of treatment with IFN-beta+GA. This combination therapy was associated with normalization of CD1a+ HLA-DR+ MNC, IL-12p70 and IFN-gamma. It remains to be shown whether these immunological changes imply a clinical benefit. Follow up studies of immune variables versus clinical effects during combined therapy of MS with IFN-beta+GA are ongoing.     

Elevated levels of interleukin-6 in serum and cerebrospinal fluid of HTLV-I-associated myelopathy/tropical spastic paraparesis

A significant elevation of interleukin-6 (IL-6) level was observed both in serum (mean 0.455 +/- 0.251) and in cerebrospinal fluid (CSF) (mean 0.043 +/- 0.016) obtained from 13 patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) when compared to that of either asymptomatic carriers (mean 0.181 +/- 0.074 and 0.021 +/- 0.015, respectively) or controls (mean 0.208 +/- 0.119 and 0.021 +/- 0.015, respectively). The differences were statistically significant between HAM/TSP and asymptomatic carrier for serum (P less than 0.05) or CSF (P less than 0.01). The correlation indexes between serum IL-6 and anti-HTLV-I antibody titers in serum and CSF were 0.61 (P less than 0.06) and 0.67 (P less than 0.05), respectively. Both the cell count and protein level in CSF correlated with CSF IL-6 activity at 0.68 (P less than 0.01) and 0.56 (P less than 0.05), respectively. The results demonstrate that IL-6 may contribute to the production of anti-HTLV-I antibody, and signs of slight inflammation are present in the central nervous system in HAM/TSP.     

Increased intrathecal TGF-β1, but not IL-12, IFN-γ and IL-10 levels in Alzheimer’s disease patients

Abstract An inflammatory response has been hypothesised to be involved in the pathogenesis of primary dementias, above all Alzheimer’s disease (AD). This study was aimed at evaluating interleukin (IL)-12 and a panel of related cytokine levels in paired CSF and sera of demented patients. IL-12 (p70 heterodimer and total IL-12 p40 chain), interferon (IFN)-γ, IL-10 and transforming growth factor (TGF)-β1 levels were measured in 30 patients with probable Alzheimer’s disease (PrAD), 57 patients with other dementing disorders, including probable vascular dementia (PrVD), Parkinson’s disease (PD) and normal pressure hydrocephalus (NPH), and 25 cognitively normal control subjects. In the presence of unchanged concentrations of IL-12, IFN-γ and IL-10, the mean CSF level of TGF-β1 and the correspondent TGF-β1 index, but not the serum level, were significantly increased in PrAD compared to controls and PrVD, whereas no difference was found vs. NPH and PD. Our results support the pathophysiological role of TGF-β1 system in AD.