Intracellular Accumulation and Secretion of YKL-40 (CHI3L1) in the Course of DMSO-Induced HL-60 Cell Differentiation.

YKL-40 (CHI3L1) is a matrix glycoprotein stored in human neutrophil-specific granules and released upon activation. While it is implicated in inflammation, cancer progression, and cell differentiation, its exact physiological role remains unclear. This study investigated the intracellular expression and secretion of YKL-40 by untreated and DMSO-treated HL-60 cells in association with surface expression of CD11b and CD66b throughout the differentiation process (up to 120 h). Secreted YKL-40 protein and mRNA levels of YKL-40, CD66b, and CD11b were measured by ELISA and quantitative RT-PCR, respectively. The intracellular YKL-40 and surface CD11b and CD66b expression were assessed by flow cytometry. A significant increase in CD11b expression confirmed DMSO-induced differentiation of HL-60 cells. Upon DMSO stimulation, YKL-40 mRNA expression increased in a time-dependent manner, unlike CD66b. The lack of CD66b (a granulocyte maturation and activation marker) on the surface of HL-60 cells might suggest that DMSO treatment did not induce full maturation or activation. The intracellular YKL-40 protein expression was increasing up to 96 h of DMSO treatment and then declined. YKL-40 secretion into the culture medium was detectable only at later time points (96 and 120 h), which was correlated with a decreased proliferation of DMSO-treated HL-60 cells. These findings suggest sequential changes in YKL-40 production and secretion during DMSO-induced differentiation of HL-60 cells and might contribute to a better understanding of YKL-40's involvement in both physiological processes and disease development, including multiple sclerosis.

Analysis of Side Effects Following Vaccination Against COVID-19 Among Individuals With Multiple Sclerosis Treated With DMTs in Poland.

Background and Objectives: Since vaccination against COVID-19 is available for over a year and the population of immunized individuals with autoimmune disorders is higher than several months before, an evaluation of safety and registered adverse events can be made. We conducted a large study of side effects following the COVID-19 vaccine among patients with multiple (MS) sclerosis treated with disease-modifying therapies (DMTs) and analyzed factors predisposing for particular adverse events. Methods: We gathered data of individuals with MS treated with DMTs from 19 Polish MS Centers, who reported at least one adverse event following COVID-19 vaccination. The information was obtained by neurologists using a questionnaire. The same questionnaire was used at all MS Centers. To assess the relevance of reported adverse events, we used Fisher's exact test, t-test, and U-Menn-Whutney test. Results: A total of 1,668 patients with MS and reports of adverse events after COVID-19 vaccination were finally included in the study. Besides one case marked as "red flag", all adverse events were classified as mild. Pain at the injection site was the most common adverse event, with a greater frequency after the first dose. Pain at the injection site was significantly more frequent after the first dose among individuals with a lower disability (EDSS ≤2). The reported adverse events following immunization did not differ over sex. According to age, pain at the injection site was more common among individuals between 30 and 40 years old, only after the first vaccination dose. None of the DMTs predisposed for particular side effects. Conclusions: According to our findings, vaccination against COVID-19 among patients with MS treated with DMTs is safe. Our study can contribute to reducing hesitancy toward vaccination among patients with MS.

Safety of Vaccines against SARS-CoV-2 among Polish Patients with Multiple Sclerosis Treated with Disease-Modifying Therapies.

(1) Background: The present study aims to report the side effects of vaccination against coronavirus disease 2019 (COVID-19) among patients with multiple sclerosis (MS) who were being treated with disease-modifying therapies (DMTs) in Poland. (2) Methods: The study included 2261 patients with MS who were being treated with DMTs, and who were vaccinated against COVID-19 in 16 Polish MS centers. The data collected were demographic information, specific MS characteristics, current DMTs, type of vaccine, side effects after vaccination, time of side-effect symptom onset and resolution, applied treatment, relapse occurrence, and incidence of COVID-19 after vaccination. The results were presented using maximum likelihood estimates of the odds ratio, t-test, Pearson's chi-squared test, Fisher's exact p, and logistic regression. The statistical analyses were performed using STATA 15 software. (3) Of the 2261 sampled patients, 1862 (82.4%) were vaccinated with nucleoside-modified messenger RNA (mRNA) vaccines. Mild symptoms after immunization, often after the first dose, were reported in 70.6% of individuals. Symptoms included arm pain (47.5% after the first dose and 38.7% after the second dose), fever/chills/flu-like symptoms (17.1% after the first dose and 20.5% after the second dose), and fatigue (10.3% after the first dose and 11.3% after the second dose). Only one individual presented with severe side effects (pro-thrombotic complications) after vaccination. None of the DMTs in the presented cohort were predisposed to the development of side effects. Nine patients (0.4%) had a SARS-CoV-2 infection confirmed despite vaccination. (4) Conclusions: Vaccination against SARS-CoV-2 is safe for people with MS who are being treated with DMTs. Most adverse events following vaccination are mild and the acute relapse incidence is low.

NK Cell Induced T Cell Anergy Depends on GRAIL Expression.

NK cells (natural killer cells) being a part of the innate immune system have been shown to be involved in immunoregulation of autoimmune diseases. Previously we have shown that HINT1/Hsp70 treatment induced regulatory NK cells ameliorating experimental autoimmune encephalomyelitis (EAE) course and CD4+ T cells proliferation. NK cells were isolated from mice treated with HINT1/Hsp70 and co-cultured with proteolipid protein (PLP)-stimulated CD4+ T cells isolated from EAE mice. Cell proliferation was assessed by thymidine uptake, cytotoxicity by lactate dehydrogenase (LDH) release assay and fluorescence activated cell sorting (FACS) analysis, protein expression by Western blot, mRNA by quantitative RT-PCR. Gene related to anergy in lymphocytes (GRAIL) expression was downregulated by specific siRNA and GRAIL overexpression was induced by pcDNA-GRAIL transfection. HINT1/Hsp70 pretreatment of EAE SJL/J mice ameliorated EAE course, suppressed PLP-induced T cell proliferation by enhancing T cell expression of GRAIL as GRAIL downregulation restored T cell proliferation. HINT1/Hsp70 treatment induced immunoregulatory NK cells which inhibited PLP-stimulated T cell proliferation not depending on T cell necrosis and apoptosis. This immunoregulatory NK cell function depended on NK cell expression of GRAIL as GRAIL downregulation diminished inhibition of NK cell suppression of T cell proliferation. Similarly GRAIL overexpression in NK cells induced their regulatory function. HINT1/Hsp70 treatment generated regulatory NK cells characterized by expression of GRAIL.

Hollow silica capsules for amphiphilic transport and sustained delivery of antibiotic and anticancer drugs.

Hollow mesoporous silica capsules (HMSC) are potential drug transport vehicles due to their biocompatibility, high loading capacity and sufficient stability in biological milieu. Herein, we report the synthesis of ellipsoid-shaped HMSC (aspect ratio ∼2) performed using hematite particles as solid templates that were coated with a conformal silica shell through cross-condensation reactions. For obtaining hollow silica capsules, the iron oxide core was removed by acidic leaching. Gas sorption studies on HMSC revealed mesoscopic pores (main pore width ∼38 Å) and a high surface area of 308.8 m2 g-1. Cell uptake of dye-labeled HMSC was confirmed by incubating them with human cervical cancer (HeLa) cells and analyzing the internalization through confocal microscopy. The amphiphilic nature of HMSC for drug delivery applications was tested by loading antibiotic (ciprofloxacin) and anticancer (curcumin) compounds as model drugs for hydrophilic and hydrophobic therapeutics, respectively. The versatility of HMSC in transporting hydrophilic as well as hydrophobic drugs and a pH dependent drug release over several days under physiological conditions was demonstrated in both cases by UV-vis spectroscopy. Ciprofloxacin-loaded HMSC were additionally evaluated towards Gram negative (E. coli) bacteria and demonstrated their efficacy even at low concentrations (10 µg ml-1) in inhibiting complete bacterial growth over 18 hours.

Multiple sclerosis: Presence of serum antibodies to lipids and predominance of cholesterol recognition.

A lot of available data on lipid immunology in multiple sclerosis (MS) have been derived from studies using synthetic lipids, therefore the role of lipids in the immunopathogenesis of MS remains poorly defined. The present study on the lipid response in MS was performed on native lipids from autopsied brain tissue. For this, lipid fractions (n = 9) were prepared from MS (n = 3) and control (n = 2) white matter according to the Folch procedure and were characterized depending on their solubility in chloroform/methanol. TLC showed that, in brain from MS cases, neutral lipids were rich in cholesterol and cholesterol esters while lipids from control brains displayed a predominance of phospholipids. MS serum IgG and IgM were found to bind to MS brain lipid fractions with a higher efficacy (p < 0.05) than the control serum. F(ab)2 fractionation revealed that MS serum IgG binding depended on a specific antibody-type of recognition. Pre-adsorption of serum with cholesterol, galactocerebrosides, sulfitides, and phosphatidylinositol prior to ELISA with MS brain lipids, showed that cholesterol diminished IgG and IgM binding up to 70%. Experiments with synthetic lipids confirmed the predominance of cholesterol binding by MS serum. Our results demonstrate that IgG and IgM fractions from MS serum specifically and predominantly recognize native cholesterol and cholesterol esters isolated from the brain tissue of patients with MS. © 2017 Wiley Periodicals, Inc.

Dysregulated RNA-Induced Silencing Complex (RISC) Assembly within CNS Corresponds with Abnormal miRNA Expression during Autoimmune Demyelination.

MicroRNAs (miRNAs) associate with Argonaute (Ago), GW182, and FXR1 proteins to form RNA-induced silencing complexes (RISCs). RISCs represent a critical checkpoint in the regulation and bioavailability of miRNAs. Recent studies have revealed dysregulation of miRNAs in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE); however, the function of RISCs in EAE and MS is largely unknown. Here, we examined the expression of Ago, GW182, and FXR1 in CNS tissue, oligodendrocytes (OLs), brain-infiltrating T lymphocytes, and CD3(+)splenocytes (SCs) of EAE mic, and found that global RISC protein levels were significantly dysregulated. Specifically, Ago2 and FXR1 levels were decreased in OLs and brain-infiltrating T cells in EAE mice. Accordingly, assembly of Ago2/GW182/FXR1 complexes in EAE brain tissues was disrupted, as confirmed by immunoprecipitation experiments. In parallel with alterations in RISC complex content in OLs, we found downregulation of miRNAs essential for differentiation and survival of OLs and myelin synthesis. In brain-infiltrating T lymphocytes, aberrant RISC formation contributed to miRNA-dependent proinflammatory helper T-cell polarization. In CD3(+) SCs, we found increased expression of both Ago2 and FXR1 in EAE compared with nonimmunized mice. Therefore, our results demonstrate a gradient in expression of miRNA between primary activated T cells in the periphery and polarized CNS-infiltrating T cells. These results suggest that, in polarized autoreactive effector T cells, miRNA synthesis is inhibited in response to dysregulated RISC assembly, allowing these cells to maintain a highly specific proinflammatory program. Therefore, our findings may provide a mechanism that leads to miRNA dysregulation in EAE/MS.

High CD6 and low chemokine receptor expression on peripheral blood lymphocytes correlates with MRI gadolinium enhancement in MS.

Correlation between gadolinium-enhancing [Gd(+)] lesions on MRI and expression of CD6 molecules and a group of chemokine receptors on peripheral blood (PB) and cerebrospinal fluid (CSF) immune cells was measured in multiple sclerosis (MS) patients. Twenty remitting-relapsing MS patients with (n=10) and without (n=10) Gd(+) lesions entered the study. mRNA and surface expression of CD6 and CCR1, CCR2, CCR3 and CCR5 was measured by immunostaining and flow cytometry. Expression of mRNA and surface staining for CD6 in PB T lymphocytes was increased in Gd(+) compared to Gd(-) patients (p<0.01; p<0.05, respectively). CD6 mRNA correlated with the number and size of Gd(+) lesions (r=0.67, and r=0.65 respectively). mRNA and surface expression for CCR1, CCR2, and CCR3 in PB cells was lower in Gd(+) compared to Gd(-) MS patients (p<0.05, p<0.05). The frequency of cells co-expressing CD6 with CCR1 and CCR5 was low in PB T lymphocytes and high in CSF (p<0.05, p<0.05). These results suggest that Gd(+) correlates with increased expression of CD6 and decreased expression of chemokine receptors on PB T lymphocytes. Co-expression of CD6 with CCR1 and CCR5 predisposes cells for transmigration into CSF.

HINT1 peptide/Hsp70 complex induces NK-cell-dependent immunoregulation in a model of autoimmune demyelination.

Heat shock proteins (Hsps) interact with the immune system and have been shown to contribute to immunoregulation. As efficient chaperones, Hsps bind many peptides and these complexes have many yet-to-be-clarified functions. We have shown that Hsp70 is complexed within the mouse CNS with peptide CLAFHDISPQAPTHFLVIPK derived from histidine triad nucleotide-binding protein-1 (HINT138₋57/Hsp70). Only this complex, in contrast to other peptides complexed with Hsp70, was able to prevent experimental autoimmune encephalomyelitis (EAE) by induction of immunoregulatory mechanisms dependent on NK cells. Pretreatment of proteolipid protein peptide 139₋151(PLP139₋151) sensitized SJL/J mice with HINT138₋57/Hsp70 prevented the development of EAE, suppressed PLP139₋151-induced T-cell proliferation, and blocked secretion of IL-17. HINT138₋57 /Hsp70 stimulation of NK cells depended on synergistic activation of two NK-cell receptors, CD94 and NKG2D. NK cells with depleted CD94 or with blocked NKG2D did not inhibit PLP139₋151-induced spleen cell (SC) proliferation. The HINT138₋57/Hsp70 complex enhanced surface expression of the NKG2D ligand-H60. Downstream signaling of CD94 and NKG2D converged at the adaptor proteins DAP10 and DAP12, and in response to HINT138₋57 /Hsp70 stimulation, expression of DAP10 and DAP12 was significantly increased in NK cells. Thus, we have shown that the HINT138₋57 /Hsp70 complex affects NK-cell function by enhancing NK-cell-dependent immunoregulation in the EAE model of autoimmune demyelination.

MicroRNA-146a negatively regulates the immunoregulatory activity of bone marrow stem cells by targeting prostaglandin E2 synthase-2.

The molecular mechanisms that regulate the immune function of bone marrow-derived mesenchymal stem cells (BMSCs) are not known. We have shown previously that freshly isolated BMSCs when induced to express neuronal stem cell markers lose immunoregulatory function when transferred into mice sensitized to develop experimental autoimmune encephalomyelitis. Recently, microRNAs (miRs) have been shown to be involved in the regulation of several immune responses in both innate and acquired immunity. We now show that among several differentially expressed miRs, miR-146a was strongly upregulated in neuronally differentiated when compared with miR-146a expression in freshly isolated BMSCs or control BMSCs cultured in parallel but in nondifferentiating medium. Inhibition of miR-146a with a selective antagomir restored the immunoregulatory activity of nBMSCs. We mapped miR-146a to its multiple predicted target mRNA transcripts and found that miR-146a was predicted to block PGE2 synthase (ptges-2). We then showed that Ptges-2 was directly targeted by miR-146a using a luciferase reporter assay. Furthermore, increased expression of miR-146a in BMSCs correlated with inhibition of PGE synthase-2 and inhibition of PGE2 release. Accordingly, inhibition of miR-146a restored synthesis of PGE2. These data support the conclusion that miR-146a plays a critical role in the control of the immunoregulatory potential of BMSCs.

Immunoregulatory function of bone marrow mesenchymal stem cells in EAE depends on their differentiation state and secretion of PGE2.

Bone marrow mesenchymal stem cells (BMSC)-induced amelioration of experimental autoimmune encephalomyelitis (EAE) was diminished with neuronal differentiantion of BMSC (nBMSC). BMSC secreted large amounts of PGE2, compared to nBMSC, which correlated with higher efficacy to EAE inhibition. EAE mice treated with PGE2 inhibitor, meloxicam showed decreased serum levels of PGE2 and in parallel decreased inhibitory effect on EAE course. In addition, high levels of PGE2 secretion correlated with high expression of indoleamine-2,3-dioxygenase (IDO). Meloxicam blocked IDO expression in BMSC transferred mice indicating functional relation between PGE2 and IDO induction. The current findings demonstrates PGE2 involvement in BMSC-induced inhibition of EAE and provides a mechanistic link between BMSC-derived PGE2 and IDO-dependent immunoregulation of this autoimmune condition.

Immune regulation of multiple sclerosis by transdermally applied myelin peptides.

OBJECTIVE: Antigen-specific therapy targeting selective inhibition of autoreactive responses holds promise for controlling multiple sclerosis (MS) without disturbing homeostasis of the whole immune system. Key autoantigens in MS include myelin proteins, such as myelin basic protein (MBP), proteolipid protein (PLP), and myelin oligodendrocyte glycoprotein (MOG). In this study, we examined the effect of transdermal therapy with myelin peptides on immune responses in the skin, lymph nodes, and peripheral blood immune cells of MS patients. METHODS: In a 1-year placebo-controlled study, 30 patients with relapsing-remitting MS were treated transdermally with a mixture of 3 myelin peptides: MBP85-99, PLP139-151, and MOG35-55, or placebo. The phenotype of immune cells in the skin was assessed using immunohistochemistry. Cell populations in lymph nodes were analyzed using flow cytometry. In peripheral blood immune cells, cytokine production was measured by enzyme-linked immunosorbent assay, and myelin-specific proliferation was examined by carboxyfluorescein succinimidyl ester-based assay. RESULTS: We found that myelin peptides applied transdermally to MS patients activated dendritic Langerhans cells in the skin at the site of immunization and induced a unique population of granular dendritic cells in local lymph nodes. In the periphery, transdermal immunization with myelin peptides resulted in the generation of type 1, interleukin-10-producing regulatory T cells, suppression of specific autoreactive proliferative responses, and suppression of interferon-γ and transforming growth factor-ß production. INTERPRETATION: We demonstrate for the first time the immunoregulatory potential of transdermal immunization with myelin peptides in MS patients.

Notch3 inhibition in myelin-reactive T cells down-regulates protein kinase C theta and attenuates experimental autoimmune encephalomyelitis.

Among its varied functions, Notch signaling is involved in peripheral T cells responses. The activation and polarization of CD4(+) T cells toward a Th1 lineage are essential steps in the pathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis. Inhibition of all four Notch receptors with a gamma-secretase inhibitor was shown to block Th1-type polarization and to attenuate the symptoms of experimental autoimmune encephalomyelitis. In this study, we have examined the role of individual Notch receptors in proliferation, cytokine production, and encephalitogenic potential of PLP-reactive T cells. Specific induction of Notch1 and Notch3 transcripts were noted in PLP-reactive T cells upon Ag stimulation. However, using gamma-secretase inhibitor and Abs blocking distinct Notch receptors, we have found that selective inhibition of Notch3, but not Notch1, receptor abrogated proliferation, Th1- and Th17-type responses of PLP-reactive T cells. Moreover, Notch3 inhibition in T cells correlated with the down-regulated expression of protein kinase Ctheta, a kinase with important regulatory function within mature T cells. Thus, selective inhibition of the Notch3 receptor may have important effects on peripheral T cell responses and may offer a new attractive target in treating autoimmune diseases, including multiple sclerosis.

Stem cells ameliorate EAE via an indoleamine 2,3-dioxygenase (IDO) mechanism.

Syngeneic, pluripotent Lin(-)Sca1(+) bone marrow stem cells (SC), transferred to mice with experimental autoimmune encephalomyelitis, a model of multiple sclerosis, enhanced recovery, prevented relapses and promoted myelin repair. SC-treated mice showed elevated interferon-gamma production and induction of indoleamine 2,3-dioxygenase (IDO) in CD11c(+) dendritic cells (DC). IDO induction was specific since in the presence of IDO-producing CD11c(+) DC, PLP stimulated T cell proliferation was inhibited and the IDO-inhibitor, 1-MT, abrogated the SC effect. Relapse prevention during chronic disease correlated with decreased responsiveness to PLP(178-191) and MBP(85-99). Thus, pluripotent SC induce IDO in DC leading to inhibition of antigen reactivity and spreading in EAE.

Overcoming failure to repair demyelination in EAE: gamma-secretase inhibition of Notch signaling.

In multiple sclerosis (MS), myelin destroyed by the immune attack is not effectively repaired by oligodendrocytes (OLs) and MS foci eventually undergo glial scarring. Although oligodendrocyte precursor cells (OPCs) are normally recruited to the lesion areas, they fail to mature and remyelinate the damaged fibers. Activation of the Notch pathway has been shown to inhibit OPC differentiation and to hamper their ability to produce myelin during CNS development. We have recently shown that inhibition of gamma-secretase within the CNS of SJL/J mice with experimental autoimmune encephalomyelitis (EAE) blocks Notch pathway activation in OLs, promotes remyelination, reduces axonal damage and significantly enhances clinical recovery from the disease. Our results suggest that inhibiting the non-myelin permissive environment maintained by Notch pathways within the mature CNS offers a new strategy for treating autoimmune demyelination, including MS.

EAE tolerance induction with Hsp70-peptide complexes depends on H60 and NKG2D activity.

Inflammation leads to induction of tissue stress conditions that might contribute to the generation of mechanisms limiting ongoing immune responses. We have shown previously that peptides derived from brain tissue of mice with experimental autoimmune encephalomyelitis (EAE) complexed with the chaperone heat shock protein 70 (Hsp70-pc) induce an NK-cell-dependent tolerance for subsequent EAE sensitization. We now present data that showed that the MHC class I-related glycoprotein H60 determines Hsp70-pc-induced EAE inhibition. Hsp70-pc led to significant and selective up-regulation of H60 expression in SJL/J mice, and Ab-blocking of H60 expression led to loss of EAE tolerance. Similarly, blocking of the NK cell receptor for H60, NKG2D, also reversed the Hsp70-pc-induced EAE inhibition. In contrast, in C57BL/6 mice H60 was not expressed, and Hsp70-pc-induced tolerance was not detected. The NK cell mediated Hsp70-pc-induced tolerance to EAE was dependent on modulation of dendritic cells function leading to diminished T cell reactivity to PLP. As, no increase of H60 expression on T cells from EAE mice immunized with PLP was detected, and no enhanced loss of CD3+ H60+ over CD3+ H60- cells in Hsp70-pc-induced EAE tolerance was found direct killing of H60+ PLP-reactive cells seems not to be involved in the Hsp70-pc-induced tolerance induction. We have provided evidence that Hsp70-pc-induced tolerance for EAE, mediated by NK cells, involves induction of H60 ligand and its interaction with NKG2D receptor. NK cells tolerization of EAE depends on altered dendritic cells activity leading to enhanced death of Ag reactive cells.

Soluble Nogo-A, an inhibitor of axonal regeneration, as a biomarker for multiple sclerosis.

BACKGROUND: CNS axons display a poor regenerative response to injury. In multiple sclerosis (MS), failure of damaged axons to regenerate may be a major factor underlying non-reversible neurologic dysfunction. Nogo is a development-related molecule inhibiting axonal regeneration and is a major component of CNS myelin. METHODS: CSF from 114 patients with remitting relapsing MS (RR-MS) and secondary progressive MS (SP-MS) and 153 controls, as well as CNS tissue from 3 patients with MS and 2 controls, were used for this study. RESULTS: We found soluble 20 kDa Nogo-A product in 96% (110/114) of CSF samples from patients with MS compared with 0/18 from meningo-encephalomyelitis, 0/125 from control subjects with other neurologic diseases, and 0/10 from CNS autoimmune diseases. Nogo-A products were present both in RR-MS and SP-MS, as well as in early cases of the disease, but not in neuromyelitis optica. The same Nogo A product was detected in CNS tissue from all patients with MS but not in control CNS tissue. CONCLUSION: Soluble Nogo-A may be specific for the CSF of patients with multiple sclerosis and its presence may predict failure of axonal regeneration within the CNS.

Brain-derived heat shock protein 70-peptide complexes induce NK cell-dependent tolerance to experimental autoimmune encephalomyelitis.

Heat shock proteins (Hsp) are markedly up-regulated at sites of inflammation during autoimmune diseases like experimental autoimmune encephalomyelitis (EAE). In this study, we show that Hsp70-peptide complexes (pc) isolated from brains of mice with EAE prevented the development of EAE clinically and pathologically when administered before proteolipid protein 139-151 (PLP139-151) immunization. In contrast, pure Hsp70 or Hsp70-pc derived from brains of healthy mice or other inflamed tissue did not modulate the expression of EAE. In animals in which EAE had been suppressed by Hsp70-pc, lymphocytes showed increased cell death in response to PLP139-151 that correlated with elevated IFN-gamma and NO production. Coculture of spleen cells from Hsp70-pc immunized mice with spleen cells from untreated EAE mice, in addition to depletion experiments, showed that NK cells reduced reactivity to PLP139-151. Transfer of NK cells from Hsp70-pc-immunized mice to recipients sensitized for EAE abolished disease development. Thus, we propose that Hsp70 demonstrate the ability to bind to peptides generated during brain inflammation and to induce a regulatory NK cell population that is capable of preventing subsequent autoimmunization for EAE.