CD44 splice variant involvement in the chronic inflammatory disease of the spinal cord: HAM/TSP

Splice variants of CD44 molecule-harboring exon 10 (v6), often called v6 variants (v6v), are shown to confer tumor progressive, metastatic or invasive capacities. Furthermore, CD44 molecule on activated T-cells are shown to be required for infiltration of these cells into the inflammatory site and for accelerated immune response. Human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is caused by HTLV-I infection and characterized by spastic paraparesis and urinary disturbance with perivascular HTLV-I-infected and activated CD4+ T-cell infiltration. In order to explore the underlying mechanism causing the disease after HTLV-I infection, we analyzed CD44 variant expression on peripheral blood mononuclear cells (PBMC) and in the spinal cord specimens from patients with HAM/TSP, and compared them with those from other HTLV-I-infected individuals and controls. We found that v6v expression with special direct link of exons 10 (v6) and 14(v10) was highly expressed in PBMC from patients with HAM/TSP and that v6v and CD4 double positive T-cell infiltration into the spinal cord lesion of HAM/TSP. This combination of CD44 splice variant has not been previously reported in the study of chronic inflammatory disorders and may be a marker molecule for T-cells infiltrating into the central nervous system (CNS), especially the spinal cord.

Molecular pathologic analysis of the tonsil in HTLV-I-infected individuals

Little is known about the role of the tonsils in HTLV-I infection. We performed molecular pathologic studies of tonsils in individuals positive or negative for anti-HTLV-I antibodies (HTLV-I-Ab) to clarify histologic characteristics of tonsils in HTLV-I infection. We collected tonsils and peripheral blood samples from patients who underwent tonsillectomy in a prospective manner. HTLV-I-Ab in serum was examined and presence of HTLV-I provirus was detected by polymerase chain reaction (PCR) in extracted DNA of both peripheral blood and tonsils. Histopathologic and immunohistochemical evaluations of tonsils were performed. HTLV-I seropositivity and PCR detection of HTLV-I provirus matched perfectly. Tonsil samples from seropositive individuals showed atrophy of the mantle zone and high numbers of T cells in the marginal zone compared with findings in HTLV-I-negative samples. HTLV-I provirus could be detected only from extracted DNA of extrafollicular areas. PCR in situ hybridization also showed positive signals in some mononuclear cells located in the marginal zone. There was a significant correlation between HTLV-I proviral load in tonsils and in peripheral blood. These results suggest the presence of characteristic histologic changes and deviated localization of HTLV-I-infected cells in the tonsils of individuals positive for HTLV-I.

Linkage analysis of candidate myelin genes in familial multiple sclerosis

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. A complex genetic etiology is thought to underlie susceptibility to this disease. The present study was designed to analyze whether differences in genes that encode myelin proteins influence susceptibility to MS. We performed linkage analysis of MS to markers in chromosomal regions that include the genes encoding myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMGP), and myelin oligodendrocyte glycoprotein (MOG) in a well-characterized population of 65 multiplex MS families consisting of 399 total individuals, 169 affected with MS and 102 affected sibpairs. Physical mapping data permitted placement of MAG and PLP genes on the Genethon genetic map; all other genes were mapped on the Genethon genetic map by linkage analysis. For each gene, at least one marker within the gene and/or two tightly linked flanking markers were analyzed. Marker data analysis employed a combination of genetic trait model-dependent (parametric) and model-independent linkage methods. Results indicate that MAG, MBP, OMGP, and PLP genes do not have a significant genetic effect on susceptibility to MS in this population. As MOG resides within the MHC, a potential role of the MOG gene could not be excluded.

Increased levels of soluble Fas ligand in CSF of rapidly progressive HTLV-1-associated myelopathy/tropical spastic paraparesis patients

The interaction of Fas ligand (FasL) with Fas-bearing cells induces apoptosis and contributes to the negative regulation of peripheral T-cell responses. Membrane-bound FasL is cleaved by a matrix metalloproteinase-like enzyme and converted to a soluble form (sFasL). Recent studies suggest that such sFasL can cause systemic tissue damage. Here we report that serum and CSF levels of soluble FasL (sFasL) are markedly higher in three active phase patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). All of these patients showed higher sFasL levels in CSF than in serum. Although the HTLV-1 proviral load of patients showed no correlation with serum or with CSF sFasL, CSF sFasL levels of 14 HAM/TSP patients correlated with the anti-HTLV-1 antibody titer and neopterin concentration in CSF. These results indicate that sFasL mediated mechanisms may contribute to the inflammatory process and subsequent spinal tissue damage seen in HAM/TSP patients.

Detection of human T-lymphotropic virus type I p40tax protein in cerebrospinal fluid cells from patients with human T-lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis

We investigated the role of viral transcripts of human T-lymphotropic virus type I (HTLV-I) in the cerebrospinal fluid (CSF) cells and peripheral blood mononuclear cells (PBMCs) of patients with human T-lymphotropic virus type I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). To detect the HTLV-I p40tax protein, we developed a new sensitive method of immunohistochemistry combined with tyramide signal amplification and quantitative analysis. Seven patients with HAM/TSP were examined. As controls, four patients with other neurological diseases were examined; two of these patients were infected with HTLV-I and the other two were not. Both the CSF cells and PBMCs were reacted with a monoclonal antibody, Lt-4, for p40tax protein, followed by secondary antibody labeled with horseradish peroxidase. This was visualized by fluorescein directly labeled with tyramide and the number of positive cells was quantified with a Laser Scanning Cytometer. In the samples from patients with HAM/TSP, the HTLV-I p40tax protein was successfully detected by tyramide signal amplification, but not without it. In HAM/TSP patients, 0.04-1.16% of the CSF cells and 0.02-0.54% of PBMCs were positive for the HTLV-I p40tax protein, respectively. The expression of the HTLV-I p40tax protein in the CSF cells was more frequent than that in PBMCs in both HAM/TSP patients and HTLV-I carriers, and was also more frequent in the patients with HAM/TSP of shorter duration of illness. This technique could be a powerful tool to investigate the pathogenic mechanism of diseases associated with HTLV-I.

Genetic control and dynamics of the cellular immune response to the human T-cell leukaemia virus, HTLV-I

About 1% of people infected with the human T-cell leukaemia virus, type 1 (HTLV-I) develop a disabling chronic inflammatory disease of the central nervous system known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP have a vigorous immune response to HTLV-I, and it has been widely suggested that this immune response, particularly the HTLV-I-specific cytotoxic T-lymphocyte (CTL) response, causes the tissue damage that is seen in HAM/TSP. In this paper we summarize recent evidence that a strong CTL response to HTLV-I does in fact protect against HAM/TSP by reducing the proviral load of HTLV-I. We conclude that HTLV-I is persistently replicating at a high level, despite the relative constancy of its genome sequence. These results imply that antiretroviral drugs could reduce the risk of HAM/TSP by reducing the viral load, and that an effective anti-HTLV-I vaccine should elicit a strong CTL response to the virus. The dynamic nature of the infection also has implications for the epidemiology and the evolution of HTLV-I.

HLA alleles determine human T-lymphotropic virus-I (HTLV-I) proviral load and the risk of HTLV-I-associated myelopathy

The risk of disease associated with persistent virus infections such as HIV-I, hepatitis B and C, and human T-lymphotropic virus-I (HTLV-I) is strongly determined by the virus load. However, it is not known whether a persistent class I HLA-restricted antiviral cytotoxic T lymphocyte (CTL) response reduces viral load and is therefore beneficial or causes tissue damage and contributes to disease pathogenesis. HTLV-I-associated myelopathy (HAM/TSP) patients have a high virus load compared with asymptomatic HTLV-I carriers. We hypothesized that HLA alleles control HTLV-I provirus load and thus influence susceptibility to HAM/TSP. Here we show that, after infection with HTLV-I, the class I allele HLA-A*02 halves the odds of HAM/TSP (P < 0.0001), preventing 28% of potential cases of HAM/TSP. Furthermore, HLA-A*02(+) healthy HTLV-I carriers have a proviral load one-third that (P = 0.014) of HLA-A*02(-) HTLV-I carriers. An association of HLA-DRB1*0101 with disease susceptibility also was identified, which doubled the odds of HAM/TSP in the absence of the protective effect of HLA-A*02. These data have implications for other persistent virus infections in which virus load is associated with prognosis and imply that an efficient antiviral CTL response can reduce virus load and so prevent disease in persistent virus infections.

Clonal expansion within CD4+ and CD8+ T cell subsets in human T lymphotropic virus type I-infected individuals

To investigate the diversity of the T cell repertoire involved in human T lymphotropic virus type I (HTLV-I) infections, peripheral blood T cell subsets were analyzed by using a PCR-based assay that permits determination of complementarity-determining region 3 (CDR3) length variation in TCR Vbeta transcripts. In two of four asymptomatic HTLV-I carriers and in four of five patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), mono- or oligoclonal expansions were detected in the CD4+ T cell subset. In one patient with adult T cell leukemia, a specific clone bearing Vbeta7 was detected in the CD4+ T cell subset. In contrast, clonal expansion was not observed in the CD4 T cell subsets of three individuals with asymptomatic HTLV-II infection or in our previous studies of a large number of uninfected individuals. Oligoclonal expansions in the CD8+ T cell subset were detected in all subjects, including the patient with adult T cell leukemia. No differences in the number of expanded clones were noted between asymptomatic carriers and in patients with HAM/TSP and there was no obvious restriction in the TCR V region usage. Direct sequencing revealed no significant bias in the CDR3 motifs utilized by the predominant clones. This report is the first direct demonstration of clonal expansions within fractionated T cell subsets (CD4+ and CD8+) in HTLV-I infections and suggests that 1) clonal expansion of CD4+ T lymphocytes likely occurs as a direct result of infection and 2) polyclonal CD8+ T cell expansion occurs frequently and independently of disease association.

Clonal Expansion Within CD4+ and CD8+ T Cell Subsets in Human T Lymphotropic Virus Type I-Infected Individuals

To investigate the diversity of the T cell repertoire involved in human T lymphotropic virus type I (HTLV-I) infections, peripheral blood T cell subsets were analyzed by using a PCR-based assay that permits determination of complementarity-determining region 3 (CDR3) length variation in TCR Vβ transcripts. In two of four asymptomatic HTLV-I carriers and in four of five patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), mono- or oligoclonal expansions were detected in the CD4+ T cell subset. In one patient with adult T cell leukemia, a specific clone bearing Vβ7 was detected in the CD4+ T cell subset. In contrast, clonal expansion was not observed in the CD4 T cell subsets of three individuals with asymptomatic HTLV-II infection or in our previous studies of a large number of uninfected individuals. Oligoclonal expansions in the CD8+ T cell subset were detected in all subjects, including the patient with adult T cell leukemia. No differences in the number of expanded clones were noted between asymptomatic carriers and in patients with HAM/TSP and there was no obvious restriction in the TCR V region usage. Direct sequencing revealed no significant bias in the CDR3 motifs utilized by the predominant clones. This report is the first direct demonstration of clonal expansions within fractionated T cell subsets (CD4+ and CD8+) in HTLV-I infections and suggests that 1) clonal expansion of CD4+ T lymphocytes likely occurs as a direct result of infection and 2) polyclonal CD8+ T cell expansion occurs frequently and independently of disease association.

Analysis of HTLV-I proviral load in 202 HAM/TSP patients and 243 asymptomatic HTLV-I carriers: high proviral load strongly predisposes to HAM/TSP

In order to examine the effect of HTLV-I proviral load on the pathogenesis of HAM/TSP, we measured the HTLV-I proviral load in peripheral blood mononuclear cells (PBMC) from a large number of HAM/TSP patients and asymptomatic HTLV-I carriers. To measure the proviral load, we used an accurate and reproducible quantitative PCR method using a dual-labeled fluorogenic probe (ABI PRISM 7700 Sequence Detection System). The mean +/- standard error of mean (s.e.m.) HTLV-I proviral copy number per 1 x 10(4) PBMC was 798 +/- 51 (median 544) in 202 HAM/TSP patients; 120 +/- 17 (median 34) in 200 non HAM-related (general) asymptomatic HTLV-I carriers (RC); and 496 +/- 82 (median 321) in 43 asymptomatic HTLV-I carriers genetically related to HAM/TSP patients (FA). The prevalence of HAM/TSP rises exponentially with log (proviral load) once the proviral load exceeds 1% PBMC. The HTLV-I proviral load of female patients with HAM/TSP was significantly higher than that of male patients, however there was no significant difference in proviral load between sexes in RC. There was a significant correlation between the proviral load and the concentration of neopterin in CSF of HAM/TSP patients. These results indicate that the HTLV-I proviral load in PBMC may be related to the inflammatory process in the spinal cord lesion. The increased proviral load in FA suggests the existence of genetic factors contributing to the replication of HTLV-I in vivo.

Predominant expression of Fas ligand mRNA in CD8+ T lymphocytes in patients with HTLV-1 associated myelopathy

To determine if Fas ligand (FasL) mediated apoptosis is involved in the pathogenesis of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we examined the expression of FasL mRNA in fresh uncultured peripheral blood mononuclear cells (PBMC) from 17 Japanese patients with HAM/TSP, four adult T-cell leukemia/lymphoma (ATL) patients, three asymptomatic HTLV-1 carriers and three normal individuals. Using competitive PCR with primers specific for FasL mRNA, we demonstrated that nine of 17 HAM/TSP and one of four ATL patients expressed significant levels of FasL mRNA, whereas asymptomatic carriers, normal controls and both HTLV-1 infected and uninfected T-cell lines did not. Cell separation analysis following PCR revealed that FasL mRNA was expressed in CD8 + T lymphocytes. FasL mRNA was preferentially expressed in patients with increased proviral load and longer duration of clinical illness. These results suggest that FasL mediated mechanisms contribute to the pathogenesis of HAM/TSP.

Human CD4+ T lymphocytes recognize a highly conserved epitope of human T lymphotropic virus type 1 (HTLV-1) env gp21 restricted by HLA DRB1*0101

HTLV-1 causes two distinct human diseases, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T cell leukaemia/lymphoma (ATL). Persistently infected individuals carry a risk of <1% of developing either disease. These basic epidemiological data imply that virus-host interactions, especially immunogenetic factors, influence the outcome of infection. Several studies showed that the HLA class II DR1 DQ5 haplotype is over-represented in HAM/TSP, but rare in ATL. Therefore, we selected four patients with HAM/TSP and one seronegative control who all carried the HLA DR1 DQ5 haplotype. We analysed the CD4+ T lymphocyte response against eight synthetic peptides of HTLV-1 envelope (env) glycoprotein gp21, a crucial target antigen in HAM/TSP. The first of two immunodominant epitopes corresponded to a domain of the HTLV-1 envelope protein which had previously been shown to be essential for HTLV-1 envelope function. The second immunodominant epitope overlapped a highly conserved sequence of the retroviral transmembrane envelope protein. DR1 (DRB1*0101)-restricted T lymphocytes were activated by the conserved peptide sequence in nanomolar concentrations. In contrast, this conserved sequence can also induce non-specific, cAMP-mediated immunosuppressive effects on T cells when added in micromolar concentrations to culture media, as shown by Haraguchi S, Good RA, James-Yarish M, Cianciolo GJ, Day NK, Proc Natl Acad Sci USA 1995; 92:5568-71. Hence, HTLV-1 env gp21 might exert either stimulating immunological or immunosuppressive effects in HTLV-1-infected individuals, depending on the level of its expression and the presence of HLA DRB1*0101.

Alteration of cytokine levels by fosfomycin and prednisolone in spontaneous proliferation of cultured lymphocytes from patients with HTLV-I-associated myelopathy (HAM/TSP)

Fosfomycin has recently been reported as an antibiotic with immunomodulatory activities. To evaluate the possibility of clinical administration of fosfomycin in patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), the effects of this agent on the HTLV-I-induced in vitro phenomenon were studied. The influence of fosfomycin on in vitro spontaneous proliferation (SP) of peripheral blood mononuclear cells (PBMCs) from four patients with HAM/TSP was measured by thymidine incorporation into the cells, and the concentration of several cytokines in the culture supernatants was examined in three HAM/TSP patients. Enzyme-linked immunosorbent assays (ELISAs) were employed to detect the concentrations of interleukin-4 (IL-4), IL-6, IL-10, interferon-gamma (IFN-gamma), transforming growth factor-beta1 (TGF-beta1), and macrophage inflammatory protein-1alpha (MIP-1alpha). The data were compared to the changes by prednisolone which is known to regulate the HTLV-I-associated in vitro phenomenon and to have a therapeutic benefit in patients with HAM/TSP. Production of IL-6, IFN-gamma and MIP-1alpha from the spontaneously proliferating cells were demonstrated. Fosfomycin could not suppress the HTLV-I-associated SP, but had the properties to decrease the levels of TGF-beta1 and MIP-1alpha. It was also demonstrated that the concentrations of IFN-gamma and MIP-1alpha in the cultures in the presence of prednisolone were apparently decreased, suggesting a possible involvement of these cytokines in the pathogenesis of HAM/TSP. These findings support the hypothesis that fosfomycin may have immunomodulatory potentials in HTLV-I-related cellular interactions in a different manner from ordinary immunomodulatory agents.

Preferential recognition of synthetic peptides from HTLV-I gp21 envelope protein by HLA-DRB1 alleles associated with HAM/TSP (HTLV-I-associated myelopathy/tropical spastic paraparesis)

To determine CD4+ T-cell epitopes of HTLV-I-envelope protein recognized by the HLA alleles associated with HAM/TSP, we established 20 CD4+ T-cell lines from peripheral blood mononuclear cells (PBMCs) of naive healthy donors using a panel of synthetic peptides spanning the entire length of HTLV-I-envelope proteins, gp46 and gp21. We quantitated the precursor frequencies of HTLV-1-envelope specific CD4+ T-cells and analyzed epitope specificity in the context of HLA alleles. The precursor frequencies ranged from 3.0 to 10.6 per 10(7) PBMCs in the naive healthy donors. The CD4+ T-cell epitopes of HTLV-I-envelope protein were clustered in amino acids 76 to 90, 136 to 160, 171 to 185 and 196 to 210 of gp46, and in amino acids 366 to 400 and 436 to 485 of gp21. The CD4+ T-cell epitopes of gp21 were preferentially recognized by HLA-DRB1 0101 and 1502 which were known to be associated with HAM/TSP. Thus, it was suggested that HTLV-I gp21 might contain the major CD4+ T-cell epitopes recognized by HLA-DRB1 alleles of HAM/TSP.

Detection of the soluble form of the Fas molecule in patients with multiple sclerosis and human T-lymphotropic virus type I-associated myelopathy

We evaluated the presence of soluble Fas molecule (sFas) in the cerebrospinal fluids (CSF) and the sera of patients with multiple sclerosis (MS) or human T-lymphotropic virus type I (HTLV-I) associated myelopathy (HAM) using an enzyme-linked immunosorbent assay (ELISA). Patients with multiple sclerosis in the active phase had higher sFas serum levels than control (p < 0.005). In addition, significantly increased serum levels of sFas were found in patients with HAM (p < 0.005). We found a significantly increased CSF levels of sFas in patients with HAM and patients with MS in the active stage (p < 0.005). These results suggest that serum sFas may be related to clinical activity in patients with MS and that Fas may play an important role in the pathogenesis of HAM.

Intrathecal humoral immune response in HAM/TSP in relation to HLA haplotype analysis

INTRODUCTION

In HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), we correlated human leukocyte antigen (HLA) haplotypes to the fine specificities of intrathecally synthesized IgG antibodies against HTLV-1.

PATIENTS AND METHODS

HLA haplotypes of HAM/TSP patients were determined by the standard NIH microcytotoxicity test and family HLA studies. IgG antibodies against HTLV-1 synthetic peptides in paired CSF and serum were measured by enzyme immunoassay, and intrathecal synthesis of antibodies was evaluated.

RESULTS

HAM/TSP patients with particular HLA haplotypes (A24Cw7B7DR1DQ5, A2Cw7B7DR1DQ5, A24Cw-B52DR15DQ6, A11Cw1B54DR4DQ4, and A24Cw1B54DR4DQ4) showed more frequently intrathecal synthesis of antibodies against HTLV-1 synthetic peptides, especially against HTLV-1 env gp21 synthetic peptides.

CONCLUSION

In HAM/TSP, a retrovirus-induced human chronic inflammatory disease of the CNS, this is the first report to provide evidence that the intrathecal antiviral immune response is influenced by immunogenetic factors of the HLA complex.

Mutation rates in LTR of HTLV-1 in HAM/TSP patients and the carriers are similarly high to Tax/Rex-coding sequence

The genomic sequence of human T-cell leukemia virus type 1 (HTLV-1) is highly conserved, although minor sequence variations enable classification of the isolates into several subgroups. We previously reported, however, that the Tax-coding sequence of HTLV-1 genome is highly variable in a random fashion within individuals with HAM/TSP and asymptomatic carriers. Here, we describe frequent base substitutions in the LTR sequence similarly to those in Tax-coding sequence. These observations indicate that frequent mutations are not unique to the sequence encoding the most effective antigen for cytotoxic T lymphocytes, but also seen in the LTR, a non-coding sequence. Thus, frequent mutations seem to occur during the viral replication process rather than the selection of rare mutants by immune surveillance.

Biased expression of T cell receptor genes characterizes activated T cells in multiple sclerosis cerebrospinal fluid

To better characterize the inflammatory response that occurs in the nervous system in multiple sclerosis (MS), T-cell receptor (TCR) gene expression was quantified from cerebrospinal fluid (CSF) cells of 21 patients with active disease. Unstimulated CSF cells expressed each of 22 different TCR beta chain variable region (V beta) gene families in proportion to their expression in simultaneously sampled peripheral blood. When CSF cells from individuals with MS were expanded by in vitro culture in T-cell growth factor/interleukin 2 and 4-containing medium (TCGF/IL2/IL4), restricted numbers of V beta genes were expressed. In many subjects, expanded CSF cells expressed predominantly V beta 2. In contrast to CSF, expansion of corresponding peripheral blood mononuclear cells (PBMC) in TCGF/IL2/IL4 resulted in persistent expression of all V beta gene families. Within individuals, different V beta genes were overexpressed by PBMC compared with CSF cells. No effect of the HLA haplotype of the individual on CSF V beta gene expression was observed. Expanded CSF cells retained their capacity to respond to mitogen stimulation, but the proliferative response to myelin basic protein (MBP) was not enhanced. Finally, freshly obtained CSF cells stimulated directly with MBP also expressed a limited number of V beta genes, although these were generally different from patterns observed following stimulation with TCGF/IL2/IL4. Thus, restricted populations of T cells capable of responding to TCGF/IL2/IL4, presumably reflecting in vivo activated cells, are compartmentalized in the nervous system in MS.

Tumor necrosis factor (TNF) microsatellite haplotypes in relation to extended haplotypes, susceptibility to diseases associated with the major histocompatibility complex and TNF secretion

TNFabc microsatellite haplotypes were determined on normal, type I diabetes and multiple sclerosis Caucasian MHC haplotypes in family studies. Although independent examples of conserved extended haplotypes usually had the same TNFabc haplotypes, there were a number of exceptions, suggesting that these loci are more mutable than most loci in the human MHC. Some TNFabc haplotypes were characteristic of only one extended haplotype, whereas others were shared by several different extended haplotypes. From the analysis of TNFabc on extended haplotype fragments, and assuming that the fragments arose by ancient homologous crossing over, it was possible to "map" TNF and how that it was somewhat closer to HLA-B than the complement region, corresponding to the physical map of this region. TNF haplotype associations with type I diabetes and multiple sclerosis were attributable to the known extended haplotype associations of these diseases. There was also a trend for higher TNF-alpha secretion by peripheral blood mononuclear cells from individuals homozygous for [HLA-B8, SC01, DR3] than from individuals homozygous for [HLA-B7, SC31, DR2].

A complete genomic screen for multiple sclerosis underscores a role for the major histocompatability complex. The Multiple Sclerosis Genetics Group

Multiple sclerosis (MS), an inflammatory autoimmune demyelinating disorder of the central nervous system, is the most common cause of acquired neurological dysfunction arising in the second to fourth decades of life. A genetic component to MS is indicated by an increased relative risk of 20-40 to siblings compared to the general population (lambda s), and an increased concordance rate in monozygotic compared to dizygotic twins. Association and/or linkage studies to candidate genes have produced many reports of significant genetic effects including those for the major histocompatability complex (MHC; particularly the HLA-DR2 allele), immunoglobulin heavy chain (IgH), T-cell receptor (TCR) and myelin basic protein (MBP) loci. With the exception of the MHC, however, these results have been difficult to replicate and/or apply beyond isolated populations. We have therefore conducted a two-stage, multi-analytical genomic screen to identify genomic regions potentially harbouring MS susceptibility genes. We genotyped 443 markers and 19 such regions were identified. These included the MHC region on 6p, the only region with a consistently reported genetic effect. However, no single locus generated overwhelming evidence of linkage. Our results suggest that a multifactorial aetiology, including both environmental and multiple genetic factors of moderate effect, is more likely than an aetiology consisting of simple mendelian disease gene(s).

Diversity of intrathecal antibody synthesis against HTLV-I and its relation to HTLV-I associated myelopathy

The humoral immune response against human T-cell lymphotropic virus type I (HTLV-I) in the central nervous system (CNS) compartment and in the blood was investigated by enzyme immunoassay using 16 synthetic peptides corresponding to HTLV-I core and envelope sequences. We evaluated paired samples of cerebrospinal fluid and serum from HTLV-I seropositive Japanese patients, classified as follows: HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP; n = 39), patients with spinal cord disease ascribed to either HAM/TSP or to some concomitant, HTLV-I-unrelated disease (possible HAM/TSP; n = 6) or carriers without any clinical signs of HAM/TSP (n = 15). HTLV-I-peptide-specific intrathecal antibody synthesis was found in 79% of HAM/TSP patients, but only in 20% of carriers without HAM/TSP. The group of carriers without HAM/TSP showed local synthesis for some peptides (on average 0.3 peptides per patient). In most HAM/TSP patients, however, there was a diverse intrathecal immune response to several HTLV-I synthetic peptides (on average against 3.6 peptides per HAM/TSP patient), most frequently against gag p19 100-130, env gp21 458-488, and env gp46 175-199 and 288-317. The intrathecal antibody synthesis against several HTLV-I determinants may represent a pathogenic immune response in HAM/TSP and is possibly related to the infiltration of virus-infected T-cells in the spinal cord.

Frequent mutation in pX region of HTLV-1 is observed in HAM/TSP patients, but is not specifically associated with the central nervous system lesions

Human T-cell leukemia virus type 1 (HTLV-1) is an etiologic agent of adult T-cell leukemia (ATL) and of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Recently it has been reported that defective HTLV-1 provirus was detected frequently in the central nervous system (CNS) lesions of HAM/TSP patients. Here we investigated sequence variations of the pX region of HTLV-1 in the CNS and peripheral blood lymphocytes (PBL) of the same patient. The results analyzing 9-13 clones isolated from each specimen indicated that the pX region is highly variable within a patient with HAM/TSP, and the mutations were found at almost random positions within the sequences analyzed. The frequency and pattern of those mutations did not appear to differ significantly between the CNS and PBL of the same patient, although they differed among patients. Similarly, frequent mutations were observed in an asymptomatic carrier of HTLV-1, although the variability was moderate, suggesting that the high variability of the pX sequence is not a specific event in HAM/TSP. However, one asymptomatic carrier showed much less frequent variations very similarly to an ATL patient; both of them harbored clonally expanded infected cells. Thus the apparent low variability was explained by clonal selection of a single species of the provirus by the clonal proliferation of infected cells. These results clearly indicate that mutations including defectives are not specifically associated with the CNS lesions in HAM/TSP patients, but suggest that the random mutations simply reflect the rate of viral replication in individuals and the variants were not inherited frequently.

[Immune response against myelin basic protein and analysis of T-cell receptor in multiple sclerosis]

Human demyelinating disease, multiple sclerosis, is now though to be caused by autoreactive T cells against several antigens in central nervous system. In experimental allergic encephalomyelitis, animal model of the disease, successful treatment is reported using a monoclonal antibody to T-cell receptor (TCR) of encephalitogenic T cells. Analoging this model, researchers are now trying to intervene T cells suspected to elicit the disease. For this purpose, myelin basic protein, one of the candidate CNS antigens, reactive T cells and usage of TCR in those cells are extensively examined. Although no convincing result was obtained so far because of complexity of the disease and a genetic background of human beings, T cell intervention may be beneficial to some patients with this disease.

Apoptosis of T lymphocytes in the spinal cord lesions in HTLV-I-associated myelopathy: a possible mechanism to control viral infection in the central nervous system

Immunocytochemical staining of spinal cords from five autopsied patients with HAM/TSP was performed using the monoclonal antibody TIA-1, a marker of cytotoxic T lymphocytes (CTL). Many TIA-1+, CD8+ cells are distributed in active inflammatory lesions. The number of TIA-1+ cells is related to the amount of HTLV-I proviral DNA in situ. The protein TIA-1 has been associated with the induction of apoptosis in target cells. In active inflammatory lesions, we found cells undergoing apoptosis, most of them identified as helper-inducer CD45RO T lymphocytes, which were consistent with in vivo cellular tropism of HTLV-I in patients with HAM/TSP. These findings suggest that CTL-induced apoptosis of T lymphocytes may be one of the possible mechanisms which eliminate HTLV-I-infected cells from the central nervous system. In addition, many T lymphocytes in the inflammatory lesions expressed bcl-2 oncoprotein, suggesting that infiltrated T lymphocytes may be resistant to apoptosis. Expression of bcl-2 oncoprotein may explain the longstanding inflammatory process in the central nervous system of HAM/TSP.

The T-cell response to myelin basic protein in familial multiple sclerosis: diversity of fine specificity, restricting elements, and T-cell receptor usage

Indirect evidence suggests that an autoimmune response to myelin basic protein (MBP) may be involved in the pathogenesis of multiple sclerosis (MS). In MS, several reports have suggested that restricted T-cell populations respond to MPB, as in inbred rodents with the MS disease model experimental allergic encephalomyelitis. In experimental allergic encephalomyelitis, the T-cell repertoire to MBP varies between strains, and in MS it is likely that the response to MBP is also best defined under conditions where genetic differences between subjects are controlled. In this report, the fine specificity of the T-cell response to MBP was assessed in three families, each with multiple individuals affected with MS. We found that (1) comparable frequencies of MBP-reactive T-cell lines were obtained from peripheral blood of MS patients and their healthy siblings. Human leukocyte antigen (HLA) identical sibling pairs discordant for MS had similar frequencies of MBP-reactive T-cell lines. (2) A broad spectrum of MBP epitopes was recognized by T-cell lines from all individuals studied. Within a family, the fine specificity of MBP recognition showed little or no overlap between individuals, even between HLA identical siblings. (3) Recognition of MBP epitopes occurred in the context of different HLA class II alleles. At least four DR alleles each served as restricting elements for recognition of P82-101 or the carboxy terminal region of MBP, two regions thought to be important in the human T-cell response to the molecule. No relationship between the use of a particular DR allele and a response to a particular region of MBP could be established.(ABSTRACT TRUNCATED AT 250 WORDS)

The human T-cell receptor beta-chain repertoire: longitudinal fluctuations and assessment in MHC matched populations

The influence of the environment and of the major histocompatibility complex (MHC) in shaping the human T-cell receptor beta-chain variable region (TCRBV) repertoire has not been systematically studied. Here, expression of TCRBV gene families was estimated by a sensitive polymerase chain reaction (PCR)-based method. Serial studies of peripheral blood, performed at 2-week intervals over a 3-month period, revealed that fluctuation in the expression of many TCRBV genes occurred in healthy individuals and in the absence of clinically evident infections. Fluctuation of TCRBV4, TCRBV5.2, TCRBV9, and TCRBV13.1 genes were present in all subjects. Additional TCRBV genes fluctuated in some but not in other individuals. Comparison of the TCRBV repertoire between these unrelated individuals indicated differences in the mean expression of TCRBV5.1, TCRBV9, TCRBV11, TCRBV15, TCRBV17, and TCRBV20 genes. For any TCRBV gene, intersubject differences were generally of a magnitude of twofold or less. Larger differences characterized the TCRBV repertoire of CD4 compared to CD8 cells. Some differences, for example over-representation of TCRBV2 and TCRBV5.1 on CD4, and TCRBV10, TCRBV14, and TCRBV16 on CD8 cells, were present in most subjects. Individuals homozygous for DR2- or DR3-bearing extended MHC haplotypes displayed similar individual variability of TCRBV expression. These data indicate that the circulating TCRBV repertoire in humans is both dynamic and diverse. Both environment and MHC effects contribute to the diversity of TCRBV expression.

Inhibitory effect of maternal antibody on mother-to-child transmission of human T-lymphotropic virus type I. The Mother-to-Child Transmission Study Group

In order to evaluate the protective role of the maternal antibody against mother-to-child transmission of HTLV-I, we followed a total of 780 children born to HTLV-I carrier mothers by investigating the level of anti-HTLV-I antibody transferred in utero, decline of the maternal antibody and seroconversion in post-natal life. The anti-HTLV-I antibody was positively detected within the first 3-6 months of life and declined at 6-12 months after birth in all children. After the maternal antibody declined, seroconversion occurred in some of the children following either breast feeding or bottle feeding. The seroconversion rates of short-term (less than or equal to 6 months) and long-term (greater than or equal to 7 months) breast feeders were 4.4% (4/90 cases) and 14.4% (20/139 cases), and the rate of bottle feeders was 5.7% (9/158 cases). Long-term breast feeding yielded more seroconverters than short-term breast feeding; 14.4% (20/139 cases) vs. 4.4% (4/90 cases), RR = 3.68, p = 0.018. The seroconversion rate of short-term breast feeders was nearly equal to that of bottle feeders; 4.4% (4/90 cases) vs. 5.7% (9/158 cases), RR = 0.770, p = 0.471. When neonatal lymphocytes were cultured with breast milk cells of HTLV-I carrier mothers, the in vitro infection of HTLV-I was inhibited by the addition of HTLV-I-seropositive cord-blood plasma. Our results suggest that the maternal antibody may inhibit HTLV-I infection by short-term breast feeding but not by long-term breast feeding after decline of the maternal antibody.

Cytotoxic and suppressor activities in patients with HTLV-I-associated myelopathy

Since there are several immune abnormalities and autoimmune-like features in human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/HTLV-I-associated tropical spastic paraparesis (HAM/TSP), we examined cytotoxic and suppressor cell functions in HAM/TSP. In this study, we assayed cell-mediated cytotoxicity of CD8+ T-cell lines established from cerebrospinal fluid lymphocytes of two patients with HAM and concanavalin A-induced suppressor cell activities of peripheral blood lymphocytes from five patients with HAM. Our study revealed that three of four CD8+ T-cell lines showed cytotoxic activities against autologous CD4+ T-cell lines infected with HTLV-I, and two of the three lines showed major histocompatibility complex class I-restricted cytotoxicity. We also demonstrated that the concanavalin A-induced suppressor function was not defective in HAM patients. Therefore, the immune abnormalities and autoimmune-like features observed in HAM/TSP may not result from defective cytotoxic or suppressor cell activities.

Autoproliferative and self-reactive T-cell lines from patients with HTLV-I-associated myelopathy

In two patients with human T lymphotropic virus type 1 (HTLV-I)-associated myelopathy (HAM) and a non-HAM HTLV-I carrier, T-cell lines were generated and characterized from cerebrospinal fluid (CSF) lymphocytes and peripheral blood lymphocytes (PBL). In total, 62 T-cell lines were established using direct plating technique for expanding human T lymphocytes. Sixty three percent of the T-cell lines were CD4+, CDw29+ and HTLV-I gag+. CD8+T-cell lines were also established and they were gag-. Proliferation in the absence of additional antigens and exogenous interleukin 2 ("autoproliferation") was observed in 61% of the T-cell lines and significantly correlated with HTLV-I antigen (gag) expression. In addition, some T-cell lines from HAM patients exhibited proliferative response to self PBL, and the magnitude of their responses was diverse according to the phenotypes of stimulating cells. Therefore, the spontaneous lymphoproliferation observed in patients with HAM is generated by three components; HTLV-I-infected T cells and T cells reactive against HTLV-I and against self antigens. Since most gag+ T-cell lines produced lymphotoxin (LT)/tumor necrosis factor alpha (TNF alpha), it is suggested that those T cells are playing important roles in the pathogenesis of HAM.

Association of a particular amino acid sequence of the HLA-DR beta 1 chain with HTLV-I-associated myelopathy

Analyses of HLA-DRB1 gene using polymerase chain reaction and sequence-specific oligonucleotide probes reveal that the amino acid sequence Glu-Gln-Arg-Arg-Ala-Ala-Val at positions 69-75 of the third hypervariable region (HVR) of HLA-DR beta 1 chain is significantly associated with HTLV-I-associated myelopathy (HAM). Since the frequency of this sequence in HTLV-I carriers is almost the same as that in controls from Kagoshima (an endemic area of HTLV-I), this sequence may be related to susceptibility to HAM rather than to susceptibility to HTLV-I infection. Since this third HVR functions as putative antigen-binding sites and T cell recognition sites, the amino acid sequence of positions 68-73 was analyzed in detail. The analysis reveals that Gln70 and Arg71 are relevant to the occurrence of HAM.

[Oligoclonal IgG bands in patients with HTLV-I associated myelopathy--detection by agarose isoelectric focusing, transfer to cellulose nitrate and immunoperoxidase staining]

The patient with HTLV-I associated myelopathy (HAM) shows a quite uniform clinical picture characterized by slowly progressive spastic paraparesis, slight sensory disturbances and urinary frequency, and the pathogenetic relationship between spastic paraparesis and HTLV-I was established. Since then, the role of the virus in causing myelopathy has drawn increasing attention. However, we have little information about cerebrospinal fluid (CSF) abnormalities in patients with HAM. Analysis of CSF oligoclonal bands (OB) in 22 patients with HAM was reported. All of 22 patients had typical clinical signs and symptoms of HAM with high titers of anti-HTLV-I antibodies in the serum by particle agglutination method. And these antibodies against HTLV-I were confirmed by enzyme-linked immunosorbent assay and western blot. Detection or characterization of CSF OB was done by high resolution agarose gel (HARG) electrophoresis with silver staining and immunofixation method with immunostaining. Other method for detection OB was by agarose isoelectric focusing (IEF), transfer to cellulose nitrate and immunoperoxidase staining (Olsson, 1984). CSF OB was detected in 13 of 22 patients with HAM by the method of immunofixation, using HRAG. All of CSF OB reacted with peroxidase conjugated goat anti-human IgG serum. More than 3 oligoclonal bands were not detected in HRAG electrophoresis. However, CSF OB was detected in all of 22 patients by the method of Olsson (IEF, in agarose, double-antibody peroxidase labelling and avidin-biotin amplification). The majority of patients with HAM had at least 5 or more OB in the region between pH 6.8 and 9.5.(ABSTRACT TRUNCATED AT 250 WORDS)

HTLV-I-associated myelopathy and adult T-cell leukemia cases in a family

Familial cases of HTLV-I-associated myelopathy (HAM) and adult T-cell leukemia (ATL), developing in a daughter and father, respectively, are reported. The coexistence of both diseases in a family has not been reported before. This supports the recent findings that ATL and HAM may be brought about by an identical virus on an apparently different immunogenetic background.

HLA haplotype-linked high immune responsiveness against HTLV-I in HTLV-I-associated myelopathy: comparison with adult T-cell leukemia/lymphoma

HLA haplotypes of 27 patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) and 12 patients with adult T-cell leukemia/lymphoma (ATLL) were examined by analyzing HLA types of the patients and their family members. Either A11Bw54Cw1DR4DQw3, A24Bw54Cw1DR4DQ-, A24B7Cw7DR1DQw1, or A24Bw52Cw-DR2DQw1 and the related haplotypes were found in 70% of cases with HAM. None of these "HAM-associated" haplotypes was found in patients with ATLL. HLA haplotypes made up of HLA components of A26Bw62Cw3DR5DQw3 and one particular haplotype of Aw33B44Cw-DRw6DQw1 were associated with the ATLL haplotypes. These "ATLL-associated" haplotypes were also found in the patients with HAM who had no previous history of blood transfusion. The in vitro cultures of peripheral blood lymphocytes with HTLV-I virion antigens revealed that the response with HAM peripheral blood lymphocytes was remarkably higher than that with ATLL peripheral blood lymphocytes. Based on this HTLV-I-specific immune responsiveness, we can segregate the high responders in HAM (14 of 16 cases) and the low responders in ATLL (6 of 7 cases). The existence of high and low responders was also confirmed by the normal healthy individuals, whose responses were segregated with HAM-associated and ATLL-associated haplotypes. These results suggested that two ethnic groups in southern Kyushu may get the two different diseases, HAM and ATLL, because of their different immunogenetic backgrounds. The high immune response to HTLV-I seems to be an important genetic factor in the development of HAM.

Chronic progressive myelopathy associated with elevated antibodies to human T-lymphotropic virus type I and adult T-cell leukemialike cells

Six adult patients had a chronic progressive myelopathy that possessed the following features: high antibody titers to human T-lymphotropic virus type I (HTLV-I) in serum and cerebrospinal fluid (CSF); predominantly upper motor neuron disorder, symmetrical, with mild sensory and bladder disturbances; and presence of adult T-cell leukemia-like cells in both peripheral blood and CSF. We refer to this entity as HTLV-I-associated myelopathy (HAM). Electrophoretic studies of immunoglobulin G in CSF using Western blot analysis characteristically demonstrated p24 and p32 bands. Rates of intra-blood-brain barrier synthesis were determined and found increased in the patients with HAM. Corticosteroid treatment produced clinical improvement in all of 4 patients. A retrospective survey of CSF samples was carried out in 287 patients with neurological disorders, and 6 additional patients with HAM were identified.