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.     

Enhanced adherence of endothelial cells to blood mononuclear cells in HAM/TSP]

We investigated the adhesion of blood mononuclear cells (MNC) isolated from patients with HTLV-1-associated myelopathy (HAM/TSP). MNC from HAM/TSP patients were significantly more adherent to activated endothelial monolayers than MNC from non-HAM/TSP (controls and HTLV-1 carriers) subjects. Blocking studies demonstrated that the adhesion molecules VLA-4 (CD49d), ICAM-1 (CD54), and L-selectin (CD62L) all contributed to increased binding. However, anti-ICAM-1 antibody was the most efficient in inhibiting binding HAM/TSP patients MNC to activated endothelial cells. Expression on MNC of molecules involved in adhesion was also studied by flow cytometry in HAM/TSP patients, HTLV-1 carriers, and healthy control subjects after two days culture without any mitogen. In HAM/TSP patients, L-selectin expression on CD4+ and CD8+ subsets was lower than in controls; interestingly, HAM/TSP patients had lower percentage of CD4+ subset expressing L-selectin than HTLV-1 carriers. The percentage of CD4+ and CD8+ cells expressing VLA-4 was found to be similar to controls in both HAM/TSP patients and HTLV-1 carriers. Following two days in culture without mitogen, the percentage of T cells expressing ICAM-1 increased in HAM/TSP and carriers, but not in controls. This study provides information regarding trans-endothelial migration of MNC across the blood brain barrier in HAM/TSP and suggests ICAM-1 and its counterpart molecule LAF-1 are involved in massive infiltration of lymphocytes observed in the spinal cord.     

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.     

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.     

HTLV-I specific IFN-gamma+ CD8+ lymphocytes correlate with the proviral load in peripheral blood of infected individuals

Human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is an inflammatory neurological disease caused by HTLV-I infection. It has been shown that HAM/TSP patients have high proviral loads and an extraordinarily high frequency of circulating CD8 + cytotoxic T lymphocytes specific for HTLV-I in their peripheral blood when compared to asymptomatic HTLV-I carriers (AC). We have previously described an intracellular cytokine detection assay, in which interferon-gamma (IFN-gamma) + CD8 + lymphocytes are specific for HTLV-I in infected individuals. Here, we have established a competitive polymerase chain reaction assay to measure the proviral load of patients and investigate a potential relationship between proviral load and virus-specific CD8 + lymphocytes. Genomic DNA was extracted from peripheral blood lymphocytes (PBL) from eight HAM/TSP patients and seven AC for the measurement of HTLV-I measuring proviral loads. The same PBL were analyzed for intracellular IFN-gamma expression by flow cytometry. In the HAM/TSP patients and AC, the average proviral loads were 34,482 and 9784 copy/microg DNA (P = 0.021), and the average of IFN-gamma + CD8 + lymphocytes in total PBL were 1.47 and 0.08% (P = 0.001), respectively. It was confirmed that HAM/TSP patients have both high proviral loads and increased HTLV-I-specific CD8 + lymphocytes. Furthermore, we found a positive correlation between both factors in the patients with HAM/TSP (P = 0.044) but not in the AC (P = 0.508). These findings suggest that the high number of HTLV-I-specific lymphocytes may result from the increased proviral load in HAM/TSP patients.     

Flow cytometry evaluation of the T-cell receptor Vbeta repertoire among human T-cell lymphotropic virus type-1 (HTLV-1) infected individuals: effect of interferon alpha therapy in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is chronic inflammatory disease of the spinal cord characterized by perivascular lymphocytic cuffing and parenchymal lymphocytic infiltration. In this study using flow cytometry, we have investigated the T-cell receptor (TCR) Vbeta repertoire of peripheral blood T lymphocytes in 8 HAM/TSP patients, 10 HTLV-1 infected healthy carriers, and 11 uninfected healthy controls to determine if there is a biased usage of TCR Vbeta. We found that TCR Vbeta7.2 was under-utilized and Vbeta12 was over-utilized in CD4+ T cells of HTLV-1 infected individuals compared with healthy uninfected controls, whereas there were no such differences in CD8+ T cells. Comparison of Vbeta repertoire changes before and after interferon-alpha (IFN-alpha) treatment for HAM/TSP revealed that one out of five patients showed dramatic decrease of specific Vbeta in CD8+ T cells. Our results suggest that dominant Vbeta subpopulations in CD4+ T cells evolved associated with chronic HTLV-1 infection, and IFN-alpha treatment for HAM/TSP does not induce a specific pattern of TCR Vbeta changes.     

Cell surface phenotype of in vitro proliferating lymphocytes in HTLV-I-associated myelopathy (HAM/TSP)

The in vitro proliferation of peripheral blood lymphocytes (PBLs) without any mitogenic stimulation is one of the hallmarks of human T lymphotropic virus type I (HTLV-I) infection. Recent evidence suggests a difference in the degree of the phenomenon between HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and asymptomatic HTLV-I carriers (AC). In this article, we demonstrated several alterations in the features of the in vitro transformed lymphocytes between patients with HAM/TSP (n = 16) and AC (n = 8). The percentages of total CD8+ and CD8+CD28+ cells were significantly increased in the in vitro proliferating T lymphocytes derived from the patients with HAM/TSP when compared to those from AC. HAM/TSP was segregated from AC by the high degree of the proliferation of CD8+CD28+ cells. The expression of HTLV-I-specific antigens on the cultured PBLs was detected only in the subjects which showed low CD8+CD28+/CD4+ ratio of the in vitro proliferating lymphocytes. These findings suggest that this phenomenon distinguishes HAM/TSP from AC, not only in quantity but also in quality.     

Elevated levels of interleukin-12 and interferon-gamma in patients with human T lymphotropic virus type I-associated myelopathy

The levels of interleukin-12 (IL-12) (p70 heterodimer), total IL-12 (p70 heterodimer plus p40 chains), interferon-gamma (IFN-gamma) as Th1 cytokine, and those of interleukin-4 (IL-4) and interleukin-10 (IL-10) as Th2 cytokines in sera and cerebrospinal fluid (CSF) from 22 patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) were compared with those of 22 patients with other neurological diseases (OND), including nine anti-HTLV-I-seropositive carriers. Both serum IL-12 (total and p70 heterodimer) and CSF IFN-gamma, measured by the enzyme-linked immunosorbent assay (ELISA), were significantly elevated in patients with HAM as compared to the patients with OND, including the anti-HTLV-I-seropositive carriers. Serum IFN-gamma also was significantly elevated in the HAM patients as compared to the controls. There was no significant difference in the CSF levels of IL-12 (total and p70 heterodimer) between the HAM patients and controls, whereas, for the Th2 cytokines IL-4 was detected in the CSF of four anti-HTLV-I-seropositive carriers of the 13 control patients but not in any of the patients with HAM. No significant difference was found in the serum levels of IL-4 and IL-10, nor in the CSF levels of IL-10 in the patients with HAM and in the controls. These findings indicate that in patients with HAM, the immunological balance of helper T lymphocytes between Th1 and Th2 is toward Th1 in the periphery and that Th1-mediated immunological status in the central nervous system is involved in the pathogenesis of HAM.     

Selective matrix metalloproteinase inhibitor,N-biphenyl sulfonyl phenylalanine hydroxamic acid,inhibits the migration of CD4+ T lymphocytes in patients with HTLV-I-associated myelopathy

Matrix metalloproteinases (MMPs) have been reported to be involved in various inflammatory disorders. Previous studies revealed that MMP-2 and MMP-9 might play important roles in the breakdown of the blood-brain barrier (BBB) in the central nervous system (CNS) of patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). N-Biphenyl sulfonyl-phenylalanine hydroxamic acid (BPHA) selectively inhibits MMP-2, -9 and -14, but not MMP-1, -3 and -7. In the present study, we examined whether or not the selective MMP inhibitor BPHA could inhibit the heightened migrating activity of CD4+ T cells in HAM/TSP patients. The migration assay using an invasion chamber showed that migration of CD4+ T cells in HAM/TSP patients was inhibited by 25 microM BPHA. In addition, the inhibitory ratio of migrating CD4+ lymphocytes was higher in HAM patients compared to normal controls. These results suggest that the selective MMP inhibitor BPHA has therapeutic potential for HAM/TSP.     

DPB 1 *0501-associated opticomyelitis and atopic myelitis: novel disease entities]

To clarify the relationship between Th 1/Th 2 balance and clinical features, we studied the intracellular IFN gamma-positive versus IL-4-positive cell ratio in peripheral blood CD 4 T cells by flow cytometry and measured total and allergen-specific IgE by ELISA in 227 patients with various neurologic diseases including multiple sclerosis (MS), myelitis and HAM/TSP, and 42 healthy hospital subjects. The intracellular IFN gamma/IL-4 ratio in the patients with acute myelitis was significantly decreased, and the total serum IgE level and frequency of mite antigen-specific IgE were significantly elevated as compared with the controls. Patients with HAM/TSP, however, had a significantly higher intracellular IFN gamma/IL-4 ratio, lower total IgE level, and lower frequency of cedar pollen-specific IgE than did the controls. The patients with recurrent opticomyelitis (ROM) had a significantly higher frequency of relapse, higher EDSS score, and lower number of brain MRI lesions than the patients with conventional MS, and only those with ROM showed a significant association with the HLA-DPB 1 *0501 allele. The ROM patients had a significantly higher intracellular IFN gamma/IL-4 ratio and IL-4-/IFN-gamma + cell percentages than the controls. These findings suggest that the Th 2 cell response predominates in acute myelitis with hyperIgEaemia (atopic myelitis), whereas the Th 1 cell response predominates in ROM and HAM/TSP.     

Flow cytometric differentiation of Asian and Western types of multiple sclerosis, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and hyperIgEaemic myelitis by analyses of memory CD4 positive T cell subsets and NK cell subsets

We examined the alterations of memory CD4(+) T cell subsets bearing surface receptors linked to either Th1 or Th2 cytokine production as well as natural killer (NK) cell subsets by three color flow cytometry in the peripheral blood from 36 patients with clinically definite multiple sclerosis (MS), 27 patients with HAM/TSP, 13 patients with hyperIgEaemic myelitis who had mite antigen-specific IgE and 25 healthy controls (HC). The patients with MS were clinically classified into an optico-spinal form of MS (Asian type, MS-A) and the conventional form of MS (Western type, MS-W). MS-A showed a significant increase of CD4(+)CD45RA(-)CCR5(+) cells (Th1 cells) through the relapse and remission phases in comparison to HC, while MS-W showed a significant increase of CD4(+)CD45RO(+)CD62L(-) cells (Th1 cells) only at the relapse phase. HAM/TSP showed a significant increase of CCR5(+) and CD62L(-) memory CD4(+) T cells as well as CD30(+) memory CD4(+) T cells (Th2 cells) in comparison to HC. On the other hand, a selective increase of CD4(+)CD45RO(+)CD30(+) cells was found in hyperIgEaemic myelitis. The percentage of mature NK cells (CD3(-)CD16(+)CD56(+) cells) as well as double negative T cells (CD3(+)CD4(-)CD8(-) cells) decreased significantly in HAM/TSP in comparison to HC. Our findings therefore suggest a flow cytometric analysis of Th1/Th2-associated markers on memory CD4(+) T cells as well as NK cell subsets to be useful for differentiating various inflammatory neurologic conditions.     

High production of RANTES and MIP-1alpha in the tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM)

Human T cell lymphotropic virus type 1 (HTLV-1) infection is associated with progressive neurological disorders and tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). The pathogenesis of TSP/HAM is considered as immune mediated, involving cytotoxic T cell (CTL) responses to a number of viral proteins and notably the regulation protein Tax. T CD8+ cells produce beta-chemokines, which are important in the anti-viral response. In the present study, we have analyzed the CC chemokines (RANTES, MIP-1beta and MIP-1alpha) production in retrovirus-infected subjects. A total of 191 subjects were studied: 52 healthy controls, 72 asymptomatic HTLV-1-infected carriers and 67 TSP/HAM patients. Peripheral blood mononuclear cells were maintained in the presence or absence of PHA, and supernatant fluids were assayed using EIA. MIP-1beta concentration was not significantly different across groups, but RANTES and MIP-1alpha concentrations showed significant differences when the three groups were compared. In TSP/HAM patients, the increase in the production of chemokines may lead to a recruitment of pro-inflammatory factors, contributing to the membrane's myelin damage.     

Therapeutic effect of lymphocytapheresis on patients with HTLV-I-associated myelopathy (HAM)]

Lymphocytapheresis (LCP) was performed in 7 patients (1 male and 6 females) with HAM to delete lymphocytes from their peripheral blood, resulting in an improvement of motor disability in 6 of 7 patients with HAM. The therapeutic effect appeared within one day after first LCP, and reached maximum in 2 or 3 sessions of LCP. The side effects were only dysesthesia in 5 patients during LCP and mild leukopenia in a patient after LCP. Both of them were mild and transient. The effect of LCP continued for two to five months in 6 patients, the remaining one deteriorated in a month. In the study of T cell subsets of peripheral blood lymphocytes by flowcytometry, the CD4/8 ratio and the cell counts of CD4+ DR+, CD8+ DR+ and IL-2R positive cells were gradually decreased by LCP. These results suggest that LCP is one of the effective therapies for HAM and peripheral blood lymphocytes implicate in the pathogenesis of HAM.     

HTLV-I alters the multidrug resistance associated protein 1 (ABCC1/MRP1) expression and activity in human T cells

The human T cell lymphotropic/leukaemia virus type I (HTLV-I) causes HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The multidrug resistance associated protein 1 (ABCC1) plays multiple functions in physiopathologic responses. The expression and activity of ABCC1 was studied in T lymphocytes from uninfected and HTLV-I-infected individuals (both asymptomatic and symptomatic/HAM/TSP). ABCC1 expression and activity was reduced to nearly half in T lymphocytes from infected patients compared to control lymphocytes. Only 51.6% of CD4(+) cells from HAM/TSP patients expressed ABCC1 whereas this was seen in 60.3% from asymptomatic individuals, compared to an expression of around 86% in controls. Our results suggest that ABCC1 is negatively regulated in HTVL-I infection, supplying a novel target to investigate the pathogenesis of HTLV-I.     

Neuropathology of human T lymphotropic virus type I-associated myelopathy

In order to clarify pathogenesis of human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) a detailed neuropathological analysis of eight autopsy patients with HAM/TSP was performed. Inflammatory infiltrates of mononuclear cells and degeneration of myelin and axons were noted in the middle to lower thoracic spinal cords and were extended continuously to the entire spinal cord. Horizontal distribution of inflammatory lesions was symmetric at any spinal levels. Immunohistochemical analysis demonstrated T cell dominance. The numbers of CD4+ T cells and CD8+ T cells were present in equal numbers in patients with shorter clinical course. Apoptosis of helper/inducer T cells were observed in the presence of TIA1+ cytotoxic T cells in these active inflammatory lesions. Inflammatory infiltrates were markedly decreased and CD8+/TIA1- T cells were predominated over CD4+ cells in patients with prolonged clinical course. HTLV-I proviral deoxyribonucleic acid (DNA) amounts in the freshly frozen spinal cord measured by quantitative polymerase chain reaction (PCR) were well correlated with the numbers of infiltrated CD4+ cells. In situ PCR of HTLV-I provial DNA using multi-primar pairs demonstrated the presence of HTLV-I infected cells exclusively in the mononuclear infiltrates of perivascular areas. From these findings, it is suggested that the target of the inflammatory process seen in HAM/TSP lesions may be HTLV-I infected CD4+ T cells infiltrating the spinal cord.     

Reduced Foxp3 expression with increased cytomegalovirus-specific CTL in HTLV-I-associated myelopathy

Human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients show high immune responses to HTLV-I. However, it is unclear whether the cytotoxic T lymphocyte (CTL) responses to other chronic viruses also increase. We investigated the responses in the peripheral blood by using HLA-A*0201/peptide pentamers. The frequency of cytomegalovirus (CMV)-specific CTL tended to be higher in HAM/TSP patients than in healthy controls (HCs). The frequency of CMV-specific CTL positively correlated with that of HTLV-I Tax-specific CTL. The frequency of Foxp3+ cells in CD4+ lymphocytes tended to be higher in HAM/TSP patients than in ACs and HCs. The expression level of Foxp3 was lower in HAM/TSP patients than in HCs and was inversely correlated with the CMV-specific CTL frequency. A percentage of Foxp3+ cells showed a positive correlation with the HTLV-I proviral load. These results suggest that a decrease in the Foxp3 expression may contribute to the high immune response to CMV and that the Foxp3+ regulatory T cells may play a role in the immune surveillance of HTLV-I.     

Natural killer (NK) cells in HTLV-I-associated myelopathy/tropical spastic paraparesis-decrease in NK cell subset populations and activity in HTLV-I seropositive individuals

We examined natural killer (NK) cell activity and NK cell subset populations in 18 patients with HTLV-I associated myelopathy (HAM)/tropical spastic paraparesis (TSP), ten HTLV-I seropositive asymptomatic carriers and 20 seronegative healthy controls. The NK cell activity was significantly decreased in HAM/TSP, compared with that in controls. The percentages of NK cell subsets, such as CD16+, CD11b+, CD56+, CD16+ CD56-, CD16-CD56+, CD16+CD8-, or CD16+CD3+ cells were significantly decreased in HAM/TSP patients. Of particular interest is that the percentage of CD16+CD3+ cells, which have a wide spectrum of cytotoxic properties commonly seen in NK, lymphokine activated killer (LAK) and antibody-dependent cellular-cytotoxic (ADCC) effector cells, was significantly decreased in HAM/TSP as compared to asymptomatic carriers as well as controls. The percentage of CD16+CD3+ cells correlated inversely with the value of spontaneous proliferation of peripheral blood lymphocytes (SPP), which is a characteristic change observed in HAM/TSP.     

Characterization of humoral and cellular immunity in the central nervous system of HAM/TSP

In HTLV-I-associated myelopathy or tropical spastic paraparesis (HAM/TSP) immunopathological processes in the central nervous system (CNS) have not been clarified. We compared the humoral and cellular immunity within the CNS and in the systemic circulation of 24 patients with HAM/TSP (8 men and 16 women) to 6 asymptomatic HTLV-I carriers, 7 patients with active multiple sclerosis, 6 patients with acute viral encephalitis, and 39 patients with other non-inflammatory neurological diseases. Significant differences were observed between the HAM/TSP patients and one or more of the control groups: HAM/TSP cerebrospinal fluids (CSF) exhibited higher levels of IgG, IgG index, de novo IgG synthesis rate, and β₂-microglobulin, and also a predominance of CD8⁺ cells that expressed CD11a and CD45RO but lacked CD28 antigens. Results in the 6 patients with acute viral encephalitis suggested that the CD8⁺ population in the CSF which is positive for CD28 and CD45RO is important for the elimination of virus from infected CNS tissues. Therefore, potentially cytotoxic T cells of a unique CD8⁺ CD11a⁺CD45RO⁺CD28⁻ phenotype may play a key role in the CNS pathogenesis of HAM/TSP.     

Increased frequency of CD4+T cells expressing fractalkine receptor CX3CR1 in patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), but its AIDS susceptible polymorphisms are not associated with the disease

To investigate whether fractalkine receptor CX3CR1 polymorphisms that have been associated with rapid progression to AIDS among HIV-1 positive individuals also affects the risk of human T cell lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP), we compared the allele frequencies of V249I and T280M between 233 HAM/TSP patients and 213 HTLV-1 seropositive asymptomatic carriers (HCs). Although the frequency and absolute number of peripheral blood CX3CR1+CD4+T cells were significantly increased in HAM/TSP patients compared to HCs and uninfected controls independent of HTLV-1 trans-activator protein Tax, we could not observe any association between the two polymorphisms and the risk of HAM/TSP in our cohort.     

Increased sialyl Lewis(x) antigen-positive cells mediated by HTLV-1 infection in peripheral blood CD4(+) T lymphocytes in patients with HTLV-1-associated myelopathy

Sialyl Lewis(x) antigen-positive (sLe(x+)) cells play an important role in the first step of transmigration of T lymphocytes through vascular endothelial cells into tissues. We compared the proportion of sLe(x+) cells in peripheral blood CD4(+) T lymphocytes between patients with HTLV-1-associated myelopathy (HAM) and control patients, by using flow cytometry. The percentage of sLe(x+) cells in peripheral blood CD4(+) T lymphocytes was significantly higher in HAM patients compared to control patients. Interferon-gamma (IFN-gamma), but not interleukin-4 (IL-4), production by the sLe(x+) cell population of peripheral blood CD4(+) T lymphocytes was significantly higher in HAM patients than in control patients. In addition, comparison of the HTLV-1 proviral load between sLe(x+) and sLe(x-) cells in peripheral blood CD4(+) T lymphocytes of HAM patients showed that the HTLV-1 proviral load was significantly higher (two- to eight-fold), concomitant with enhanced IFN-gamma production, in the sLe(x+) than in the sLe(x-) cell population. Our findings indicate that the sLe(x+) cell population, which has features of activated Th1 cells with up-regulated expression of E- and P-selectin ligands mediated by HTLV-1 infection, is increased in peripheral blood CD4(+) T lymphocytes in HAM patients, suggesting their involvement in transmigration of peripheral T lymphocytes from the peripheral blood into tissues.