Yasuto Itoyama

Spontaneous proliferation of peripheral blood lymphocytes increased in patients with HTLV‐I‐associated myelopathy

We found unstimulated (spontaneous) peripheral blood lymphocyte (PBL) proliferation significantly increased in 14 patients with human T-lymphotropic virus (HTLV)-I-associated myelopathy (HAM) compared with findings in HTLV-I seropositive non-HAM carriers (N = 8) or HTLV-I seronegative controls (N = 16). The proliferative response to phytohemagglutinin, concanavalin A, or pokeweed mitogen was decreased in the HAM patients. Cell clusters were frequent in cultures of unstimulated PBL from the HAM patients, but much less common in the controls or carriers. This spontaneous PBL proliferation was depressed when adherent-cell populations were depleted from the cultures. IL-2 activity increased in the supernatant of 3-day cultured cells from HAM patients, but not in cultured cells from the controls. Since IL-2 receptor positive cells increased in HAM, this spontaneous PBL proliferation is probably a response to IL-2 through the expression of IL-2 receptors.

Leukoencephalopathy in HTLV-I-associated myelopathy/tropical spastic paraparesis: MRI analysis and a two year follow-up study after corticosteroid therapy

Magnetic resonance imaging (MRI) of the brain was studied in 35 patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP), 19 HTLV-I seropositive carriers without HAM/TSP (non-HAM/TSP carriers), 18 patients with HTLV-I seronegative spastic spinal paraparesis (SSP), and 82 HTLV-I seronegative controls with other neurological disorders. The incidence of white matter lesions was significantly higher in HAM/TSP (66%) than in the controls (23%) and SSP (11%). HAM/TSP exceeded non-HAM/TSP carriers significantly in the incidence of multiple white matter lesions (37% vs 10%). HAM/TSP affected the deep and subcortical cerebral white matter multifocally, sparing the periventricular regions. None of the lesions were enhanced by gadolinium-DTPA. HAM/TSP patients with the white matter lesions had both a longer duration of disease and a greater disability than did those without lesions. The white matter lesions gradually increased in number, as the disability status became worse, in spite of the high dose corticosteroid treatment. All these observations suggest that the MRI abnormalities of the HAM/TSP brain may reflect the chronic perivascular inflammation with progressive gliosis (chronic disseminated encephalomyelitis). We propose that brain MRI can be successfully utilized as a reliable and non-invasive measure for following the disease progression in HAM/TSP.

Antibody titers to HTLV-I-p40tax protein and gag-env hybrid protein in HTLV-I-associated myelopathy/tropical spastic paraparesis: correlation with increased HTLV-I proviral DNA load.

We studied the relationship between antibody titers to recombinant HTLV-I p40tax protein and gag-env hybrid protein in serum (by an enzyme-linked immunosorbent assay) and HTLV-I proviral DNA load in peripheral blood mononuclear cells (by a quantitative polymerase chain reaction method) in 18 patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP), 17 HTLV-I carriers without HAM/TSP and 16 HTLV-I uninfected controls. The IgG and IgA antibody titers to either of the proteins correlated significantly with the HTLV-I pX (coding p40tax protein) and pol DNA amounts in HTLV-I infected subjects. HAM/TSP patients had significantly higher titers of IgG and IgA antibodies to the HTLV-I proteins than did the HTLV-I carriers without HAM/TSP. While the IgM antibodies to the HTLV-I proteins were found in only 6% of HTLV-I carriers without HAM/TSP, they were found in 40% of HAM/TSP patients, especially those having both a high HTLV-I proviral DNA load and high titers of the IgG and IgA antibodies. HAM/TSP patients with the IgM antibodies had a tendency to deteriorate more frequently on the Kurtzkes disability status scale and magnetic resonance imaging of the brain (leukoencephalopathy) than did those without in the two-year follow-up. Thus, the presence of IgM antibody and high titers of IgG and IgA antibodies to the HTLV-I proteins, together with the increased HTLV-I proviral DNA load, appears to distinguish HAM/TSP patients from HTLV-I carriers without HAM/TSP.

Altered subsets of peripheral blood lymphocytes in patients with HTLV‐I associated myelopathy (HAM)

We studied subsets of peripheral blood lymphocytes (PBL) from 12 patients with human T-lymphotropic virus type I (HTLV-I) associated myelopathy (HAM). The percent of OKT8+ cells was significantly decreased, and the percentages of OKDR+ cells and IL-2R+ cells and the ratio of OKT4+ cells to OKT8+ cells were significantly increased compared with either HTLV-I seronegative healthy adults (controls) or HTLV-I seropositive non-HAM subjects (carriers). The subsets of PBL from eight carriers showed no differences from those in controls. The patients with HAM showed significantly higher antibody titers to HTLV-I compared with carriers. These altered PBL subsets and high HTLV-I antibody titers in the patients suggest that immune functions are in an activated state in HAM.

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.

P2 Protein in Oligodendrocytes and Myelin of the Rabbit Central Nervous System

Abstract: P2 protein, a myelin‐specific protein, was detected immunocyto‐chemically and biochemically in rabbit central nervous system (CNS) myelin. P2 protein was synthesized by rabbit oligodendrocytes and was present in varying amounts throughout the rabbit CNS. Comparison of P2 and myelin basic protein (MBP) stained sections revealed that P2 antiserum did not stain all myelin sheaths within the rabbit CNS. The proportion of myelin sheaths stained by P2 antiserum and the amount of P2 detected biochemically were greater in more caudal regions of the rabbit CNS. The highest concentration of P2 protein was found in rabbit spinal cord myelin, where P2 antiserum stained the majority of myelin sheaths. P2 protein was barely detectable biochemically in myelin isolated from frontal cortex, and in sections of frontal cortex only occasional myelin sheaths reacted with P2 antiserum. These results suggest that the regional variations in the amount of P2 protein are due to regional differences in the number of myelin sheaths that contain P2 protein. P2 protein was detected immunocytochemically and biochemically in rabbit sciatic nerve myelin. Immunocytochemically, P2 antiserum only stained a portion of the myelin sheaths present. The myelin sheaths not reacting with P2 antiserum had small diameters and represented less than 10% of the total myelinated fibers.

Leukoencephalopathy in HTLV-I-associated myelopathy: MRI and EEG data

Magnetic resonance imaging (MRI) of the brain and electroencephalography (EEG) were carried out for patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM). Nineteen of 22 patients (86%) had abnormalities on brain MRI and/or EEG. Thirteen patients showed high signal intensity lesions scattered in the cerebral white matter, as seen on the T2-weighted MRI images. The lesions were mostly located in the subcortical and deep cerebral white matter and were not contiguous with the lateral ventricles. Patients with abnormalities on the brain MRI had a longer duration of disease and a greater disability than did those without MRI abnormalities. The EEG records showed definite abnormalities in 9, and minor abnormalities in 5. All patients with HAM for more than 5 years showed definite evidence of cerebral involvement. Our findings strongly suggest that a multifocal pathological process over the entire CNS is probably a common occurrence in HAM.

Experimental allergic encephalomyelitis in the Lewis rat ☆: A model of predictable relapse by cyclophosphamide

Relapse of experimental allergic encephalomyelitis (EAE) was achieved in Lewis rats by cyclophosphamide (CY). All rats, immunized with an emulsion of guinea pig spinal cord homogenate in complete Freunds adjuvant and treated with 100 mg/kg of CY 21 days postimmunization (pi), developed moderate to severe paralysis 9-14 days following CY injection. A second relapse was observed in 4 of 11 rats reinjected with CY 49 days pi. Histologically, focal mononuclear cell infiltration with or without demyelination of the white matter of the central nervous system was observed. Cyclophosphamide administration caused transient leukopenia and T-cell defect, the resolution of which coincided with relapse of clinical EAE. Lymphocyte proliferative responses to myelin basic protein (BP) and concanavalin A (Con A) and antibody titers to BP were preserved in CY-treated rats. Adoptive transfer of EAE to naive recipients with Con A-activated spleen cells from donors with CY-induced relapse was unsuccessful.

Early loss of astrocytes in herpes simplex virus–induced central nervous system demyelination

Immunohistochemistry was used to study herpes simplex virus type 1–induced central nervous system demyelination in the trigminal root entry zone of mice inoculated with herpes simplex virus type 1 by the corneal route. There was no change in peripheral nervous system myelin as shown by immunostaining for Po glycoprotein. Double immunoperoxidase staining for herpes simplex virus type 1 antigens and glial fibrillary acidic protein showed that most of the infected cells were astrocytes. Glial fibrillary acidic protein immunostaining was completely lost in the inferior medial portion of the trigeminal root entry zone at 6 days after herpes simplex virus type 1 inoculation, a time when central nervous system myelin was preserved as indicated by immunostaining for myelin basic protein. The pattern of glial fibrillary acidic protein staining did not change and herpes simplex virus type 1 antigens were no longer detected after day 8. There was a progressive loss of myelin basic protein staining within the area unstained by glial fibrillary acidic protein antisera on days 8 to 14. This pattern of astrocyte loss before central nervous system demyelination is strikingly different from the reactive astrocytosis seen in other demyelinating lesions, such as acute experimental allergic encephalomyelitis, progressive multifocal leukoencephalopathy, or acute multiple sclerosis. Herpes simplex virus type 1 infection in mice provides an unusual model of acute central nervous system demyelination preceded by a loss of astrocytes.

Cellular immune surveillance against HTLV-I infected T lymphocytes in HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP)

To investigate the cellular immune surveillance against HTLV-I infected T lymphocytes in HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP), we studied the cytotoxic T lymphocytes (CTL) activity against an HTLV-I infected human T cell line (MT-2) and the natural killer (NK) cell activity in 15 HAM patients, 6 HTLV-I carriers, and 15 controls. The activity of CTL against MT-2 cells was found to be significantly elevated in HAM compared with that in the controls. This cytotoxicity in HAM was higher than in HTLV-I carriers, although the difference was not statistically significant. There was an HLA class I restriction in this CTL activity against MT-2 cells in HAM. On the other hand, NK cell activity was significantly lower in HAM than in controls. Cold target inhibition studies suggested that NK cells could not lyse MT-2 cells effectively. There was a positive correlation between the CTL activity against MT-2 cells and the serum antibody titers to HTLV-I in HAM.