scholarly journals Detection of hyperreactive T cells in multiple myeloma by multivalent cross-linking of the CD3/TCR complex [see comments]

Blood ◽  
1991 ◽  
Vol 78 (7) ◽  
pp. 1770-1780 ◽  
Author(s):  
M Massaia ◽  
A Bianchi ◽  
C Attisano ◽  
S Peola ◽  
V Redoglia ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Normal Subjects ◽  
Cross Linking ◽  
Peripheral Blood Mononuclear ◽  
Hla Dr ◽  
Lower Ratio

Abstract Cellular immunity was investigated in 43 patients with multiple myeloma (MM) by assessing 3HTdR uptake induced by monocyte-dependent [CD3 monoclonal antibodies (MoAbs), phytohemagglutinin (PHA)] and monocyte- independent (CD2 MoAbs, ionomycin + phorbolester) stimulations. The former were evaluated in peripheral blood mononuclear cells (PBMNC) and purified T cells; the latter were evaluated in purified T-cell preparations only. MM showed significantly lower PBMNC responses to PHA (P less than .001), soluble OKT3 (CD3) (P = .01), and immobilized OKT3 MoAbs (P = .01). On purification of T cells, MM responses were still defective to soluble T11(2) + T11(3) (CD2) MoAbs (P = .004), phorbol myristate acetate (PMA) plus ionomycin (P less than .001), but significantly higher to plastic-immobilized OKT3 (P = .004). In some MM, 3HTdR uptake, interleukin-2 (IL-2) receptor (CD25) expression, and IL-2 production were as high on stimulation with plastic-immobilized OKT3 as that observed in normal subjects under optimal conditions (ie, plastic-immobilized OKT3 plus accessory signals). CD3 hyperreactivity correlated with the number of CD8+ HLA-DR+ cells in MM T-cell preparations. MM patients with more than 10% CD8+ HLA-DR+ cells had significantly higher responses to immobilized OKT3 (P less than .001), but lower responses to T11(2) plus T11(3) (P = .01), and PMA plus ionomycin (P = .03) than patients with less than 10% CD8+ HLA-DR+ cells. Phenotyping of CD45RA (naive) and CD45R0 (memory) expressions in resting MM T cells showed a lower ratio of CD45RA to CD45R0 in both CD4 (P less than .05) and CD8 (P less than .001) subpopulations. These data indicate that (a) some MM T cells require significantly fewer accessory signals (if any) to express the IL-2 receptor fully, secrete IL-2, and proliferate on multivalent cross-linking of the CD3/TCR complex; and (b) this peculiar state of activation is associated with high HLA-DR expression in CD8+ lymphocytes.

scholarly journals Detection of hyperreactive T cells in multiple myeloma by multivalent cross-linking of the CD3/TCR complex [see comments]

Blood ◽  
1991 ◽  
Vol 78 (7) ◽  
pp. 1770-1780 ◽  
Author(s):  
M Massaia ◽  
A Bianchi ◽  
C Attisano ◽  
S Peola ◽  
V Redoglia ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Normal Subjects ◽  
Cross Linking ◽  
Peripheral Blood Mononuclear ◽  
Hla Dr ◽  
Lower Ratio

Cellular immunity was investigated in 43 patients with multiple myeloma (MM) by assessing 3HTdR uptake induced by monocyte-dependent [CD3 monoclonal antibodies (MoAbs), phytohemagglutinin (PHA)] and monocyte- independent (CD2 MoAbs, ionomycin + phorbolester) stimulations. The former were evaluated in peripheral blood mononuclear cells (PBMNC) and purified T cells; the latter were evaluated in purified T-cell preparations only. MM showed significantly lower PBMNC responses to PHA (P less than .001), soluble OKT3 (CD3) (P = .01), and immobilized OKT3 MoAbs (P = .01). On purification of T cells, MM responses were still defective to soluble T11(2) + T11(3) (CD2) MoAbs (P = .004), phorbol myristate acetate (PMA) plus ionomycin (P less than .001), but significantly higher to plastic-immobilized OKT3 (P = .004). In some MM, 3HTdR uptake, interleukin-2 (IL-2) receptor (CD25) expression, and IL-2 production were as high on stimulation with plastic-immobilized OKT3 as that observed in normal subjects under optimal conditions (ie, plastic-immobilized OKT3 plus accessory signals). CD3 hyperreactivity correlated with the number of CD8+ HLA-DR+ cells in MM T-cell preparations. MM patients with more than 10% CD8+ HLA-DR+ cells had significantly higher responses to immobilized OKT3 (P less than .001), but lower responses to T11(2) plus T11(3) (P = .01), and PMA plus ionomycin (P = .03) than patients with less than 10% CD8+ HLA-DR+ cells. Phenotyping of CD45RA (naive) and CD45R0 (memory) expressions in resting MM T cells showed a lower ratio of CD45RA to CD45R0 in both CD4 (P less than .05) and CD8 (P less than .001) subpopulations. These data indicate that (a) some MM T cells require significantly fewer accessory signals (if any) to express the IL-2 receptor fully, secrete IL-2, and proliferate on multivalent cross-linking of the CD3/TCR complex; and (b) this peculiar state of activation is associated with high HLA-DR expression in CD8+ lymphocytes.

scholarly journals Inhibition of CD4 cross-linking-induced lymphocytes apoptosis by vesnarinone as a novel immunomodulating agent: vesnarinone inhibits Fas expression and apoptosis by blocking cytokine secretion

Blood ◽  
1996 ◽  
Vol 87 (6) ◽  
pp. 2361-2368 ◽  
Author(s):  
N Oyaizu ◽  
TW McCloskey ◽  
S Than ◽  
S Pahwa
Keyword(s):  
T Cells ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Cytokine Secretion ◽  
Tnf Alpha ◽  
Cross Linking ◽  
Apoptosis Induction ◽  
Peripheral Blood Mononuclear ◽  
Cell Surface Molecule ◽  
Ifn Gamma

Evidence is accumulating that T cells from human immunodeficiency virus type 1 (HIV-1)-infected individuals show accelerated cell death through apoptosis. We have recently demonstrated that the cross-linking of CD4 molecules (CD4XL) results in death of normal peripheral T cells through apoptosis and imbalanced cytokine secretion (ie, induction of tumor necrosis factor-alpha [TNF-alpha] and interferon-gamma [IFN-gamma] in the absence of interleukin-2 [IL-2] or IL-4 secretion). These upregulated cytokines (TNF-alpha/IFN-gamma) largely contributed to upregulation of the apoptosis-inducing cell surface molecule, Fas (APO- 1/CD95) and apoptosis induction. The present study investigated the effect of vesnarinone as a novel immunomodulating agent on CD4XL- induced T-cell apoptosis. The addition of vesnarinone to peripheral blood mononuclear cells (PBMC) significantly inhibited CD4XL-induced lymphocyte apoptosis. This apoptosis-inhibitory effect of vesnarinone was associated with the blocking of CD4XL-induced TNF-alpha IFN-gamma secretion and of Fas antigen upregulation. However, vesnarinone did not block effects of exogenously supplemented TNF-alpha/IFN-gamma on Fas induction. These data suggest that vesnarinone inhibits CD4XL-induced TNF-alpha/IFN-gamma secretion, thereby blocking subsequent Fas upregulation and apoptosis induction. Given the potent pathogenic role of imbalanced cytokine secretion observed in HIV-infection, an agent such as vesnarinone may be of therapeutic value in slowing disease progression.

scholarly journals Daclizumab reduces CD25 levels on T cells through monocyte-mediated trogocytosis

2013 ◽  
Vol 20 (2) ◽  
pp. 156-164 ◽  
Author(s):  
Y Zhang ◽  
M McClellan ◽  
L Efros ◽  
D Shi ◽  
B Bielekova ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Treg Cells ◽  
Activated T Cells ◽  
Peripheral Blood Mononuclear ◽  
Dependent Relationship ◽  
Cell Counts ◽  
Humanized Monoclonal Antibody

Daclizumab is a humanized monoclonal antibody that prevents interleukin-2 (IL-2) binding to CD25, blocking IL-2 signaling by cells that require high-affinity IL-2 receptors to mediate IL-2 signaling. The phase 2a CHOICE study evaluating daclizumab as a treatment for multiple sclerosis (MS) included longitudinal analysis of activated T cell counts. Whereas an exposure-dependent relationship was observed between daclizumab and reductions in HLA-DR+-activated T cells, a similar relationship was not observed for reductions in CD25 levels. The objective of this report is to determine the mechanism by which daclizumab reduces CD25 levels on peripheral blood mononuclear cells (PBMCs) using cytometric techniques. Daclizumab reduced T cell CD25 levels through a mechanism that required the daclizumab-Fc domain interaction with Fc receptors (FcR) on monocytes, but not on natural killer (NK) cells, and was unrelated to internalization or cell killing. Activated CD4+ T cells and FoxP3+ Treg cells showed evidence of trogocytosis of the CD25 antigen in the presence of monocytes. A daclizumab variant that retained affinity for CD25 but lacked FcR binding did not induce trogocytosis and was significantly less potent as an inhibitor of IL-2-induced proliferation of PBMCs. In conclusion, Daclizumab-induced monocyte-mediated trogocytosis of CD25 from T cells appears to be an additional mechanism contributing to daclizumab inhibition of IL-2 signaling.

scholarly journals Interleukin-2 production and response to interleukin-2 by peripheral blood mononuclear cells from patients after bone marrow transplantation: II. Patients receiving soybean lectin-separated and T cell-depleted bone marrow

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1595-1603 ◽  
Author(s):  
K Welte ◽  
CA Keever ◽  
J Levick ◽  
MA Bonilla ◽  
VJ Merluzzi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells

Abstract The ability of peripheral blood mononuclear cells (PBMC) to produce and respond to interleukin-2 (IL-2) was evaluated in 50 recipients of HLA- identical bone marrow (BM) depleted of mature T cells by soybean agglutination and E rosetting (SBA-E-BM). In contrast to our previous findings in recipients of unfractionated marrow, during weeks 3 to 7 post-SBA-E-BM transplantation (BMT), PBMC from the majority of patients spontaneously released IL-2 into the culture medium. This IL-2 was not produced by Leu-11+ natural killer cells, which were found to be predominant in the circulation at this time, but by T11+, T3+, Ia antigen-bearing T cells. The IL-2 production could be enhanced by coculture with host PBMC frozen before transplant but not by stimulation with mitogenic amounts of OKT3 antibody, thus suggesting an in vivo activation of donor T cells or their precursors by host tissue. Spontaneous IL-2 production was inversely proportional to the number of circulating peripheral blood lymphocytes and ceased after 7 to 8 weeks post-SBA-E-BMT in most of the patients. In patients whose cells had ceased to produce IL-2 spontaneously or never produced this cytokine, neither coculture with host cells nor stimulation with OKT3 antibody thereafter induced IL-2 release through the first year posttransplant. Proliferative responses to exogenous IL-2 after stimulation with OKT3 antibody remained abnormal for up to 6 months post-SBA-E-BMT, unlike the responses of PBMC from recipients of conventional BM, which responded normally by 1 month post-BMT. However, the upregulation of IL- 2 receptor expression by exogenous IL-2 was found to be comparable to normal controls when tested as early as 3 weeks post-SBA-E-BMT. Therefore, the immunologic recovery of proliferative responses to IL-2 and the appearance of cells regulating in vivo activation of T cells appear to be more delayed in patients receiving T cell-depleted BMT. Similar to patients receiving conventional BMT, however, the ability to produce IL-2 after mitogenic stimulation remains depressed for up to 1 year after transplantation.

scholarly journals Accelerated apoptosis in peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus type-1 infected patients and in CD4 cross-linked PBMCs from normal individuals

Blood ◽  
1993 ◽  
Vol 82 (11) ◽  
pp. 3392-3400 ◽  
Author(s):  
N Oyaizu ◽  
TW McCloskey ◽  
M Coronesi ◽  
N Chirmule ◽  
VS Kalyanaraman ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Mononuclear Cells ◽  
Cross Linking ◽  
Peripheral Blood Mononuclear ◽  
Immunodeficiency Virus ◽  
Blood Mononuclear Cells ◽  
Hiv 1

This study investigates apoptosis as a mechanism for CD4+ T-cell depletion in human immunodeficiency virus type-1 (HIV-1) infection. Although several recent studies have shown that T cells of HIV-infected individuals show enhanced susceptibility to cell death by apoptosis, the mechanisms responsible for apoptosis are largely unknown. By using a flow cytometric technique and by morphology, we have quantitated the percentage of cells undergoing apoptosis in peripheral blood mononuclear cells (PBMCs) from HIV-seronegative donors and from HIV- infected asymptomatic patients. The PBMCs were cultured without any stimulus or with staphylococcus enterotoxin B, anti-T-cell receptor (TCR) alpha beta monoclonal antibody WT-31, or phytohemagglutinin for periods up to 6 days. In addition, we sought to determine whether cross- linking of CD4 followed by various modes of TCR stimulation in vitro could induce apoptosis in normal PBMCs. Here we show that (1) patient PMBCs undergo marked spontaneous apoptosis; (2) stimulation of T cells of patients as well as normal donors results in increased apoptosis; and (3) cross-linking of CD4 molecules is sufficient to induce apoptosis in CD4+ T cells if cross-linking is performed in unfractioned PBMCs, but not if CD4 molecules are cross-linked in purified T-cell preparations. These observations strongly suggest that accelerated cell death through apoptosis plays an important role in the pathogenesis of HIV-1 infection. At the same time, our observations implicate cross- linking of CD4 in vivo as a major contributor to this mechanism of accelerated cell death in HIV infection.

scholarly journals Interleukin-2 production and response to interleukin-2 by peripheral blood mononuclear cells from patients after bone marrow transplantation: II. Patients receiving soybean lectin-separated and T cell-depleted bone marrow

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1595-1603 ◽  
Author(s):  
K Welte ◽  
CA Keever ◽  
J Levick ◽  
MA Bonilla ◽  
VJ Merluzzi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Peripheral Blood Mononuclear Cells ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Interleukin 2 ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells

The ability of peripheral blood mononuclear cells (PBMC) to produce and respond to interleukin-2 (IL-2) was evaluated in 50 recipients of HLA- identical bone marrow (BM) depleted of mature T cells by soybean agglutination and E rosetting (SBA-E-BM). In contrast to our previous findings in recipients of unfractionated marrow, during weeks 3 to 7 post-SBA-E-BM transplantation (BMT), PBMC from the majority of patients spontaneously released IL-2 into the culture medium. This IL-2 was not produced by Leu-11+ natural killer cells, which were found to be predominant in the circulation at this time, but by T11+, T3+, Ia antigen-bearing T cells. The IL-2 production could be enhanced by coculture with host PBMC frozen before transplant but not by stimulation with mitogenic amounts of OKT3 antibody, thus suggesting an in vivo activation of donor T cells or their precursors by host tissue. Spontaneous IL-2 production was inversely proportional to the number of circulating peripheral blood lymphocytes and ceased after 7 to 8 weeks post-SBA-E-BMT in most of the patients. In patients whose cells had ceased to produce IL-2 spontaneously or never produced this cytokine, neither coculture with host cells nor stimulation with OKT3 antibody thereafter induced IL-2 release through the first year posttransplant. Proliferative responses to exogenous IL-2 after stimulation with OKT3 antibody remained abnormal for up to 6 months post-SBA-E-BMT, unlike the responses of PBMC from recipients of conventional BM, which responded normally by 1 month post-BMT. However, the upregulation of IL- 2 receptor expression by exogenous IL-2 was found to be comparable to normal controls when tested as early as 3 weeks post-SBA-E-BMT. Therefore, the immunologic recovery of proliferative responses to IL-2 and the appearance of cells regulating in vivo activation of T cells appear to be more delayed in patients receiving T cell-depleted BMT. Similar to patients receiving conventional BMT, however, the ability to produce IL-2 after mitogenic stimulation remains depressed for up to 1 year after transplantation.

T cells support osteoclastogenesis in an in vitro model derived from human multiple myeloma bone disease: the role of the OPG/TRAIL interaction

Blood ◽  
2004 ◽  
Vol 104 (12) ◽  
pp. 3722-3730 ◽  
Author(s):  
Silvia Colucci ◽  
Giacomina Brunetti ◽  
Rita Rizzi ◽  
Antonia Zonno ◽  
Giorgio Mori ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Bone Disease ◽  
Mononuclear Cells ◽  
Death Receptor ◽  
B Cell Lymphoma ◽  
Nuclear Factor Κb ◽  
Peripheral Blood Mononuclear

The development of multiple myeloma (MM) bone disease is mediated by increased number and activity of osteoclasts (OCs). Using an in vitro osteoclastogenesis model consisting of unstimulated and unfractionated peripheral blood mononuclear cells (PBMCs) from patients with MM, we showed that T cells support the formation of OCs with longer survival. Different from T-cell–depleted MM PBMC cultures, exogenous macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL) were necessary for the formation of OCs; however, they did not exhibit longer survival. We found up-regulated production of RANKL, osteoprotegerin (OPG), and TNF-related apoptosis-inducing ligand (TRAIL) by fresh MM T cells. Despite high OPG levels, the persistence of osteoclastogenesis can be related to the formation of the OPG/TRAIL complex demonstrated by immunoprecipitation experiments and the addition of anti-TRAIL antibody which decreases OC formation. OCs overexpressed TRAIL decoy receptor DcR2 in the presence of MM T cells and death receptor DR4 in T-cell–depleted cultures. In addition, increased Bcl-2/Bax (B-cell lymphoma-2/Bcl2-associated protein X) ratio, following Bcl-2 up-regulation, was detected in OCs generated in the presence of T cells. Our results highlight that MM T cells support OC formation and survival, possibly involving OPG/TRAIL interaction and unbalanced OC expression of TRAIL death and decoy receptors.

scholarly journals Accelerated apoptosis in peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus type-1 infected patients and in CD4 cross-linked PBMCs from normal individuals

Blood ◽  
1993 ◽  
Vol 82 (11) ◽  
pp. 3392-3400 ◽  
Author(s):  
N Oyaizu ◽  
TW McCloskey ◽  
M Coronesi ◽  
N Chirmule ◽  
VS Kalyanaraman ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Mononuclear Cells ◽  
Cross Linking ◽  
Peripheral Blood Mononuclear ◽  
Immunodeficiency Virus ◽  
Blood Mononuclear Cells ◽  
Hiv 1

Abstract This study investigates apoptosis as a mechanism for CD4+ T-cell depletion in human immunodeficiency virus type-1 (HIV-1) infection. Although several recent studies have shown that T cells of HIV-infected individuals show enhanced susceptibility to cell death by apoptosis, the mechanisms responsible for apoptosis are largely unknown. By using a flow cytometric technique and by morphology, we have quantitated the percentage of cells undergoing apoptosis in peripheral blood mononuclear cells (PBMCs) from HIV-seronegative donors and from HIV- infected asymptomatic patients. The PBMCs were cultured without any stimulus or with staphylococcus enterotoxin B, anti-T-cell receptor (TCR) alpha beta monoclonal antibody WT-31, or phytohemagglutinin for periods up to 6 days. In addition, we sought to determine whether cross- linking of CD4 followed by various modes of TCR stimulation in vitro could induce apoptosis in normal PBMCs. Here we show that (1) patient PMBCs undergo marked spontaneous apoptosis; (2) stimulation of T cells of patients as well as normal donors results in increased apoptosis; and (3) cross-linking of CD4 molecules is sufficient to induce apoptosis in CD4+ T cells if cross-linking is performed in unfractioned PBMCs, but not if CD4 molecules are cross-linked in purified T-cell preparations. These observations strongly suggest that accelerated cell death through apoptosis plays an important role in the pathogenesis of HIV-1 infection. At the same time, our observations implicate cross- linking of CD4 in vivo as a major contributor to this mechanism of accelerated cell death in HIV infection.

scholarly journals BCR/ABL leukemia oncogene fusion peptides selectively bind to certain HLA-DR alleles and can be recognized by T cells found at low frequency in the repertoire of normal donors

Blood ◽  
1996 ◽  
Vol 88 (6) ◽  
pp. 2118-2124 ◽  
Author(s):  
G Pawelec ◽  
H Max ◽  
T Halder ◽  
O Bruserud ◽  
A Merl ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Low Frequency ◽  
Myelogenous Leukemia ◽  
Fusion Peptides ◽  
Cell Repertoire ◽  
Peripheral Blood Mononuclear ◽  
Hla Dr

Chronic myelogenous leukemia (CML) is characterized by the t(9;22) translocation that results in chimeric genes encoding bcr/abl fusion proteins. Junction-spanning sequences represent unique tumor-specific moieties that might be exploited therapeutically. We investigate here the binding of synthetic bcr/abl peptides to various HLA-DR alleles and their recognition by T cells from normal donors and CML patients. A 23- mer b3/a2 peptide bound very strongly to isolated HLA-DRB1*1101 (Dw5) and relatively strongly to DRB1*0301 (Dw3) and DRB1*0402 (Dw10) molecules, as estimated using a competition assay. It failed to bind to several other DR alleles, including three different DR4 alleles. In contrast, a 23-mer b2/a2 peptide bound only to the DRB1*0301 (Dw3) allele. Peripheral blood mononuclear cells from normal donors were sensitized in vitro against the b3/a2 peptide. After four repetitive stimulations, T cells responding to the peptide were found at low frequency in 5 of the 11 donors tested. Three of the five were HLA- DR11+, and all three of the DR11+ donors tested were found to respond. T cells recognizing bcr/abl peptides were not identified in any of the CML patients studied, regardless of HLA type. Finally, even peptide- reactive T-cell lines from normal donors were not stimulated by native CML cells in the absence of exogenous peptide. These results show the presence of low-frequency major histocompatability complex class II- restricted bcr/abl-responses in the normal T-cell repertoire of donors with certain HLA types, but suggest that unmodified tumor cells cannot be recognized by such peptide-sensitized T cells.

Class I–unrestricted noncytotoxic anti–HTLV-I activity of CD8+ T cells

Blood ◽  
2000 ◽  
Vol 96 (5) ◽  
pp. 1994-1995 ◽  
Author(s):  
Masako Moriuchi ◽  
Hiroyuki Moriuchi
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Membrane Filter ◽  
Cd8 T Cell ◽  
Class I ◽  
Type I ◽  
Peripheral Blood Mononuclear ◽  
Permeable Membrane

Abstract Although it is widely believed that viral clearance is mediated principally by the destruction of infected cells by cytotoxic T cells, noncytolytic antiviral activity of CD8+ T cells may play a role in preventing the progression to disease in infections with immunodeficiency viruses and hepatitis B virus. We demonstrate here that (1) replication of human T-lymphotropic virus type I (HTLV-I) is more readily detected from CD8+ T-cell–depleted (CD8−) peripheral blood mononuclear cells (PBMCs) of healthy HTLV-I carriers than from unfractionated PBMCs, (2) cocultures of CD8− PBMCs with autologous or allogeneic CD8+ T cells suppressed HTLV-I replication, and (3) CD8+ T-cell anti-HTLV-I activity is not abrogated intrans-well cultures in which CD8+ cells are separated from CD8− PBMCs by a permeable membrane filter. These results suggest that class I-unrestricted noncytolytic anti–HTLV-I activity is mediated, at least in part by a soluble factor(s), and may play a role in the pathogenesis of HTLV-I infection.

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