Emilia L. Oleszak

Immunopathology of secondary-progressive multiple sclerosis

Twenty‐three plaques obtained at early autopsy from 2 patients with secondary‐progressive multiple sclerosis were examined immunohistochemically for microglia/macrophages, and for immunoglobulins and components of activated complement. Most of the lesions examined in both cases exhibited evidence of low‐grade active demyelination of an unusual type (frustrated phagocytosis) in periplaque white matter. This included linear groups of microglia engaging short segments of disrupted myelin that were associated with deposits of C3d, an opsonin formed during complement activation. Similar microglia/C3d/myelin profiles were not observed in newly forming lesions in cases of acute multiple sclerosis or other central white matter diseases. As C3d coupling is known to increase the immunogenicity of potential antigens enormously, present findings point to disrupted myelin close to plaques as a possible source of the putative multiple sclerosis antigen. Ongoing myelin destruction found in a high proportion of old, established plaques was surprising. It suggests that slowly expanding lesions (progressive plaques), in which ongoing myelin breakdown occurs in the absence of florid perivascular cell cuffing or other histological signs of acute inflammation, contribute to disease progression in cases of secondary‐progressive multiple sclerosis.

Theiler's Virus Infection: a Model for Multiple Sclerosis

SUMMARY Both genetic background and environmental factors, very probably viruses, appear to play a role in the etiology of multiple sclerosis (MS). Lessons from viral experimental models suggest that many different viruses may trigger inflammatory demyelinating diseases resembling MS. Theilers virus, a picornavirus, induces in susceptible strains of mice early acute disease resembling encephalomyelitis followed by late chronic demyelinating disease, which is one of the best, if not the best, animal model for MS. During early acute disease the virus replicates in gray matter of the central nervous system but is eliminated to very low titers 2 weeks postinfection. Late chronic demyelinating disease becomes clinically apparent approximately 2 weeks later and is characterized by extensive demyelinating lesions and mononuclear cell infiltrates, progressive spinal cord atrophy, and axonal loss. Myelin damage is immunologically mediated, but it is not clear whether it is due to molecular mimicry or epitope spreading. Cytokines, nitric oxide/reactive nitrogen species, and costimulatory molecules are involved in the pathogenesis of both diseases. Close similarities between Theilers virus-induced demyelinating disease in mice and MS in humans, include the following: major histocompatibility complex-dependent susceptibility; substantial similarities in neuropathology, including axonal damage and remyelination; and paucity of T-cell apoptosis in demyelinating disease. Both diseases are immunologically mediated. These common features emphasize the close similarities of Theilers virus-induced demyelinating disease in mice and MS in humans.

Apoptosis in chronic rejection of human cardiac allografts.

Background. We investigated the role of apoptosis (programed cell death) in the pathogenesis of chronic rejection. Methods. Epicardial coronary arteries from cardiac allografts with chronic rejection were examined for apoptosis by the TUNEL assay. Double labeling was carried out using anti-CD3, anti-CD68, and anti-von Willenbrand factor (vWF) monoclonal antibodies. Additional immunostaining was carried using anti-Fas, anti-Fas-L, and anti-Bcl-2 monoclonal antibodies. Apoptosis-associated oligonucleosomal DNA degradation was assessed by DNA agarose gel electrophoresis. The transcription level of apoptosis-related caspase genes were determined using microarrays. Results. Apoptotic cells (TUNEL+) were detected within the arterial wall and in perivascular areas. Double labeling demonstrated that apoptotic cells included T cells (CD3+), monocyte/macrophages (CD68+), and vascular endothelial cells (VWF+). Numbers and densities of TUNEL+ cells did not correlate with the degree of arterial stenosis. Apoptosis-associated oligonucleosomal DNA degradation was assessed by agarose gel electrophoresis of DNA, which showed DNA fragments of approximately 180 bp and multimers thereof (DNA laddering gel), which are characteristic for DNA fragmentation in apoptotic cells. Microarray analysis demonstrated that the apoptosis related caspases 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, were all transcribed (caspases 8, 9, and 10 were highly up-regulated). These results are consistent with the involvement of apoptosis in chronic rejection. Immunoreactivity for Fas/Fas-L was present at the sites of apoptotic cells. Immunoreactivity for Bcl-2 was present in areas with very few apoptotic cells. Conclusions. Apoptotic cells include T cells, monocyte/macrophages, and endothelial cells. Apoptosis, likely through the Fas/Fas-L system, is involved in the pathogenesis of chronic rejection in cardiac allografts.

Presence of Oligoclonal T Cells in Cerebrospinal Fluid of a Child with Multiphasic Disseminated Encephalomyelitis following Hepatitis A Virus Infection

ABSTRACT We have investigated the clonality of β-chain T-cell receptor (TCR) transcripts from the cerebrospinal fluid (CSF) and peripheral blood from a 7-year old child who developed a multiphasic disseminated encephalomyelitis following an infection with hepatitis A virus. We amplified β-chain TCR transcripts by nonpalindromic adaptor (NPA)-PCR–Vβ-specific PCR. TCR transcripts from only five Vβ families (Vβ13, Vβ3, Vβ17, Vβ8, and Vβ20) were detected in CSF. The amplified products were combined, cloned, and sequenced. Sequence analysis revealed in the CSF substantial proportions of identical β-chain of TCR transcripts, demonstrating oligoclonal populations of T cells. Seventeen of 35 (48%) transcripts were 100% identical, demonstrating a major Vβ13.3 Dβ2.1 Jβ1.3 clonal expansion. Six of 35 (17%) transcripts were also 100% identical, revealing a second Vβ13 clonal expansion (Vβ13.1 Dβ2.1 Jβ1.2). Clonal expansions were also found within the Vβ3 family (transcript Vβ3.1 Dβ2.1 Jβ1.5 accounted for 5 of 35 transcripts [14%]) and within the Vβ20 family (transcript Vβ20.1 Dβ1.1 Jβ2.4 accounted for 3 of 35 transcripts [8%]). These results demonstrate the presence of T-cell oligoclonal expansions in the CSF of this patient following infection with hepatitis A virus. Analysis of the CDR3 motifs revealed that two of the clonally expanded T-cell clones exhibited substantial homology to myelin basic protein-reactive T-cell clones. In contrast, all Vβ TCR families were expressed in peripheral blood lymphocytes. Oligoclonal expansions of T cells were not detected in the peripheral blood of this patient. It remains to be determined whether these clonally expanded T cells are specific for hepatitis A viral antigen(s) or host central nervous system antigen(s) and whether molecular mimicry between hepatitis A viral protein and a host protein is responsible for demyelinating disease in this patient.

Abdominal Aortic Aneurysm Is a Specific Antigen‐Driven T Cell Disease

Abstract:  To determine whether monoclonal/oligoclonal T cells are present in abdominal aortic aneurysm (AAA) lesions, we amplified β‐chain T cell receptor (TCR) transcripts from these lesions by the nonpalindromic adaptor (NPA)‐polymerase chain reaction (PCR)/V‐β‐specific PCR followed by cloning and sequencing. Sequence analysis revealed the presence of substantial proportions of identical β‐chain TCR transcripts in AAA lesions in 9 of 10 patients examined, strongly suggesting the presence of oligoclonal populations of αβ TCR+ T cells. We have also shown the presence of oligoclonal populations of γδ TCR+ T cells in AAA lesions. Sequence analysis after appropriate PCR amplification and cloning revealed the presence of substantial proportions of identical VγI and VγII TCR transcripts in 15 of 15 patients examined, and of Vδ1 and Vδ2 TCR transcripts in 12 of 12 patients. These clonal expansions were very strong. All these clonal expansions were statistically significant by the binomial distribution. In other studies, we determined that mononuclear cells infiltrating AAA lesions express early‐ (CD69), intermediate‐ (CD25, CD38), and late‐ (CD45RO, HLA class II) activation antigens. These findings suggest that active ongoing inflammation is present in the aortic wall of patients with AAA. These results demonstrate that oligoclonal αβ TCR+ and γδ TCR+T cells are present in AAA lesions. These oligoclonal T cells have been clonally expanded in vivo in response to yet unidentified antigens. Although the antigenic specificity of these T cells remains to be determined, these T cells may play a significant role in the initiation and/or the propagation of the AAA. It appears that AAA is a specific antigen‐driven T cell disease.

Immunology of Theiler's murine encephalomyelitis virus infection.

Theiler’s murine encephalomyelitis virus (TMEV) is a single-stranded RNA virus that belongs to the family of picornaviruses. Intracranial inoculation of susceptible mouse strains with TMEV results in biphasic disease, consisting of early acute disease that resembles poliomyelitis, followed by late chronic demyelinating disease that is characterized by the appearance of chronic inflammatory demyelinating lesions. Susceptibility to TMEV infection is genetically controlled by three loci: one that maps to the H-2D region of the major histocompatibility complex, one to the beta-chain constant region of the T-cell antigen receptor, and one located on chromosome 3. Both early acute and chronic late demyelinating diseases are immunologically mediated. T cells appear to play an important role in the pathogenesis of the disease. TMEV-induced demyelinating disease in mice has extensive similarities with multiple sclerosis, and it is considered one of the best experimental animal models for multiple sclerosis.

Aneurysmal Lesions of Patients with Abdominal Aortic Aneurysm Contain Clonally Expanded T Cells

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1–2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified β-chain TCR transcripts by the nonpalindromic adaptor–PCR/Vβ-specific PCR and/or Vβ-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of β-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that αβ TCR+ T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag–driven T cell disease.

Apoptosis of infiltrating T cells in the central nervous system of mice infected with Theiler's murine encephalomyelitis virus

Theiler murine encephalomyelitis virus (TMEV), DA strain, induces in susceptible strain of mice a biphasic disease consisting of early acute disease followed by late chronic demyelinating disease. Both phases of the disease are associated with inflammatory infiltrates of the central nervous system (CNS). Late chronic demyelinating disease induced by TMEV serves as an excellent model to study human demyelinating disease, multiple sclerosis. During early acute disease, the virus is partially cleared from the CNS by CD3(+) T cells. These T cells express Fas, FasL, negligible levels of Bcl-2 proteins and undergo activation-induced cell death as determined by TUNEL assay leading to resolution of the inflammatory response. In contrast, during late chronic demyelinating disease, and despite dense perivascular and leptomeningeal infiltrates, only very few cells undergo apoptosis. Mononuclear cells infiltrating the CNS express Bcl-2. It appears that the lack of apoptosis of T cells during late chronic demyelinating disease leads to the accumulation of these cells in the CNS. These cells may play a role in the pathogenesis of the demyelinating disease.

Oligoclonal T cells are infiltrating the brains of children with AIDS: sequence analysis reveals high proportions of identical β-chain T-cell receptor transcripts

We have recently described the presence of perivascular CD3+ CD45RO+ T cells infiltrating the brains of children with AIDS. To determine whether these infiltrates contain oligoclonal populations of T cells, we amplified by PCR β‐chain T‐cell receptor (TCR) transcripts from autopsy brains of four paediatric patients with AIDS. The amplified transcripts were cloned and sequenced. Sequence analysis of the β‐chain TCR transcripts from all four patients revealed multiple identical copies of TCR β‐chain transcripts, suggesting the presence of oligoclonal populations of T‐cells. These TCR transcripts were novel. The presence of oligoclonal populations of T cells in the brains of these four paediatric patients with AIDS suggests that these T cells have undergone antigen‐driven proliferation and clonal expansion very likely in situ, in the brains of these AIDS patients, in response to viral or self‐antigens. Although the specificity of the clonally expanded β‐chain TCR transcripts remains to be elucidated, none of the β‐chain TCR transcripts identified in this study were identical to those specific for HIV‐1 antigens that are currently reported in the GENBANK/EMBL databases. Certain common CDR3 motifs were observed in brain‐infiltrating T cells within and between certain patients. Large proportions (24 of 61; 39%) of β‐chain TCR clones from one patient (NP95‐73) and 2 of 27 (7%) of another patient (NP95‐184‐O) exhibited substantial CDR3 homology to myelin basic protein (MBP)‐specific TCR derived from normal donors or TCR expressed in the brain of patients with multiple sclerosis (MS) or with viral encephalitis. These two patients (NP95‐73 and NP95‐184‐O) also shared HLA class II with the normal donors and the MS patients who expressed these homologous TCR. Pathologic examination at autopsy of the brains revealed the presence of myelin pallor only in patient NP95‐73. T‐cell clones identified in the brain of patients NP95‐73 and NP95‐184‐O may recognize MBP or another CNS self antigen and this recognition may be restricted by either DRB1*15 or DQB1*0602 specificities.

Hybridoma-derived human suppressor factors: Inhibition of growth of tumor cell lines and effect on cytotoxic cells

With the objective of developing human T-T cell hybrids producing B-cell growth factor, we fused concanavalin A-activated T lymphocytes with cells of the Jurkat T cell line. The hybrids were selected on the basis of their ability to form colonies in soft agar, whereas the parent Jurkat T cell line did not. T-T cell hybrids were HLA-typed, screened by functional tests, and recloned by limiting dilution. In addition to obtaining B-cell growth factor-producing hybrids, we also obtained certain other T-T cell hybrids (as determined by HLA-typing) producing suppressor factors inhibiting proliferative responses and antibody production by human lymphocytes. Subsequently, a suppressor factor with similar inhibitory properties was identified in supernatants of the Jurkat T cell line. However, the Jurkat factor exhibited different biochemical and functional properties than the hybridoma-derived suppressor factors. Using two-parameter cell cycle analysis and the metachromatic fluorochrome acridine orange, we found that the hybridoma-derived 160 and 169 suppressor factors arrested phytohemagglutinin-induced proliferative of peripheral blood mononuclear cells in the G0/G1 phase of the cell cycle, whereas the Jurkat suppressor factor arrested proliferation in the S phase. Incubation of peripheral blood mononuclear cells with the 160, 169, or Jurkat suppressor factors for 24 hr at 37 degrees C, followed by washing, did not alter their cell cycle progression (or RNA content) in response to stimulation with phytohemagglutinin. The hybridoma-derived 160 and 169 suppressor factors and the Jurkat factor inhibited the growth but not the viability of cells from the following human tumor cell lines: A673 sarcoma cell line, SK-LC-6 and SK-LC-14 lung cell lines, SB, Raji, and Daudi lymphoblastoid cell lines, and FARR malignant melanoma cell line. In contrast, it did not affect the growth of murine L1210 cells and FS-4 normal human diploid fibroblasts. The hybridoma-derived 160 suppressor factor was selected to investigate its effect on cell-mediated cytotoxicity. The 160 suppressor factor did not inhibit natural killer cytotoxicity or its augmentation by interferon alpha or interleukin 2 or the generation of lymphokine-activated killer cells. However, this factor partially inhibited the generation of specific T cell-mediated cytotoxicity.