Dale E. McFarlin

Transthyretin Pro55, a variant associated with early-onset, aggressive, diffuse amyloidosis with cardiac and neurologic involvement

SummaryMutations in the protein transthyretin cause amyloidosis involving the heart, peripheral nerves, and other organs. A family from West Virginia developed an unusually aggressive form of widespread transthyretin amyloidosis. Single-strand conformation polymorphism analysis revealed a variant in the transthyretin gene, which was found on sequencing to be a T→C transversion at position 2 of codon 55, corresponding to a Leu→ Pro substitution. The variant sequence was confirmed by restriction analysis and polymerase chain reaction (PCR)-primer introduced restriction analysis.

The germline repertoire of T cell receptor β-chain genes in patients with chronic progressive multiple sclerosis

The T cell receptor (TcR) beta-chain germline gene repertoire of multiple sclerosis (MS) patients was compared to that of 100 normal individuals. No differences in the number of gene segments defined by probes representing 14 different human V beta subfamilies and the constant region genes were found. The distribution of haplotypes defined by restriction fragment length polymorphism (RFLP) alleles detected with V beta 8, V beta 11, and C beta probes in the MS patients was significantly different from that found in normal individuals. Because 84% of the MS patients were DR2+, the findings in these patients were compared to a second group of 43 normals who were DR2+. The distribution of TcR haplotypes in MS patients was also significantly different from that in the DR2+ normals. The data suggest that an MS susceptibility gene(s) may be located in the region of the TcR beta-chain gene complex.

Cytokine-regulated adhesion between encephalitogenic T lymphocytes and cerebrovascular endothelial cells

Adhesive interactions between murine cerebrovascular endothelial cells (EC) which comprise the blood-brain barrier (BBB) and myelin basic protein (MBP)-specific encephalitogenic T lymphocytes were investigated. Adhesion was assessed by measuring the percent attachment of 51Cr-labeled T cells to EC monolayers. The basal level adhesion (20-35%) was significantly up-regulated by treating EC with recombinant murine gamma interferon (IFN-gamma), interleukin-1 alpha (IL-1 alpha) and/or tumor necrosis factor-alpha (TNF alpha). The ability of these cytokines to modulate adhesion was dose- and time-dependent and could be detected as early as 1 h after treatment. The expression of intercellular adhesion molecule-1 (ICAM-1) by EC was examined by immunofluorescence staining and ELISA. Although all unstimulated EC cultures expressed ICAM-1, treatment of EC with the above cytokines dramatically up-regulated the level of ICAM-1 expression in a dose- and time-dependent fashion similar to that observed in the adhesion assays. Treatment of EC with transforming growth factor-beta 1 (TGF beta) down-regulated the level of T cell adhesion on untreated EC in a dose-dependent manner. Pretreatment of EC with TGF beta also partially inhibited the up-regulation of adhesion induced by IFN-gamma, IL-1 alpha and/or TNF alpha. TGF beta had no effect on the up-regulation of ICAM-1 expression induced by IFN-gamma, IL-1 alpha and/or TNF alpha. These results indicate that in addition to ICAM-1, other molecules may be involved in adhesion of encephalitogenic T cells to the EC comprising the cerebral vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in T cell antigen specificity and class II restriction during the course of chronic relapsing experimental allergic encephalomyelitis

In order to assess T cell antigen specificities and class II restriction requirements during the course of chronic relapsing experimental allergic encephalomyelitis (CREAE), (SJL x PL)F1 mice were used as a model. EAE can be passively transferred in these mice by F1 T cells incubated with Ia-positive antigen-presenting cells (APC) from either parent SJL (H-2s) or PL (H-2u) and MBP fragments 89-169 or 1-37, respectively. T cells purified from F1 mice immunized with MBP fragment 1-37 were positively selected for I-Au-supported proliferation by culture in the presence of irradiated Iau-positive PL spleen cells as APC. I-As-supported proliferation and proliferation to residues 89-169 were not detected following selection. Adoptive transfer of this T cell line induced CREAE in naive recipient F1 mice and 2 weeks after the second attack of EAE recipient proliferative responses were measured. Recipient T cells proliferated to both fragment 1-37 and fragment 89-169. Moreover, proliferation was supported by I-As-positive as well as I-Au-positive macrophages. These findings demonstrate that T cells with novel epitope specificities and class II restriction requirements can be generated during the course of CREAE and suggest the possibility that such cells may be involved in the pathogenesis of this chronic autoimmune illness.

An unusual form of diabetes mellitus in ataxia telangiectasia.

Abstract Five of eight patients with documented ataxia telangiectasia had an unusual form of diabetes mellitus, characterized by marked hyperglycemia, resistance to ketosis, absence of glycosuria and markedly elevated plasma insulin levels in response to the administration of glucose or tolbutamide. Moreover, the blood glucose response to both exogenous and endogenous insulin was decreased, signifying insulin resistance similar to that found in pregnancy, acromegaly and obesity. In addition, the five subjects with diabetes had evidence of hepatic disease, which has not previously been reported in ataxia telangiectasia. Although the etiology of the hepatic dysfunction is not known, the immunologic deficiency commonly present in this disease may be responsible. Carbohydrate intolerance and the hypersecretion of insulin have been attributed to hepatic disease in some patients, or to certain lesions of the central nervous system in others, but it is not known if the diabetic state in ataxia telangiectasia res...

Susceptibility for multiple sclerosis is determined, in part, by inheritance of a 175-kb region of the TcR Vβ chain locus and HLA class II genes

Genetic makeup thought to affect susceptibility to multiple sclerosis (MS) and current evidence suggests that multiple genes may be involved. We have mapped a potential susceptibility gene or genes in the germ-line T cell receptor (TcR) V beta region of multiple sclerosis (MS) patients. Six restriction fragment length polymorphisms (RFLPs) spanning approximately 600 kb of the TcR V beta region were used to define TcR haplotypes in 197 Caucasian controls and 83 Caucasian MS patients in the chronic progressive stage of the disease. The distribution of TcR subhaplotype frequencies was significantly different only in the approx. 175-kb region between RFLPs defined by V beta 8.1 and V beta 11. Stratification of the MS patients into HLA-DR2+ (n = 51) and HLA-DR2- (n = 32) populations demonstrated that the subhaplotype frequencies differed from the control population significantly only in the HLA-DR2+ (corrected P = 0.00007) and not in the HLA-Dr2- (corrected P = 0.46) population. Subhaplotypes which are rare in the normal population are overrepresented in the HLA-DR2+ MS patient population and confer a relative risk of 4.06. These results indicate the existence of an MS susceptibility gene within the TcR V beta region, and provide new evidence for gene complementation between a HLA class II gene and TcR V beta gene(s) in conferring susceptibility to MS.

Multiple sclerosis in twins

We studied 30 sets of twins in whom one or both was suspected of having multiple sclerosis (MS). In 24 pairs, a firm clinical diagnosis was made on each twin. Among these 24 pairs, 6 of 12 monozygotic twins were concordant for clinical MS, compared with 2 of 12 dizygotic twins.Of those over the age of 50, two of three monozygotic pairs were concordant, but neither of the two dizygotic twin pairs were concordant. Because ascertainment was primarily through public announcement, this series may be biased in favor of twins concordant for MS. The individuals within monozygotic concordant twin pairs exhibited wide differences in severity and age at onset of disease; the more recently affected twin tended to have a lower cerebrospinal fluid (CSF) IgG and a higher IgM level. Although the frequency of HLA-B7 and Dw2 in this twin population was high, the HLA makeup did not differ appreciably between concordant and discordant MS twins. Furthermore, the two DZ-concordant twins were HLA-nonidentical. Unexplained neurologic signs were found in three asymptomatic twins, and a high proportion of clinically normal twins had abnormalities of CSF immunoglobulins. These latter findings suggest a high incidence of subclinical MS in this population.

Long-term treatment of chronic relapsing experimental allergic encephalomyelitis by transforming growth factor-β2

It had been demonstrated previously that the administration of transforming growth factor-beta 1 (TGF-beta 1) reduced the clinical severity of experimental allergic encephalomyelitis (EAE). Treatment with the related immunosuppressive molecule, TGF-beta 2, resulted in similar inhibition of T cell activation and proliferation in vitro. Long-term treatment was effective in reducing clinical severity of EAE and the number of relapses in mice receiving either myelin basic protein- or peptide-91-103-specific T cell lines. When examined histologically, mice that had received TGF-beta 2 demonstrated significantly less inflammation and demyelination in the central nervous system. Examination of other organs demonstrated no pathology or deleterious side effects from long-term TGF-beta 2 therapy. These findings have relevance for the use of TGF-beta 2 as a therapeutic agent for the human demyelinating disease, multiple sclerosis.

Nucleotide sequence analysis of a provirus derived from an individual with tropical spastic paraparesis

Human T-cell lymphotropic virus type 1 (HTLV-1), the cause of inapparent infections and T-cell leukemias and lymphomas, has also been implicated in two chronic neurological diseases, tropical spastic paraparesis (TSP) and HTLV-1 associated myelopathy (HAM). We initiated a search for a neurotropic variant of HTLV-1 that might be responsible for these chronic progressive myelopathies by cloning and sequencing a provirus from a T-cell line from an individual with TSP. The LTRs and genes of the TSP provirus differ from HTLV-1 by 20-30 nucleotides in each region, but none of the substitutions ostensibly affect functional sites with the exception of the env gene. We document one substitution in the region encoding gp46 common to TSP and HAM proviruses and a mutation that introduces two stop codons in the region encoding gp21. The latter should delete about 100 amino acids from the transmembrane anchor, and, for this reason, the progeny of the sequenced provirus are likely to be defective viruses, maintained in the culture through coinfection of cells with wild-type non-defective HTLV-1. While defective viruses could be responsible for persistent infection of the nervous system in TSP, this cannot be generally the case as we show that HTLV-1 DNA amplified from cell lines from two other individuals with TSP lacked the stop codons. Similarly, comparisons of DNA amplified from HTLV-1 DNA in cases of ATL, HAM, and TSP did not establish a correlation between the mutation in gp46 and neurological disease. The issue of neurotropic variants in HTLV-1 associated neurological disease thus remains an open one which may be resolved in the future by examining proviruses in cells in the lesions in the nervous system; or proviruses in ATL and HAM/TSP which differ in their ability to replicate in glial or neuronal cells.

EFFECT OF DIPHENYLHYDANTOIN ON NEUROMUSCULAR SYNAPSE.

THIS ARTICLE is about neuromuscular synaptic effects of diphenylhydantoin ( D P H ) . Its eflect on brainstem, spinal, and autonomic synapses has been reported by others.1-4 An effect of DPH on the neuromuscular junction would account for the beneficial effect of the drug i n Isaacs’ syndrome of “continuous muscle-fibre a ~ t i v i t y . ” ~ Our studies, however, stemmed from 2 clinical experiences with patients having disordered neuromuscular transmission associated with DPH administration for the treatment of epilepsy. These patients will be described first, although briefly, because there was inadequate evidence that DPH caused the neuromuscular disorder. Experiments with rat nerve-muscle preparations will then be described.