Aeropyrum pernix gen. nov., sp. nov., a novel aerobic hyperthermophilic archaeon growing at temperatures up to 100 degrees C

A novel aerobic hyperthermophilic archaeon was isolated from a coastal solfataric vent at Kodakara-Jima Island, Japan. The new isolate, strain K1, is the first strictly aerobic organism growing at temperatures up to 100 degrees C. It grows optimally at 90 to 95 degrees C, pH 7.0, and a salinity of 3.5%. The cells are spherical shaped and 0.8 to 1.2 microns in diameter. Various proteinaceous complex compounds served as substrates during aerobic growth. Thiosulfate stimulates growth without producing H2S. The core lipids consist solely of C25-isopranyl archaeol (glycerol diether). The G + C content of the genomic DNA is 67 mol%. Phylogenetic analysis based on 16S rRNA sequence indicates that strain K1 is a new member of Crenarchaeota. On the basis of our results, the name Aeropyrum pernix gen. nov., sp. nov. is proposed (type strain: K1; JCM 9820).

Molecular analysis of glucose phosphate isomerase deficiency associated with hereditary hemolytic anemia

We report here two new cases of glucose phosphate isomerase (GPI) deficiency associated with hemolytic anemia and present the results of molecular analysis of the five Japanese GPI variants. A Japanese girl (GPI Fukuoka) had an episode of prolonged neonatal jaundice and at 3 years of age was admitted due to acute hemolytic crisis occurring with upper respiratory tract infection. Red blood cell (RBC) GPI activity was decreased to 11.8% of normal and the reduced glutathione (GSH) level of RBCs was slightly decreased. A 54-year-old Japanese man (GPI Iwate) was hospitalized due to chronic active hepatitis, and compensated hemolysis was noted. RBC GPI activity of the proband was decreased to 18.8%, and the GSH content was about half of the normal mean value. Sequencing of the reticulocyte GPIcDNA showed homozygous missense mutations 1028CAG-->CGG (343Gln-->Arg), 14ACC-->A7C (5Thr-->lle), 671ACG-->A7G (224Thr-->Met), and 1615GAC-->AAC (539Asp-->Asn) in GPI Narita, GPI Matsumoto, GPI Iwate, and GPI Fukuoka, respectively. We also identified GPI Kinki as a compound heterozygote of 1124ACA-->AGA(375Thr-->Arg)/ 1615GAC-->AAC(539Asp-->Asn). Our findings, together with the previous results of other investigators, showed that the GPI gene mutations so far identified were heterogeneous, although most GPI variants had common biochemical characteristics such as heat instability and normal kinetics. Several amino acid substitutions were identified in the proximity of the catalytically important amino acid residues such as Ser/Asp 159/160, Asp341, and Lys518, which have been identified in the structural analysis of the pig GPI. The molecular characterization of human GPI variants, therefore, may provide new insights into the genotype-phenotype correlation of GPI deficiency as well as the structure-function relationship of this enzyme.

Transcript map of the human chromosome 4p16.3 consisting of 627 cDNA clones derived from 1 Mb of the Huntington's disease locus

Six hundred and twenty-seven cDNA clones from human brain cDNA libraries were characterized and integrated into a transcript map of the 1-Mb region on human chromosome 4p16.3 containing the Huntington's disease (HD) gene. Six hundred and seventy-two cDNA clones were obtained by a direct screening of the cDNA libraries, probing with pools of single copy microclones generated from the HD region specific yeast artificial chromosome (YAC)-DNA. So far, 93% of the obtained clones (627 cDNA clones) have been mapped onto the 1-Mb HD gene region by hybridization with HD region-specific cosmid, P1 and YAC clones. DNA sequence and expression analyses revealed that several cDNA clones might encode novel genes, some of which are situated within or close to the IT15, IT11, and alpha-adducin (ADD1) gene region, suggesting the presence of the overlapping genes in this region. This collection of cDNA clones will greatly facilitate the construction of the complete map of the transcripts in the HD region.

Purification and characterization of phosphoenolpyruvate carboxylase from the hyperthermophilic archaeon Methanothermus sociabilis

Phosphoenolpyruvate carboxylase (PEPC) was purified for the first time from hyperthermophilic archaeon Methanothermus sociabilis, growing autotrophically with an optimum at 88 degrees C. The optimum temperature for enzyme activity was similar to that for growth and was 85 degrees C. The native enzyme was a homotetramer of 240 kDa molecular mass and the subunit displayed an apparent molecular mass of 60 kDa. The archaeal PEPC was insensitive to various metabolites which are known as allosteric effectors for most bacterial and eucaryal counterparts. The enzyme showed extreme thermostability such that there remained 80% of the enzyme activity after incubation for 2 h at 80 degrees C. These results implied that archaeal PEPC was significantly different from bacterial and eucaryal entities.

Epstein-Barr virus-associated undifferentiated carcinoma with lymphoid stroma of the salivary gland in Japanese patients. Comparison with benign lymphoepithelial lesion

BACKGROUND

Undifferentiated carcinoma with lymphoid stroma (UCLS) arising in the salivary gland is a rare tumor, except for its geographic concentration among Eskimo and southern Chinese populations. Five cases of salivary gland UCLS in Japanese patients are presented here and compared with benign lymphoepithelial lesions (BLELs) with regard to their association with Epstein-Barr virus (EBV), p53 expression, and cell proliferative activity.

METHODS

Formalin fixed, paraffin embedded sections of 5 cases of UCLS selected from 1676 patients with primary tumors of the major salivary gland and 7 cases of BLEL were examined using in situ hybridization for EBV-encoded RNAs (EBERs), along with immunostaining for p53 and Ki-67 (MIB-1).

RESULTS

The incidence of UCLS was 0.3% among patients with major salivary gland tumors. EBER hybridization signals were strongly expressed in most of the neoplastic cells in all five cases of UCLS, whereas there was no signal in BLEL and surrounding nontumorous salivary gland tissues. All cases of UCLS showed strongly positive immunostaining for p53 in the tumor cell nuclei. By contrast, only one case of BLEL was positively stained for p53 in dysplastic epimyoepithelial cells, which showed focal immunostaining. Cell proliferative activity assessed using the Ki-67 labeling index was significantly higher in tumor cells of UCLS than in epimyoepithelial cells of BLEL.

CONCLUSIONS

UCLS of the salivary gland is an extremely rare tumor in Japanese patients characterized by consistent association with EBV. Distinction between BLEL and UCLS is possible by examining for evidence of EBV infection, expression of p53, and cell proliferative activity.

A combination chemotherapy with low doses of cytarabine and etoposide for high risk myelodysplastic syndromes and their leukemic stage. A pilot study

BACKGROUND

Even now, no definitely effective therapy is inducted to high risk myelodysplastic syndromes (MDS) and their leukemic stage (MDS-AML) except bone marrow transplantation.

METHODS

Ten patients with high risk MDS and 6 with MDS-AML were treated with daily low doses of cytarabine (10 mg/m2/12h, infused over 2h) etoposide (50 mg/m2/day, infused over 2h).

RESULTS

Fourteen of these patients were finally evaluated among whom 6 with high risk MDS and 3 with MDS-AML (64.3%) had complete remission, and 2 with high risk MDS (14.3%) achieved partial remission after this chemotherapy for 9 to 21 days. Three of 11 responders were resistant to the prior chemotherapies with single and low dose cytotoxic agents including cytarabine, etoposide, or aclarubicin. Although all of the patients who could be assessed developed severe marrow hypoplasia after chemotherapy, the nonhematologic side effects were mild enough to be tolerated.

CONCLUSIONS

This combination chemotherapy must be effective and useful in high risk MDS and MDS-AML not only without prior chemotherapy but in cases which have been resistant to single and low dose oncostatic agent.

Electrophysiological responses of three chemosensory systems in the carp to pesticides

Responses of three chemical senses, olfaction, taste, and pit organ sense, to three pesticides were studied electrophysiologically in carp, Cyprinus carpio. Only olfaction was responsive to the three pesticides at behavioral avoidance levels, which were determined in a previous study. The olfactory thresholds for benthiocarb, isoprothiolane, and fenitrothion were 1.7 x 10(-1) micrograms/l (4 log units lower concentration than 48-h LC50), 6.7 x 10(-3) micrograms/l (6 log units lower than 48-h LC50), and 4.9 x 10(2) micrograms/l (1 log unit lower than 48-h LC50), respectively. There were two distinctive features in the olfactory response to pesticides. One is that these pesticides barely indicated the concentration dependency that is usually recognized in the olfactory response to a typical stimulant such as L-alanine or NaCl. Another is that these pesticides indicated a power spectrum with an overall increase in frequency ranges of less than 10.0 Hz, unlike L-alanine or NaCl, which show a marked peak ranging from 8.0 to 12.0 Hz. These findings suggest that there is a specific mechanism in the chemoreception for these pesticides.

Recombinant human c-Mpl ligand is not a direct stimulator of proplatelet formation in mature human megakaryocytes

To evaluate the effect of the c-Mpl ligand on platelet production by megakaryocytes, we investigated proplatelet formation in isolated human megakaryocytes cultured in serum-free medium, with or without the c-Mpl ligand, interleukin-6 and erythropoietin. When interleukin-6 was added to the culture medium, the percentage of megakaryocytes displaying proplatelets was approximately 1.5-fold the control value; whereas, in the presence of the c-Mpl ligand, the percentage of megakaryocytes displaying proplatelets decreased in a dose-dependent manner and did not increase compared to control values at any dose tested. However, the viability of megakaryocytes after a 4 d culture in the presence of the c-Mpl ligand was significantly higher than that of the cells cultured without it. The c-Mpl ligand did not stimulate the proplatelet formation in megakaryocytes in vitro.

Reduction of 123I-iomazenil uptake in haemodynamically and metabolically impaired brain areas in patients with cerebrovascular disease

Iomazenil is a specific ligand for central-type benzodiazepine receptors (BZR). In order to determine the clinical significance of the findings of 123I-iomazenil single photon emission tomography (SPET) in cerebrovascular disease (CVD), we compared the cerebral uptake of 123I-iomazenil with oxygen metabolism measured by positron emission tomography (PET). Depending on the severity of the haemodynamic and/or metabolic impairment based on our institutional criteria [a reduction of < 30.6 ml 100g-1 min-1 in cerebral blood flow (CBF) and an increase of > 0.52 in the oxygen extraction fraction (OEF)], the cortical areas were classified into four groups as follows: Group I, normal CBF and OEF; Group II, normal CBF and increased OEF; Group III, reduced CBF and normal OEF; Group IV, reduced CBF and increased OEF. Seven patients (mean age 65 +/- 7 years) with CVD underwent both PET and 123I-iomazenil SPET within 8 days. The ratios of the mean counts in 14 regions of interest in the cerebral cortices to those in the cerebellar cortices (R/C ratios) were compared with the cerebral metabolic rate of oxygen (CMRO2). The R/C ratios of Group IV were lower than those of Group I (P < 0.005). The R/C ratios correlated with CMRO2 in Group III (r = 0.577, P < 0.01) and in Group IV (r = 0.707, P < 0.005), but not in Groups I or II. These results suggests that reduced uptake in 123I-iomazenil SPET reflects oxidative hypometabolism causing neuronal damage in haemodynamically and metabolically impaired areas in patients with CVD. This information may be valuable when deciding therapeutic approaches.

Dopaminergic transplants suppress L-DOPA-induced Fos expression in the dopamine-depleted striatum in a rat model of Parkinson's disease

We examined the effects of MK-801, a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, and fetal ventral mesencephalic (VM) transplants on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced Fos protein expression in the dopamine (DA)-depleted striatum. Unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal pathway were produced in young adult female rats and grafting was performed 3 weeks later. Methamphetamine-induced rotational behavior recovered significantly on the 4th week after grafting. Immunohistochemical examinations of c-Fos and tyrosine hydroxylase (TH) were performed 3-4 months after grafting. L-DOPA (100 mg/kg, i.p.) markedly induced Fos-like immunoreactivity (FLI) in the DA-depleted striatum. Pretreatment with a large dose of MK-801 (3-4.5 mg/kg, i.p.) dose-dependently suppressed L-DOPA-induced FLI in the striatum. The stimulatory effect of L-DOPA on c-Fos expression observed within the lesioned striatum was suppressed by fetal VM transplants. It seemed that the graft-induced effect on FLI extended over a considerably larger area than that covered by the graft-derived TH-immunoreactive innervation. Taken together, these findings suggest that glutamatergic modulation is involved in the L-DOPA-induced c-Fos expression in the denervated striatum which is normalized by fetal VM transplants. It also seems likely that VM grafts suppress the L-DOPA-induced expression of transcriptional factors which might be involved in the mechanisms underlying various side effects of chronic L-DOPA therapy.

[The production of high sensitive anti-myeloperoxidase monoclonal antibodies and their sensitivity and specificity]

We produced anti-myeloperoxidase(MPO) monoclonal antibodies(moAb) to detect MPO sensitivity in leukemic cells by visual light microscopy. We got seven kinds of moAbs which showed different properties to MPO. These antibodies reacted to MPO in immature and mature neutrophils, monocytes and HL-60(human myeloid leukemic cell line) by immunochemical detection using the avidin-biotin complex(ABC) staining method, but the amounts of immune complex products were significantly different at each moAb. MPO2, MPO4, MPO9 and MPO13 moAbs blocked MPO activities but MPO5 showed no such inhibition. Most of the moAbs reacted to 59kD MPO moAb using the western blotting method, while MPO4 and MPO5 reacted to both 81kD and 89kD MPO precursors. This data suggests that these moAbs are useful to demonstrate a small amount of MPO in leukemic cells.

Diurnal heart rate variability in healthy subjects: effects of aging and sex difference

To study the effects of aging and gender, circadian profiles of heart rate variability were evaluated for 105 healthy volunteers by frequency domain analysis of a Holter electrocardiogram record. The low-frequency (LF) component representing cardiac beta-adrenergic function showed high values for the 0800-1200 period in male subjects and the 1200-2400 period in female subjects. The high-frequency (HF) component representing parasympathetic function showed a peak for the 0000-0600 period in both male and female subjects independent of age. Male subjects showed significantly higher %LF [LF/(LF + HF) x 100] than female subjects. LF showed consistently highly significant correlation with age. These basic findings can help elucidate the diurnal profile of cardiac nerve function and how it is affected by aging and sex difference.

[Evaluation of remote effect to supratentorial areas in cerebellar infarction: a semiquantitative analysis using 99mTc-HM-PAO SPECT]

We studied 18 patients with unilateral cerebellar infarction to investigate its remote effect to the supratentorial areas with 99mTc-HM-PAO SPECT. Asymmetry indexes (AI) were calculated in the cerebellum and in seven supratentorial areas (thalamus, basal ganglia, superior and inferior frontal areas, temporal area, parietal area and occipital area). Mean AIs of supratentorial areas ranged from -0.64 +/- 2.74% to +1.04 +/- 2.03%. In cerebellar infarction of acute or subacute phase, the mean AI showed larger values (+1.13%) than that of chronic phase (+0.21%), but this difference did not reach statistical significance. There was no significant difference among supratentorial AIs grouped according to cerebellar infarction size. There was also no significant correlation among AIs of cerebellar and the supratentorial areas (r = -0.32 to +0.38). Crossed hemispheric hypoperfusion is thought to be related to the interruption of cerebellocortical tracts. We concluded that the detection of the remote effect to supratentorial areas in cerebellar infarction was difficult with 99mTc-HM-PAO SPECT.

Progesterone and dexamethasone stimulate proliferation and differentiation of osteoprogenitors and progenitors for adipocytes and macrophages in cell populations derived from adult rat vertebrae

We investigated the effects of the sex hormone progesterone (Prog) and the synthetic glucocorticoid dexamethasone (Dex) on proliferation and differentiation of progenitor cells of osteogenic, adipocytic, and hemopoietic lineages in cell populations derived from explants of adult female rat lumbar vertebrae. The cell populations were obtained by culturing bone explants in plasma clots immersed in alpha-minimum essential medium plus 10% fetal calf serum (standard medium) and then subculturing the outgrowth cells in standard medium plus 50 micrograms/ml of ascorbic acid, 5 mM beta-glycerophosphate, and with or without Prog or Dex. On day 6 of culture, these populations were analyzed for cAMP responses to parathyroid hormone (PTH), prostaglandin E2 (PGE2), and isoproterenol (IPT). Increases in intracellular cAMP were seen in response to PTH, PGE2, and IPT, and culturing in medium containing Prog increased these responses. At various time periods between days 4-27 of culture, the cultures were evaluated for the presence of bone nodules, alkaline phosphatase (AP)-positive colonies, adipocytes, monocytes, and macrophages. Prog and Dex increased the number of bone nodules and AP-positive colonies. The effect of Prog on bone nodule formation was smaller than that of Dex. In addition, the effect of Dex on bone nodule formation was evident after 10 days of culture, while the Prog-induced effects became significant at days 16-20 of culture. Both hormones also increased the number of Sudan IV-positive colonies (adipocytes), certain types of alpha-naphthyl butyrate esterase (alpha-NBE)-positive colonies (monocytes, macrophages, and T-lymphocytes), and ED2-positive colonies (macrophages). Prog-treated cultures contained more colonies of small spindle-shaped alpha-NBE-positive cells and fewer colonies of small round alpha-NBE-positive cells when compared with Dex-treated cultures. These data indicate that cell populations derived from adult rat lumbar vertebrae contain, among others, osteoprogenitors and progenitors for adipocytes and macrophages that are stimulated to proliferate and differentiate by Prog and Dex. The data also suggest that the effects of Prog and Dex differ qualitatively and quantitatively.

VLDL triglyceride kinetics in Wistar fatty rats, an animal model of NIDDM: effects of dietary fructose alone or in combination with pioglitazone

The effects of dietary fructose alone or in combination with a new oral agent, pioglitazone, on VLDL-triglyceride (TG) turnover were studied in genetically obese Wistar fatty rats characterized by hyperinsulinemia (7,488 +/- 954 pmol/l), hyperglycemia, (22.5 +/- 1.4 mmol/l), and hypertriglyceridemia (4.39 +/- 0.54 mmol/l). They had an increased hepatic TG production (16.2 +/- 0.1 micromol/min; lean rats, 5.4 +/- 0.3 micromol/min) as well as a longer half-life of VLDL-TG from lean donors (8.8 +/- 1.4 min, lean recipients; 2.3 +/- 0.9 min). In addition, in lean recipients, the half-life of VLDL-TG from fatty donors was longer than that from lean donors (4.80 +/- 0.56 vs. 3.14 +/- 0.23 min). Although feeding fructose into fatty rats did not change plasma glucose and insulin levels, it produced a twofold increase in TG levels (8.74 +/- 1.15 mmol/l). This was associated with a 1.7-fold increase in TG production to 27.5 +/- 1.2 micromol/min, while no significant change was found in the half-life of lean VLDL-TG in fructose-fed fatty recipients (10.9 +/- 2.4 min) or in that of VLDL-TG from fructose-fed fatty donors in lean recipients (4.46 +/- 0.76 min). Daily administration of pioglitazone (3 mg/kg body weight) in fructose-fed fatty rats ameliorated glycemia and triglyceridemia to the level of lean rats (8.1 +/- 0.7 and 1.18 +/- 0.05 mmol/l, respectively) and insulinemia to a lesser extent (2,712 +/- 78 pmol/l). A fall in TG levels was associated with improvement of an impairment in the ability of fructose-fed fatty rats to remove lean VLDL-TG (half-fife: 2.6 +/- 0.6 min). Pioglitazone, however, produced no change in TG production (25.9 +/- 2.7 micromol/min), the half-life of VLDL-TG from fructose-fed fatty donors in lean recipients (4.17 +/- 0.38 min), or the activity of lipoprotein lipase and hepatic lipase in postheparin plasma. We conclude that in Wistar fatty rats 1) hypertriglyceridemia is attributed to TG overproduction and impaired TG catabolism, and the latter is due to changes in both VLDL, such that they are less able to be removed, and changes in the nature of Wistar fatty rats, such that they are less able to remove VLDL-TG; 2) fructose further increases hepatic TG production with a resultant deterioration in hypertriglyceridemia; 3) pioglitazone normalizes TG levels by altering the physiology of the Wistar fatty rats in a manner that increases their ability to remove VLDL-TG from the circulation.

High efficiency transformation of maize (Zea mays L.) mediated by Agrobacterium tumefaciens

Transformants of maize inbred A188 were efficiently produced from immature embryos cocultivated with Agrobacterium tumefaciens that carried "super-binary" vectors. Frequencies of transformation (independent transgenic plants/embryos) were between 5% and 30%. Almost all transformants were normal in morphology, and more than 70% were fertile. Stable integration, expression, and inheritance of the transgenes were confirmed by molecular and genetic analysis. Between one and three copies of the transgenes were integrated with little rearrangement, and the boundaries of T-DNA were similar to those in transgenic dicotyledons and rice. F1 hybrids between A188 and five other inbreds were transformed at low frequencies.

Dopaminergic transplants alter in vivo activity of tryptophan hydroxylase in the striatum in a rat model of Parkinson's disease

L-3,4-Dihydroxyphenylalanine (L-DOPA) inhibits the activity of tryptophan hydroxylase (TRH) and thus serotonin synthesis. This inhibitory effect of L-DOPA may be related to some side effects in the patients under L-DOPA therapy. The effects of transplantation of fetal ventral mesencephalon (VM) on extracellular 5-hydroxytryptophan (5-HTP) accumulation was examined by microdialysis as an index of in vivo activity of TRH in the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rats. In the rat striatum perfused with m-hydroxybenzylhydrazine (NSD-1015; an inhibitor of aromatic L-amino acid decarboxylase), L-DOPA and 5-HTP in dialysate were measured simultaneously. In response to NSD-1015, 5-HTP levels were substantially elevated in the lesion plus VM-grafted striata as compared with those in the lesion plus sham-grafted striata. The results indicate that implantation of dopamine-rich VM grafts into the 6-OHDA-lesioned striatum of rats induces hyperactivity of TRH.

Expression of the PD-1 antigen on the surface of stimulated mouse T and B lymphocytes

A mAb J43 has been produced against the product of the mouse PD-1 gene, a member of the Ig gene superfamily, which was previously isolated from an apoptosis-induced T cell hybridoma (2B4.11) by using subtractive hybridization. Analyses by flow cytometry and immunoprecipitation using the J43 mAb revealed that the PD-1 gene product is a 50-55 kDa membrane protein expressed on the cell surface of several PD-1 cDNA transfectants and 2B4.11 cells. Since the molecular weight calculated from the amino acid sequence is 29, 310, the PD-1 protein appears to be heavily glycosylated. Normal murine lymphoid tissues such as thymus, spleen, lymph node and bone marrow contained very small numbers of PD-1(+) cells. However, a significant PD-1(+) population appeared in the thymocytes as well as T cells in spleen and lymph nodes by the in vivo anti-CD3 mAb treatment. Furthermore, the PD-1 antigen expression was strongly induced in distinct subsets of thymocytes and spleen T cells by in vitro stimulation with either anti-CD3 mAb or concanavalin A (Con A) which could lead T cells to both activation and cell death. Similarly, PD-1 expression was induced on spleen B cells by in vitro stimulation with anti-IgM antibody. By contrast, PD-1 was not significantly expressed on lymphocytes by treatment with growth factor deprivation, dexamethasone or lipopolysaccharide. These results suggest that the expression of the PD-1 antigen is tightly regulated and induced by signal transduction through the antigen receptor and do not exclude the possibility that the PD-1 antigen may play a role in clonal selection of lymphocytes although PD-1 expression is not required for the common pathway of apoptosis.

Lactate production of mammalian intestinal and vascular smooth muscles under aerobic and hypoxic conditions

Lactate liberation from thoracic aortas and intestinal smooth muscles of the guinea pig, rabbit and rat, as well as coronary arteries of the dog were determined'under aerobic and hypoxic conditions (95% N2 instead of O2). In all smooth muscles tested, the lactate liberation was inhibited in the presence of oxygen, being known as the Pasteur effect. The rates of lactate release from guinea pig aortas and taenia caeci under hypoxia were approximately 10 times greater than those under aerobic conditions. The rate of lactate release from other smooth muscles tested were 3-4 times greater under hypoxic than aerobic conditions. The extent of Pasteur effect was not affected by a removal of adventitial layer from the rabbit aorta nor by the different size of the dog coronary arteries. These results suggest that taenia caeci and aortas of the guinea pig intrinsically possess a strong regulatory system in the glycolytic activity, being highly sensitive to the presence of oxygen.

Change of immunological parameters in the clinical course of a myasthenia gravis patient with chronic graft-versus-host disease

The change in immunological parameters was studied during the clinical course of a myasthenia gravis (MG) patient with chronic graft-versus-host disease (GVHD), which developed after bone marrow transplantation from an HLA-identical donor. Anti-acetylcholine receptor antibody gradually decreased in the patient treated with immunosuppressive agents, but was not detected in the donor. Lymphocyte numbers were low just before the onset of MG, increased abruptly within several days and then gradually decreased with treatment. The percentage of CD3+ and CD19+ lymphocytes was higher at onset than before, the percentage of CD4+ cells was higher at onset and gradually decreased with treatment, while CD8+ cells showed the lowest level just before onset and gradually increased during the clinical course. CD4+/CD45RA- cells also showed the highest levels at onset and a gradual decrease with treatment. Cellular, as well as humoral immune responses, might be associated with the pathogenesis of MG with chronic GVHD.

Inactivation of human immunodeficiency virus (HIV)-1 envelope-specific CD8+ cytotoxic T lymphocytes by free antigenic peptide: a self-veto mechanism?

Free peptide has been found to inhibit cytotoxic T lymphocyte (CTL) activity, and veto cells bearing peptide-major histocompatibility complex (MHC) complexes have been found to inactivate CTL, but the two phenomena have not been connected. Here we show that a common mechanism may apply to both. CD8+ CTL lines or clones specific for a determinant of the human immunodeficiency virus (HIV) 1 IIIB envelope protein gp160, P18IIIB, are inhibited by as little as 10 min exposure to the minimal 10-mer peptide, I-10, within P18IIIB, free in solution, in contrast to peptide already bound to antigen-presenting cells (APC), which does not inhibit. Several lines of evidence suggest that the peptide must be processed and presented by H-2Dd on the CTL itself to the specific T cell receptor (TCR) to be inhibitory. The inhibition was not killing, in that CTL did not kill 51Cr-labeled sister CTL in the presence of free peptide, and in mixing experiments with CTL lines of different specificities restricted by the same MHC molecule, Dd, the presence of free peptide recognized by one CTL line did not inhibit the activity of the other CTL line that could present the peptide. Also, partial recovery of activity could be elicited by restimulation with cell-bound peptide, supporting the conclusion that neither fratricide nor suicide (apoptosis) was involved. The classic veto phenomenon was ruled out by failure of peptide-bearing CTL to inactivate others. Using pairs of CTL lines of differing specificity but similar MHC restriction, each pulsed with the peptide for which the other is specific, we showed that the minimal requirement is simultaneous engagement of the TCR and class I MHC molecules of the same cell. This could occur in single cells or pairs of cells presenting peptide to each other. Thus, mechanistically, the inhibition is analogous to veto, and might be called self-veto. As a clue to a possible mechanism, we found that free I-10 peptide induced apparent downregulation of expression of specific TCR as well as interleukin 2 receptor, CD69, lymphocyte function-associated antigen 1, and CD8. This self-veto effect also has implications for in vivo immunization and mechanisms of viral escape from CTL immunity.

Hypereosinophilic syndrome with generalized myasthenia gravis

A patient with hypereosinophilic syndrome simultaneously had generalized myasthenia gravis. Ultrastructural and functional studies demonstrated an increase of the activated hypodense eosinophils. The eosinophilic cationic protein level in plasma and whole blood paralleled the severity of congestive heart failure. A high level of interleukin-5 was detected in both serum and in conditioned medium of T cells by interleukin-2 stimulation before therapy. The findings indicate that both diseases may be associated with a common T-cell abnormality.