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1.
Julien S. Fellah Fabienne Kerfourn Anne-Marie Dumay Geneviève Aubet Jacques Charlemagne 《Immunogenetics》1997,45(4):235-241
Polymerase chain reaction was used to isolate cDNA clones encoding putative T-cell receptor (TCR) α chains in an amphibian,
the Mexican axolotl (Ambystoma mexicanum). Five TCRα-V chain-encoding segments were identified, each belonging to a separate family. The best identity scores for
these axolotl TCRα-V segments were all provided by sequences belonging to the human TCRα-V1 family and the mouse TCRα-V3 and
TCRα-V8 families. A total of 14 different TCRA-J segments were identified from 44 TCRA-V/TCRA-J regions sequenced, suggesting that a large repertoire of TCRA-J segments is a characteristic of most vertebrates. The structure of the axolotl CDR3 α chain loop is in good agreement with
that of mammals, including a majority of small hydrophobic residues at position 92 and of charged, hydrophilic, or polar residues
at positions 93 and 94, which are highly variable and correspond to the TCRA-V/J junction. This suggests that some positions of the axolotl CDR3 α chain loop are positively selected during T-cell differentiation,
particularly around residue 93 that could be selected for its ability to makes contacts with major histocompatibility complex-associated
antigenic peptides, as in mammals. The axolotl Cα domain had the typical structure of mammalian and avian Cα domains, including
the charged residues in the TM segment that are thought to interact with other proteins in the membrane, as well as most of
the residues forming the conserved antigen receptor transmembrane motif.
Received: 12 June 1996 / Revised: 11 September 1996 相似文献
2.
Mutation in splicing consensus sequences causes lack of TCR membrane expression due to exon excision
T-cell antigen receptor (TCR) membrane-negative T-cell mutants can be divided into two groups: 1) those which lack one of
the six TCR polypeptides and 2) those which contain a mutated TCR chain. The present experiments reveal a new mechanism for
the development of TCR membrane-negative T-cell variants: mutations in splicing consensus motifs causing excision or misreading
of an entire exon (exon 3 of the TCRAC or TCRBC genes). C27.15 cells transcribe a TCR α chain consisting of TCRAVJCexon1Cexon2-encoded amino acids plus six new amino acids. The assembly defect seems to be that the truncated α chain does not interact
with CD3 δ molecules; consequently, no TCR αβ/CD3 δεγε complexes are formed. E6.E12 cells transcribe a TCR β chain composed
of TCRBVDJCexon1Cexon2-encoded amino acids plus twenty-seven new amino acids, which seem not to form a transmembrane region. The truncated β chain
does associate with CD3 γε heterodimers, yet no TCR αβ/CD3 δεγε complexes are made. This may be due either to low assembly
of TCR β/CD3 γε trimers or to lack of access of the mutated TCR β/CD3 γε trimers to the TCR α/CD3 δε compartment in the endoplasmic
reticulum.
Received: 25 September 1996 / Revised: 7 November 1996 相似文献
3.
J. M. Crous I. S. Pretorius W. H. van Zyl 《Applied microbiology and biotechnology》1996,46(3):256-260
First-strand cDNA was prepared from mRNA of Aspergillus niger MRC11624 induced on oat spelts xylan. Using the cDNA as a template, the α-L-arabinofuranosidase gene (abf B) was amplified with the polymerase chain reaction technique. The abf B DNA fragment was inserted between the yeast phosphoglycerate kinase I gene promoter (PGK1
P
) and terminator (PGK1
T
) sequences on a multicopy episomal plasmid. The resulting construct PGK1
P
-abf B-PGK1
T
was designated ABF2. The ABF2 gene was expressed successfully in Saccharomyces cerevisiae and functional α-L-arabinofuranosidase was secreted from the yeast cells. The ABF2 nucleotide sequence was determined and verified to encode a 449-amino-acid protein (Abf 2) that is 94% identical to the α-L-arabinofuranosidase B of A. niger N400. Maximum α-L-arabinofuranosidase activities of 0.020 U/ml and 1.40 U/ml were obtained with autoselective recombinant S. cerevisiae strains when grown for 48 h in synthetic and complex medium respectively.
Received: 29 January 1996/Received revision: 3 May 1996/Accepted: 9 May 1996 相似文献
4.
A new major histocompatibility complex class I b gene expressed in the mouse blastocyst and placenta
Susan L. Sipes Maxine V. Medaglia Deborah L. Stabley Craig S. DeBruyn Mark S. Alden Vicki Catenacci C. P. Landel 《Immunogenetics》1996,45(2):108-120
Because of the role major histocompatibility complex (MHC) class I b molecules may play during mouse embryonic development,
we thought it would be interesting to search for additional MHC class I b molecules that might be expressed in preimplantation
embryos, and in particular in the trophoblastic lineage. We therefore screened a mouse preimplantation blastocyst cDNA library
for MHC class I sequences. This search led to the identification and characterization of a new MHC class I b gene, blastocyst MHC. Sequences identical to the exons and 3′ untranslated region of this gene have been found in many laboratory mouse strains,
as well as in the related mouse species Mus spreciligus. The presence of this gene in mouse strains of different MHC class I haplotypes argues that blastocyst MHC is a unique, newly-described gene rather than a new allele of a previously described mouse MHC class I gene. Blastocyst MHC has the structure of an MHC class I b gene, with the six exons characteristic of T-region genes. It is linked to H2-D. The amino acid sequence encoded by this gene maintains all the features of a functional antigen-presentation domain. The
blastocyst MHC gene, like the human class I b gene HLA-G, is expressed at the blastocyst stage and in the placenta, and may be the mouse analog for HLA-G.
Received: 31 May 1996 / Revised: 19 August 1996 相似文献
5.
Total RNA was isolated from the diatom Cyclotella cryptica and separated into poly(A)+ and poly(A)− fractions. These fractions were subjected to in vitro translation/immunoprecipitation experiments using an antiserum directed
against the predominant light-harvesting complex of Cy. cryptica (ccry antiserum) and a heterologous antiserum raised against the light-harvesting complex of the cryptophyte Cryptomonas maculata (cmac antiserum). From translation reactions programmed with poly(A)+ RNA the ccry-antiserum immunoprecipitated polypeptides with relative molecular weights (Mr) of 27 000, 25 000, 23 000 and 21 000, while
the cmac-antiserum precipitated proteins with Mrs of 32 500 and 27 000, respectively. Subsequent cDNA synthesis and immunological
screening of the cDNA library with both antisera resulted in the isolation of six cDNA clones encoding light-harvesting subunits.
Full-length precursors were 199-210 amino acids in length and had Mrs of 20 000–23 000. The lengths of the putative signal peptides were 29 or 30 amino acids.
Pairwise comparison revealed that the similarity between the clones ranged from 54–99% on the nucleotide level and from 36–99%
at the amino acid level. In agreement with the data from the screens with the two antisera, the genes clustered into two groups.
The data provide evidence that the genes constitute a heterogeneous multigene family and that the light-harvesting system
of Cy. cryptica might be as complex as that of higher plants and green algae.
Received: 23 March 1998 / Accepted: 25 July 1998 相似文献
6.
C. A. McIntyre Robert C. Rees Kathryn E. Platts Catherine J. Cooke M. Olivia Smith Kevin A. Mulcahy Anna K. Murray 《Cancer immunology, immunotherapy : CII》1996,42(4):246-250
The MAGE gene family of tumour antigens are expressed in a wide variety of human cancers. We have identified 43 nonamer peptide sequences,
from MAGE-1, -2 and -3 proteins that contain binding motifs for HLA-A3 MHC class I molecules. The T2 cell line, transfected
with the cDNA for the HLA-A3 gene, was used in a MHC class I stabilisation assay performed at 37°C and 26°C. At 37°C, 2 peptides
were identified that stabilised HLA-A3 with high affinity (fluorescence ratio, FR >1.5), 4 peptides with low affinity (FR
1.11 – 1.49) and 31 peptides that did not stabilise this HLA haplotype (FR <1.1). At 26°C, 12 peptides were identified that
stabilised HLA-A3 with high affinity, 8 peptides with low affinity and 17 peptides that did not stabilise this HLA haplotype.
Two peptides stabilised HLA-A3 at both temperatures. Small changes in one to three amino acids at positions distinct from
the anchor residues altered peptide affinity. Data were compared to a similar study in which a peptide competition assay was
used to investigate MAGE-1 peptide binding to several HLA haplotypes. This study demonstrates that anchor residues do not
accurately predict peptide binding to specific HLA haplotypes, changes in one to three amino acids at positions distinct from
anchor residues influence peptide binding and alternative methods of determining peptide binding yield different results.
We are currently investigating the ability of these peptides to induce antitumour cytotoxic T lymphocyte activity as they
may be of potential therapeutic value.
Received: 4 January 1996 / Accepted: 20 March 1996 相似文献
7.
Amino acid and protein analyses have allowed the construction of a model for the C4-based Rodgers and Chido blood group antigens.
The single low-frequency allele (WH) in this blood group system, however, has not been characterized at the molecular level. Two WH+ donors were studied by C4 agarose gel electrophoreses, immunoblot studies using monoclonal anti-Rg: 1 or anti-Ch: 1, serological
phenotyping, polymerase chain reaction-restriction fragment length polymorphism of their C4 genes, and DNA sequencing of the WH allele. The first donor had the C4A1, A3 phenotype; the C4A1 carried Ch: 1, 3, 6 (thus exhibiting reversed antigenicity)
and the C4A3 carried the WH antigen. The amino acid sequence of the WH allele was PCPVLD at positions 1101 – 1106, S at position 1157, and VDLL at positions 1188 – 1191. A second donor typed as
C4A2, A4, B1 and was also WH+. Immunoblot analysis showed that a C4B1 protein expressed Rg: 1. Sequence analysis of the C4B genes showed the amino acids LSPVIH at positions 1101 – 1106, S at position 1157, and ADLR at positions 1188 – 1191. Thus,
the WH antigen is a conformational epitope that can arise through different mechanisms on either a C4A or C4B gene.
Received: 22 November 1995 / Revised: 19 February 1996 相似文献
8.
D. Vidović N. Boulanger Olabisi Kuye Joyce Toral Kouichi Ito Jeanmarie Guenot Horst Bluethmann Zoltan A. Nagy 《Immunogenetics》1997,45(5):325-335
Mutant mice generated by disrupting the H2-Aa
b
major histocompatibility complex (Mhc) gene are demonstrated here to express Aβb chains in the absence of α chains. These mice possess a CD4+ helper T cell (Th) repertoire that uses predominantly the Vβ7 T-cell antigen receptor (Tcr) segment for recognition of any
protein antigen presented by the α-free Aβ molecule. As an alloantigen, the Aα-free Aβ molecule is recognized very poorly
by T cells from a series of class II disparate mouse strains, indicating that it is grossly different from normal α/β heterodimers.
Indeed, molecular modeling suggests a β/β homodimer arrangement with an altered geometry of the Tcr contact area. Interestingly,
the mutant mice exhibit normal alloreactivity, without a restricted Vβ usage, toward a series of foreign α/β class II heterodimers,
although their T cells developed in the absence of such heterodimers. Thus, the complementarity of Tcr to normal α/β heterodimers,
and thereby also alloreactivity, appears to be an ontogeny independent (i. e., germline-encoded) feature.
Received: 30 September 1996 / Revised: 18 October 1996 相似文献
9.
Michelle Goldsworthy Anuradha Sampath J. M. Wilkinson S. H. Powis 《Immunogenetics》1997,46(3):206-212
Although many human major histocompatibility genes have been identified, relatively few have been localized to the class
I region. We searched for new class I region genes by sample sequencing, a process in which short stretches of random genomic
sequence are generated from cosmids and then compared with sequences deposited in nucleotide databases. Four class I region
cosmids were isolated for sample sequencing by screening a chromosome 6 specific cosmid library with probes derived from specific
class I region genes or with overlapping class I region yeast artificial chromosomes. Cosmids were sonnicated to produce fragments
of 0.5 – 1 kilobases, subcloned, and sequenced using an automated sequencer. Sequences were then compared with nucleotide
sequences deposited in the GenBank databases using the BLASTN algorithm. A number of potential new class I region genes were
identified, including a cDNA with similarity to the tre oncogene, the trans-activating factor SC1 (TCF19), and a member of the interferon inducible 1 – 8 gene family. These observations suggest that sample sequencing is an efficient method for identifying new class I region
genes, which can be applied to other regions of the genome and to other species, and support previous observations that the
class I region contains a variety of genes other than those encoding HLA antigens.
Received: 10 December 1996 / Revised: 7 January 1997 相似文献
10.
Saskia H. M. van Erp Brian Dixon Felipe Figueroa Egbert Egberts René J. M. Stet 《Immunogenetics》1996,44(1):49-61
In this study we report the finding of three representatives of a new group of major histocompatibility complex class I sequences
in carp: Cyca-12 (Cyca-UA1
*
01), a full-length cDNA; Cyca-SP1 (Cyca-UAW1), a polymerase chain reaction (PCR) fragment from cDNA; and Cyca-G11 (Cyca-UA1
*
02), a partial genomic clone. Comparison of the amino acid sequences of Cyca-12, Cyca-SP1, and Cyca-G11 with classical and non-classical class I sequences from other species shows considerable conservation in regions that
have been shown to be involved in maintaining the structure and function of class I molecules. The genomic organization of
Cyca-12 has been elucidated by analysis of a partial genomic clone Cyca-G11, in combination with PCR amplifications on genomic DNA of a homozygous individual. Although the genomic organization
is similar to that found in class I genes from other species, the 3′ untranslated region contains an intron which is unprecedented
in class I genes, and intron 2 is exceptionally large (±14 kilobases). Southern blot analysis indicates the presence of multiple
related sequences. In phylogenetic analyses, the Cyca-UA sequences cluster with class I genes from zebrafish and Atlantic salmon, indicating that the ancestral gene arose before
the salmonid/cyprinid split, approximately 120 – 150 million years ago. The previously reported class I Cyca-Z genes from carp and Caau-Z genes from goldfish cluster as a completely separate lineage. A polyclonal antiserum (anti-Cyca12) was raised against a recombinant fusion protein containing most of the extracellular domains of Cyca-12. The antibodies showed substantial reactivity to the recombinant protein and an M
r
45 000 protein in membrane lysates of spleen and muscle, as well as to determinants present on leucocytes in fluorescence-activated
cell sorter analyses. Erythrocytes and thrombocytes were found to be negative.
Received: 6 November 1995 / Revised: 16 January 1996 相似文献
11.
Trans-species polymorphism of class IIMhc loci in danio fishes 总被引:1,自引:1,他引:0
A characteristic feature of the major histocompatibility complex (Mhc) polymorphism in mammals is the existence of allelic lineages shared by related species. This trans-species polymorphism
has thus far been documented only in primates, rodents, and artiodactyls. In this communication we provide evidence that it
also exists in cyprinid (bony) fishes at the class II A and B loci coding for the α and β polypeptide chains of the class II α : β heterodimers. The study has focused on three species
of the family Cyprinidae, subfamily Rasborinae: the zebrafish (Danio rerio), the giant danio (D. malabaricus), and the pearl danio (D. albolineatus). The polymerase chain reaction was used to amplify and then sequence intron 1 and exon 2 of the class II B loci and exon 2 of the class II A loci in these species. Phylogenetic analysis of the sequences revealed the existence of allelic lineages whose divergence
predates the divergence of the three species at both the A and B loci. The lineages at the B locus in particular are separated by large genetic distances. The polymorphism is concentrated in the peptide-binding region
sites and is apparently maintained by balancing selection. Sharing of this unique Mhc feature by both bony fishes and mammals suggests that the main function of the Mhc (presentation of peptides to T lymphocytes) has not changed during the last 400 million years of its evolution.
Received: 6 December 1995 / Revised: 6 February 1996 相似文献
12.
Characterization of MHC class I and β2-microglobulin sequences in Atlantic cod reveals an unusually high number of expressed class I genes 总被引:1,自引:1,他引:0
Degenerate polymerase chain reaction (PCR) primers based on conserved residues from alignments of species with already characterized
major histocompatibility complex (MHC)-encoded sequences were used in the search for class I and β2-microglobulin (b
2
m) genes in Atlantic cod (Gadus morhua L.). After PCR amplification and subsequent sequencing a putative class I sequence was identified, from which a probe was
designed and used to screen a spleen cDNA library from one single individual. The full-length clone obtained was sequenced
and shown to be a classical Mhc class I-encoded sequence. It revealed the characteristic α1-, α2-, and α3-domains and transmembrane and cytoplasmic region,
with several conserved amino acids. A PCR amplification from the α2-domain to the CY-region was performed on the same library,
using a proof-reading enzyme. At least 11 unique additional sequences were isolated. Moreover, sequencing of the additional
cDNA clones resulted in a total of 17 different Mhc class I sequences in this individual. A Southern hybridization of DNA from four different individuals using an α3-specific
probe confirmed this large number of genes. Interestingly, based on differences mainly in their transmembrane region, the
sequences obtained could be divided into two distinct groups. Within the groups no support could be obtained for any further
subdivision. Southern experiments using an α1-specific probe gave almost the same restriction fragment length polymorphism
with a high number of hybridizing bands, suggesting a low divergence in this part of the gene. Sequencing of PCR clones obtained
with a proof-reading enzyme confirmed this at the nucleotide level. PCR amplification to isolate and characterize the b
2
m gene resulted in a sequence which was used to screen a thymus cDNA library. Two different alleles were obtained and these
showed the characteristic features of known teleostean β2m sequences. A Southern hybridization with genomic DNA from four different individuals suggested the presence of one b
2
m locus in Atlantic cod.
Received: 10 March 1999 / Revised: 1 June 1999 相似文献
13.
Horse (Equus caballus) immunoglobulin mu chain-encoding (IgM) variable, joining, and constant gene segments were cloned and characterized. Nucleotide sequence analyses of 15 cDNA clones
from a mesenteric lymph node library identified 7 unique variable gene segments, 5 separate joining segments, and a single
constant region. Based on comparison with human sequences, horse variable segments could be grouped into either family 1 of
immunoglobulin (Ig) clan I or family 4 of Ig clan II subclan IV. All horse sequences had a relatively conserved 16 base pair (bp) segment in framework 3 which was recognized
with high specificity in polymerase chain reaction by a degenerate oligonucleotide primer. Horse complementarity determining
regions (CDR) had considerable variability in predicted amino acid content and length but also included the presence of relatively
conserved residues and several canonical sequences that may be necessary in formation of the β chain main structure and conformation
of antigen-binding sites through interaction with light chain CDR. Sequence analysis of joining regions revealed the presence
of nearly invariant 3′ regions similar to those found in human and mouse genes. A single horse IgM constant region comprising 1472 bp and encoding 451 residues was also identified. Direct comparison of the horse constant
region predicted amino acid sequence with those from eleven other species revealed the presence of 53 invariant residues with
particularly conserved sequences within the third and fourth exons. Phylogenetic analysis using a neighbor-joining algorithm
showed closest similarity of the horse mu chain-encoding constant region gene to human and dog sequences. Together, these
findings provide insights into the comparative biology of IgM as well as data for additional detailed studies of the horse immune system and investigation of immune-related diseases.
Received: 14 October 1996 / Revised: 10 December 1996 相似文献
14.
Nassima Fodil Laurent Laloux Valérie Wanner Philippe Pellet Georges Hauptmann Nobuhisa Mizuki Hidetoshi Inoko Thomas Spies Ioannis Theodorou Seiamak Bahram 《Immunogenetics》1996,44(5):351-357
The hallmark of the classical major histocompatibility complex (MHC) class I molecules is their astonishing level of polymorphism,
a characteristic not shared by the nonclassical MHC class I genes. A distinct family of MHC class I genes has been recently identified within the human MHC class I region. The MICA (MHC class I chain-related A) gene in this family is a highly divergent member of the MHC class I family and has a unique pattern of tissue expression. We have sequenced exons encoding the extracellular α1, α2,
and α3 domains of the MICA gene from twenty HLA homozygous typing cell lines and four unrelated individuals. We report the identification of eleven new alleles defined by
a total of twenty-two amino acid substitutions. Thus, the total number of MICA alleles is sixteen. Interestingly, a tentative superimposition of MICA variable residues on the HLA-A2 structure reveals a unique pattern of distribution, concentrated primarily on the outer edge of the MICA putative antigen
binding cleft, apparently bordering an invariant ligand binding site.
Received: 13 May 1996 / Revised: 29 May 1996 相似文献
15.
The plant cytoskeleton has been implicated in a variety of morphogenetic events in higher plants. Most of this work, however,
has concentrated on epidermal cells or primary tissues. We have investigated the cortical microtubular (CMT) and microfilament
(MF) components of the cytoskeleton in a secondary tissue – active vascular cambium of Aesculus hippocastanum L. (horse-chestnut) – and followed the changes in these components during the early stages of differentiation of fusiform
cambial derivatives to axial elements of the secondary vascular system. A correlative approach was used employing indirect
immunofluorescence microscopy of α-tubulin on 6 μm sections, and transmission electron microscopy of 60 nm sections. The study
has demonstrated a rearrangement of the CMT cytoskeleton, from random to helical, as fusiform vascular cambial cells begin
to differentiate as secondary phloem vascular tissue. A similar CMT rearrangement is seen as fusiform cambial cells begin
to differentiate as secondary xylem fibres. This rearrangement is interpreted as evidence of determination of cambial derivatives
towards vascular development. Axially-oriented MF bundles are present in fusiform cambial cells and their axial orientation
is retained in the vascular derivatives at early stages of their development even though the CMTs have become rearranged.
Received: 5 August 1996 / Accepted: 23 September 1996 相似文献
16.
Philip O. Livingston Shengle Zhang Kenneth O. Lloyd 《Cancer immunology, immunotherapy : CII》1997,44(1):1-9
Resistance to chemotherapy is a major cause for failure in the treatment of lung cancer. Compared to conventional cytotoxic
drugs, immunotoxins act by different mechanisms and thus might be promising for the treatment of chemoresistant cancer. The
monoclonal antibody MOC31 recognises the epithelial glycoprotein-2 (EGP-2), a cell-surface antigen associated with small-cell
lung cancer (SCLC) and a major fraction of lung adenocarcinomas. An immunotoxin composed of MOC31 and a recombinant form of
Pseudomonas exotoxin A lacking the cell-binding domain (ETA252 – 613) was prepared, and its effect on lung cancer cell lines examined. MOC31-ETA252 – 613 was selectively cytotoxic to EGP-2-positive SCLC and adenocarcinoma cell lines inhibiting proliferation by 50% at concentrations
ranging from 0.01 nM to 0.3 nM. Moreover, the immunotoxin reduced the numberof clonogenic tumour cells from cultures by factors
of 104 and 105 during a 24-h and a 3-week exposure respectively. In athymic mice, the immunotoxin, which revealed a serum half-life of approximately
4 h, caused substantial regression of small (40 mm3) chemoresistant tumour xenografts and significantly delayed the growth of larger tumours (120 mm3). This finding indicates that MOC31-ETA252 – 613 may be useful for the treatment of lung cancer in the setting of chemoresistant minimal residual disease.
Received: 31 October 1996 / Accepted: 5 December 1996 相似文献
17.
Four cDNAs encoding the major histocompatibility complex (MHC) class I α chain were isolated from a channel catfish clonal
B-cell cDNA library. Sequence analysis suggests these cDNAs represent three different MHC class I loci. All cDNAs encoded
conserved residues characteristic of the MHC class I α chain: namely, those involved in peptide binding, salt bridges, disulfide
bond formation, and glycosylation. Southern blot analyses of individual outbred and second-generation gynogenetic fish indicated
the existence of both polygenic and polymorphic loci. Northern blot studies demonstrated that catfish B, T, and macrophage
cell lines transcribed markedly higher levels of class I α and β2-microglobulin (β2m) mRNA than fibroblast cell lines. In addition, immunoprecipitation data showed that a 41 000 M
r glycoprotein (presumably class I α) was associated with β2m on the surface of catfish B cells. This latter finding is the first direct evidence for the cell surface association of
β2m with the MHC class I α chain on teleost cells and supports the notion that functional MHC class I proteins exist in teleosts.
Received: 25 March 1998 / Revised: 28 July 1998 相似文献
18.
Induction of accessory cell function of human alveolar macrophages by inhalation of human natural interleukin-2 总被引:1,自引:0,他引:1
Gernot Zissel Walter E. Aulitzky J. Lorenz Christoph Huber J. Müller-Quernheim 《Cancer immunology, immunotherapy : CII》1996,42(2):122-126
Accessory function allows antigen-presenting cells to produce sufficient secondary signals for optimum T cell proliferation
and interleukin-2 (IL-2) production. Alveolar macrophages are inferior accessory cells compared to monocytes (PBM). We report
here that the accessory index (AI) of alveolar macrophages and PBM of patients with lung metastases of solid tumors treated
with inhalations of human natural IL-2 (hnIL-2) increased following its administration (P<0.005). The accessory index was significantly elevated from baseline values after 2 weeks of inhalation of 300 000 IU hnIL-2/day
(8.2±10.2 compared to 1.1±1; P<0.001). The inhalation of 150 000 IU also induced increases in the index (AI = 2.3±1.9), however, without reaching statistical
significance. In addition at 300 000 IU IL-2/day a significant increase in the accessory index was observed for PBM (4±2.5;
P<0.05). The indices of PBM and alveolar macrophages prior to inhalation showed a significant negative correlation with the
age of the patients (r
s = – 0.5; r
s = – 0.8, respectively; P<0.03 for all comparisons). Our data demonstrate that the inhalational application of hnIL-2 enhances the accessory function
of alveolar macrophages and, to lesser extent, the accessory index of PBM, indicating the occurrence of pharmacological immunostimulation.
Received: 16 August 1995 / Accepted: 4 January 1996 相似文献
19.
We have isolated an Arabidopsis BBM II isomerase cDNA from an Arabidopsis cDNA library, by means of functional complementation of the E. coli hisA mutant strain HfrG6. The isolated cDNA encodes a polypeptide of 304 amino acids with a calculated molecular weight of 33 363.
Sequence comparison with the HIS6 proteins of yeasts revealed that Arabidopsis BBM II isomerase contains an N-terminal extension of approximately 40 amino acids that shows the general properties of chloroplast
transit peptides. This finding is consistent with the localization of other histidine biosynthetic enzymes, such as imidazoleglycerolphosphate
dehydratase and histidinol dehydrogenase, in the chloroplasts in higher plants. The primary structure of the mature protein
was 50% and 42% identical, respectively, to the HIS6 proteins of Schizosaccharomyces pombe and Saccharomyces cerevisiae, respectively, while no prominent sequence similarity to the bacterial BBM II isomerase was found. That the isolated Arabidopsis cDNA actually encodes a functionally active BBM II isomerase activity was confirmed in an in vitro enzyme assay using a crude
extract prepared from strain HfrG6 transformed with the Arabidopsis BBM II isomerase cDNA.
Received: 2 February 1998 / Accepted: 21 April 1998 相似文献
20.
The immune capacity of young and adult axolotls (Ambystoma mexicanum) was evaluated by examining the combinatorial and junctional diversity of the VH chain. A large number of VDJ rearrangements isolated from 2.5-, 3.5-, 10-, and 24-month-old animals were sequenced. Six JH segments were identified with the canonical structure of all known vertebrate JHs, including the conserved Trp103-Gly104-X-Gly106 motif. Four core DH-like sequences were used by most (80%) of the VDJ junctions. These G-rich sequences had structures reminiscent of the TCRB DB sequences, and were equally used in their three reading frames. About 25% of the Igh, VDJ junctions from 3.5-month-old axolotls were out of frame, but most rearrangements were in frame at 10 and 24 months, suggesting
that there is active selection of the productively rearranged Igh chains in the developing animals. There was no significant
difference between the size of CDR3 in young (3.5 months) and subadult (10 months) axolotls (mean: 8.5 amino acids). However,
the CDR3 loop was 1 amino acid longer in 2-year-old adult animals (mean: 9.5 residues). Several pairs of identical VDJ/CDR3 sequences were shared between 3.5-month-old individually analyzed axolotls, or between groups of axolotl of different ages.
These identical rearrangements might be provided by the selection of some B-cell clones important for species survival, although
the probability that different 3.5-month-old axolotl larvae would produce identical junctions seems very low, considering
their limited number of B cells (less than 105). The high frequency of tyrosine residues and the paucity of charged residues in the axolotl CDR3 loops may explain the polyreactivity
of natural antibodies, and also clarify why it is so difficult to raise specific antibodies against soluble antigens.
Received: 11 March 1997 / Revised: 1 May 1997 相似文献