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K B Reid

Publications and source records attributed to K B Reid.

At least 91 records · Page 5Linked to original sources
PubMed1994

Primary structure of bovine collectin-43 (CL-43). Comparison with conglutinin and lung surfactant protein-D.

Collectin-43 (CL-43) is a bovine serum protein that is composed of subunits of three identical chains, each of which contains a collagen region and a C-type carbohydrate recognition domain; thus, CL-43 belongs to the collectins (group III of the C-type lectins). We have derived the complete primary sequence of CL-43 using partial protein sequencing, cDNA cloning, and reverse transcription-polymerase chain reaction techniques. The primary sequence of CL-43 shows that it contains an N-terminal region of 28 residues, followed by a collagenous domain of 38 repeats of Gly-Xaa-Yaa and then a C-terminal section of 159 residues, containing a short "neck" region and the carbohydrate recognition domain with the conserved residues found in all C-type lectins. The amino acid sequence of CL-43 showed 74% identity to bovine conglutinin and 70% identity to bovine lung surfactant protein D (SP-D), but the collagen region is considerably shorter than the 57 Gly-Xaa-Yaa triplets found in conglutinin and SP-D. Northern blot analysis showed that CL-43 was only synthesized in bovine liver, with no detectable signal in a variety of other bovine tissues, including lung. No cross-hybridizing signals were detected in mRNA from sheep, human, rat, or mouse liver. Since CL-43 and conglutinin have only been detected in members of bovidae, it is probable that an ancestral gene of these two proteins was first derived from a SP-D-like gene, and that this ancestral gene duplicated during evolution.

Amino Acid Sequence↗
PubMed1994

Expression of properdin in human monocytes.

Properdin is the only known positive regulator of the alternative pathway of complement activation. Northern blot analysis of cell lines derived from fibroblasts, B-cells, hepatoma cells, and cells of the monocyte-macrophage lineage revealed properdin expression only in the myelomonocytic cell line HL-60, in the monoblastic cell line U-937 and in the monocytic line Mono Mac 6. Culture of Mono Mac 6 cells for 24 h with phorbol 12-myristate 13-acetate, bacterial lipopolysaccharide and the cytokines interleukin-1 beta and tumour necrosis factor-alpha enhanced mRNA abundance, with the strongest effect (tenfold) being observed with the lipopolysaccharide. In contrast, recombinant interferon-gamma consistently halved properdin mRNA abundance. The same pattern was found for the secretion of properdin as detected by ELISA of Mono Mac 6 supernatants. The suppressive effect of interferon-gamma on properdin mRNA abundance was also demonstrated for primary blood monocytes. The data suggest that the expression and secretion of this complement regulatory protein by monocytes is differentially regulated by cytokines and link the immune response with alternative pathway activation.

Adult↗
PubMed1994

Surfactant proteins A (SP-A) and D (SP-D): levels in human amniotic fluid and localization in the fetal membranes.

Surfactant proteins A (SP-A) and D (SP-D) are major proteins, in the lung, which are composed of collagenous and globular domains. They show an overall similarity to the serum complement protein Clq, which is involved in the initiation of antibody-dependent defence mechanisms. Both SP-A and SP-D were detected, immunochemically, in amniotic fluid as early as 26 weeks gestation and, as expected, SP-A levels rose sharply from 32 weeks towards term. By contrast, SP-D levels in the same samples rose only moderately. Immunochemistry of paraffin sections of fetal membranes, revealed the presence of both SP-A and SP-D in the amniotic epithelium and chorio-decidual layers. SP-A and SP-D are both lectins and therefore they may play a role in the antibody-independent recognition and clearance of pathogens in the amniotic fluid.

Amniotic Fluid↗
PubMed1994

Collectins--soluble proteins containing collagenous regions and lectin domains--and their roles in innate immunity.

The collectins are a group of mammalian lectins containing collagen-like regions. They include mannan binding protein, bovine conglutinin, lung surfactant protein A, lung surfactant protein D, and a newly discovered bovine protein named collectin-43. These proteins share a very similar modular domain composition and overall 3-dimensional structure. They also appear to play similar biological roles in the preimmune defense against micro-organisms in both serum and lung surfactant. The close evolutionary relationship between the collectins is further emphasized by a common pattern of exons in their genomic structures and the presence of a gene cluster on chromosome 10 in humans that contains the genes known for the human collectins. Studies on the structure/function relationships within the collectins could provide insight into the properties of a growing number of proteins also containing collagenous regions such as C1q, the hibernation protein, the alpha- and beta-ficolins, as well as the membrane acetylcholinesterase and the macrophage scavenger receptor.

Amino Acid Sequence↗
PubMed1994

Mammalian lectins in activation and clearance mechanisms involving the complement system.

CRP and the mammalian lectins containing collagen-like structure (collectins) can clearly participate in a variety of antibody-independent recognition and clearance mechanisms which result in the neutralisation and elimination of pathogenic organisms (Fig. 2). Only CRP and MBP appear to have the capacity to activate complement, and while all the collectins (MBP, SP-A, SP-D and conglutinin) can utilise the C1q receptor, only conglutinin shows specificity for iC3b. The C-type lectin domains in the globular heads of the collectins have the capacity to recognise a range of specific carbohydrate structures which are found on the surfaces of pathogens commonly associated with infections in blood, lung and amniotic fluids. The proposed presentation of the carbohydrate-collectin complex to C1q receptors, via the collagen-like regions in the collectins is an attractive hypothesis for the triggering of protective mechanisms and there are already a number of publications which support this view. However, the precise manner by which these collagen 'stalks' interact with the C1q receptor and the complete characterisation of the receptor on a variety of different cell types remains to be elucidated. Similarly, whether or not there is a role for any of these lectins in autoimmunity/immunopathology has not, as yet, been addressed.

Animals↗
PubMed1993

Properdin, a positive regulator of complement activation, is expressed in human T cell lines and peripheral blood T cells.

Properdin plays an important regulatory role in the activation of the complement system. Here we report the biosynthesis of properdin in four different human T cell lines and in T cells purified from peripheral blood. Cell sorting experiments, in conjunction with Northern blotting, showed that both CD4- and CD8-bearing populations of T cells have the potential to synthesize properdin. The functional activity of properdin secreted from these T cell lines was determined in a hemolytic assay. In view of the numerous ways in which complement activation may influence cellular immune response, the present results indicate, for the first time, a possible interaction between the complement and the T cell system.

Adult↗
PubMed1993

Platelet activation by C1q results in the induction of alpha IIb/beta 3 integrins (GPIIb-IIIa) and the expression of P-selectin and procoagulant activity.

C1q receptors (C1qR) have been identified on a variety of somatic and cultured cells including peripheral blood platelets. Since platelets are likely to encounter both circulating C1q multimers and C1q associated with the extracellular matrix after complement activation by the classical pathway, the present study was designed to assess the effect of fluid phase and immobilized C1q on platelet function. Platelet adhesion to C1q-coated surfaces was accompanied by the induction of fibrinogen receptors. Scatchard analysis of fibrinogen binding to adherent platelets revealed the binding of approximately 10,000 molecules of fibrinogen per platelet with a Kd of 0.1 +/- 0.03 microM (mean +/- SD, n = 4). Furthermore, fluid phase C1q multimers were noted to aggregate platelets at doses > 5 micrograms/ml. This aggregation was preceded by a rise in inositol-1,4,5-trisphosphate (IP3) (6.9 +/- 2.4 pmoles/10(9) platelets at 15 s, n = 4), and activation of GPIIb-IIIa complexes supporting fibrinogen binding. Platelet aggregation in response to C1q multimers was accompanied by the aspirin-inhibitable release of granule contents and P-selectin (CD62) expression. Platelet aggregation was inhibited by the collagenous domain of C1q (c-Clq) and a monoclonal antibody directed against C1q receptors, suggesting the direct involvement of the 67-kD platelet C1qR. Antibodies against the very late antigen 2 or CD36 collagen receptors were without effect. Platelet exposure to C1q multimers was also accompanied by the expression of procoagulant activity, as demonstrated by the dose-dependent shortening of the kaolin recalcification time of normal plasma from 108 +/- 12 s in the presence of unstimulated platelets to 62 +/- 14 s in the presence of platelets that had been preincubated (5 min, 37 degrees C) with 100 micrograms/ml multimeric C1q (n = 3). These data suggest that platelet interactions with C1q multimers or immobilized C1q, resulting in the activation of GPIIb-IIIa fibrinogen binding sites and the expression of P-selectin as well as platelet procoagulant activity, are likely to contribute to thrombotic events associated with complement activation and inflammation.

Blood Coagulation↗
PubMed1993

Structural similarity between lung surfactant protein D and conglutinin. Two distinct, C-type lectins containing collagen-like sequences.

Preparations of bovine lung surfactant D (SP-D) and conglutinin were examined by electron microscopy, gel-filtration and SDS/PAGE. SP-D is composed of non-covalently linked subunits, of 160 kDa, which each contain three, disulphide-linked, 44-kDa polypeptide chains. In the electron microscope a single 160-kDa subunit of SP-D appears as a 45.8 +/- 3-nm-long rod connected to a small globular 'head'. Particles were also seen which correspond to non-covalently linked dimers, trimers and tetramers of the 160-kDa monomer subunit of SP-D. The tetramer structure contains 12 polypeptide chains and is very similar to the electron microscopy images and model reported by Strang et al. [Strang, C. J., Slayter, US., Lachmann, P. J. and Davis, A. E. (1986) Biochem. J. 236, 3811-389] for bovine conglutinin in which four 160-kDa subunits are disulphide-linked to give a molecule of expected molecular mass of 528 kDa. This study confirmed the findings by Strang et al. in the above paper for intact conglutinin and also emphasised that the rod-like structures, of length 37.6 +/- 3.7 nm, seen in the conglutinin subunits were significantly shorter than those in SP-D despite the close similarity in amino acid sequence (79% identify) and chain length between the two proteins. In addition, a truncated form of conglutinin was found in the conglutinin preparations, due to limited proteolysis of the Arg-Ala bond at position 54 in the 44-kDa chains. These truncated conglutinin chains yield a subunit composed of three shortened, non-disulphide-linked, chains and this subunit appears as a monomer with a rod length of 34.2 +/- 2.8 nm in the electron microscope. On gel-filtration, a proportion of the SP-D preparation behaved, as expected, as a molecule with an apparent molecular mass of 600 kDa. The remainder of the SP-D preparation behaved as aggregated material with a molecular mass greater than 900 kDa which yielded no distinct structures in the electron microscope. Intact conglutinin was eluted at a position greater than 900 kDa but yet provided clear electron microscopy images of the tetramer structure described above.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

The cDNA cloning of conglutinin and identification of liver as a primary site of synthesis of conglutinin in members of the Bovidae.

Bovine conglutinin is a collagen-like, C-type, plasma lectin which belongs to the group of proteins called 'collectins'. Two inosine-containing oligonucleotides were synthesized, based on the published protein sequence for bovine conglutinin [Lee, Leiby, Allar, Paris, Lerch and Okarma (1991) J. Biol. Chem. 266, 2715-2723], and PCR on target DNA from a bovine liver lambda gt 11 cDNA library yielded a product of the expected size of 210 bp. Screening of the library with this cDNA fragment identified a single positive clone, with an insert of 0.9 kb, coding for bovine conglutinin from residue 70 to the C-terminus. The 5' cDNA sequence, encompassing 150 bp of the 5' non-translated sequence plus the sequence encoding the leader peptide and the N-terminal residues 1-70, was completed by the use of PCR techniques. The cDNA sequence of bovine conglutinin showed 86% identity with that of bovine lung surfactant protein D (SP-D), and the derived amino acid sequence of bovine conglutinin showed 78% identity with that of bovine SP-D, which included complete identity of the leader-peptide sequences. The amino acid sequence derived from the cDNA sequence differs from the published protein sequence at four positions. Northern-blot analysis on total RNA, purified from various tissues from cattle, sheep, humans, rats and mice, showed that a strong signal of approx. 1.8 kb is present in bovine liver RNA. A weak signal of similar size was also observed in sheep liver, but not in human, rat and mouse livers. A weak signal, also of 1.8 kb, is present in the lung RNAs of all the species tested. The signals from the lung tissues are likely to be due to the cross-hybridization of the bovine conglutinin cDNA to the SP-D mRNAs of the respective species. The finding of significant signals in only the bovine and sheep liver RNA samples is indicative that serum conglutinin may be present in significant amounts only in members of the Bovidae (the family encompassing cattle, antelopes, sheep and goats) and closely related species.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of a bovine serum lectin (CL-43) with structural homology to conglutinin and SP-D and carbohydrate specificity similar to mannan-binding protein.

A previously undescribed bovine serum lectin (designated CL-43) was identified by its Ca(2+)-dependent binding to mannan and by its molecular mass of 43 kDa under reducing conditions on SDS-PAGE. The lectin was isolated by polyethylene glycol precipitation, affinity chromatography on mannan-Sepharose (followed by elution with EDTA), and absorption on Sepharose-4B-coupled rabbit anti-bovine Ig (to remove anti-mannan antibodies). Fractions containing the lectin were reapplied to mannan-Sepharose. Bound conglutinin was eluted with GlcNAc, and then the 43-kDa lectin, together with mannan-binding protein (MBP), was eluted with mannose. The 43-kDa lectin was separated from MBP by ion exchange chromatography on Mono-Q. On SDS-PAGE under nonreducing conditions the lectin showed a molecular mass of 120 kDa. On gel chromatography under nondissociating conditions the protein was eluted at a volume corresponding to a molecular mass of approximately 750 kDa. Amino acid analysis showed the presence of hydroxyproline and hydroxylysine and a high content of glycine (24.3%) indicating the presence of a collagen-like structure. This was supported by the susceptibility of the protein to collagenase digestion. The designation CL-43 was chosen since this molecule appears to belong to the collectins, i.e. proteins with collagen structure and lectin activity. The N-terminal sequence (27 amino acids) showed 56% identity with bovine SP-D and 44% identity to bovine conglutinin. An inhibition assay with biotinylated CL-43, using solid-phase mannan as ligand, revealed the following carbohydrate inhibition pattern: mannose and ManNAc > fucose > GlcNAc > glucose and maltose > galactose > lactose >> GalNAc. We conclude that CL-43 is a circulating lectin, with structural similarities to bovine conglutinin and SP-D, and a ligand binding profile resembling that of MBP.

Amino Acid Sequence↗
PubMed1993

Isolation of a human endothelial cell C1q receptor (C1qR).

C1q binding to endothelial cells has been described previously, but the putative cell surface receptor(s) has not been identified. In the present study, modifications of a reported purification of lymphocyte C1q receptor (C1qR) were used to isolate C1q binding sites from human umbilical vein endothelial cells. Cells were harvested, without protease treatment, at passage 10-17 and lysed with 1% Triton X-100. The lysate was fractionated on Fast-performance liquid chromatography (FPLC) Mono-Q using a linear NaCl gradient, followed by high-performance liquid chromatography (HPLC) ion exchange (TSKgel DEAE-NPR). A major protein was eluted that had the same mobility on sodium dodecyl sulfate-polyacrylamide gels and the same NH2-terminal sequence as lymphocyte C1qR. This protein was expressed on the surface, as judged by surface radioiodination, bound to C1q-coated surfaces, and was recognized by polyclonal antilymphocyte C1qR antibodies. Thus, endothelial cells express a C1q receptor that appears identical to lymphocyte C1qR. The data further support the hypothesis that cell surface C1qRs identified on a variety of somatic and cultured cells are either identical or constitute a family of closely related molecules.

Amino Acid Sequence↗
PubMed1993

Assignment of the human pulmonary surfactant protein D gene (SFTP4) to 10q22-q23 close to the surfactant protein A gene cluster.

Pulmonary surfactant consists of a complex mixture of phospholipids and several proteins essential to normal respiratory function. Two of the surfactant proteins, SP-A and SP-D, appear to have lectin-like activity relevant to the local phagocytic defense. Using polymerase chain reaction (PCR)-based somatic cell hybrid mapping, the human SP-D gene (SFTP4) was assigned to chromosome 10. A regional mapping panel was assembled and characterized using sequence tagged sites for five loci previously mapped to 10q. SFTP4, the SP-A gene (SFTP1), and the microsatellite D10S109 were placed in the interval 10q22-q23. Low-stringency PCR using the SFTP1 primer pair suggested the presence of at least two additional SP-A-related genes in the same region. With the locus for mannose-binding lectin (MBL) at 10q21, this may be indicative of this region's central role in the evolutionary history of carbohydrate-binding proteins containing collagen-like regions.

Animals↗
PubMed1993

Properdin.

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Chromatography, Affinity↗
PubMed1993

Purification and characterization of bovine mannan-binding protein.

Bovine mannan-binding protein (bMBP) was observed in serum by its Ca(2+)-dependent binding to mannan and by an M(r) of 28 kDa under reducing conditions on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The lectin was isolated by precipitation with polyethyleneglycol (PEG), affinity chromatography on mannan-Sepharose eluted with EDTA, and absorption on Sepharose 4B rabbit anti-bovine Ig to remove anti-mannan antibodies. Fractions containing the lectin were reapplied to mannan-Sepharose and eluted first with N-acetyl-D-glucosamine (GlcNAc) to remove conglutinin, and then with mannose to elute the 28 kDa lectin. Further purification was achieved by ion-exchange chromatography on Mono-Q and by mannose-gradient elution from a mannan-Sepharose column. SDS-PAGE of the purified lectin showed three high molecular weight bands under non-reducing conditions. The reduced protein gave a single band of 28 kDa. On gel permeation chromatography under non-dissociating conditions, the protein emerged at a volume corresponding to M(r) approximately 750 kDa. Amino acid analysis showed the presence of hydroxyproline and hydroxylysine, and a high glycine content (17.7%), suggesting the presence of a collagen-like structure. This was supported by the susceptibility of the protein to collagenase digestion. The N-terminal 26 amino acids showed 62% identity with human MBP, when three gaps were allowed in the alignment.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Comparison between liver and serum concentrations of mannan binding protein.

AIMS: To investigate staining patterns for mannan binding protein (MBP) by immunocytochemistry in liver biopsy specimens from patients with various hepatic disorders; to measure the serum MBP concentration in the patients at the time of biopsy; and to compare these to define further the role of MBP in disease. METHODS: Fifty seven consecutive patients with a variety of types of liver disease were studied. Fresh liver biopsy specimens were immunostained with anti-MBP and graded for intensity of staining. Serum MBP concentrations were measured on samples obtained on the day of biopsy, as were a full range of liver blood tests. RESULTS: MBP was only detectable in liver biopsy specimens from patients with morphological evidence of liver disease. MBP was most prominent in the livers of patients with severe alcoholic liver disease; livers harbouring metastases or showing biliary disease had moderate concentrations. Patients with liver disease were more likely to have raised serum MBP concentrations, but there was no correlation between these values and those found in the biopsy specimens. There was also no significant correlation between either of these concentrations and liver blood test abnormalities. CONCLUSIONS: Patients with liver disease tend to have raised MBP concentrations in both the liver and serum, but the exact relation between the two is as yet undefined.

Adolescent↗