Search PubMed⌕ Search

Biomedical subjects

M A Kerr

Publications and source records attributed to M A Kerr.

At least 73 records · Page 4Linked to original sources
PubMed1990

The specificity of the IgA receptor purified from human neutrophils.

A receptor for IgA was purified from human polymorphonuclear neutrophils (PMN) by affinity chromatography on human serum IgA-Sepharose. The receptor appeared on SDS/polyacrylamide gels as a diffuse band with an apparent molecular mass of 50-70 kDa, whether reduced or non-reduced. During purification, the protein showed remarkable stability to proteolytic digestion by endogenous PMN proteinases. Purified radioiodinated receptor re-bound to IgA-Sepharose, but not to IgG-Sepharose or BSA-Sepharose. The binding of the receptor to IgA-Sepharose was inhibited in a dose-dependent manner by human serum IgA1 or IgA2 or secretory IgA1 or IgA2, but not by IgG or IgM. Binding of receptor to IgA-Sepharose was also inhibited by the Fc fragment of IgA, but not by the Fab fragment. An IgA fragment produced by digestion with pepsin which lacks the CH3 domain also inhibited binding, but to a more limited extent than did the whole IgA molecule.

Binding, Competitive↗
PubMed1990

Expression of the CD15 differentiation antigen (3-fucosyl-N-acetyl-lactosamine, LeX) on putative neutrophil adhesion molecules CR3 and NCA-160.

The expression of the carbohydrate antigen 3-fucosyl-N-acetyl-lactosamine (CD15, LeX) on human neutrophil glycoproteins has been studied by immunoprecipitation and immunoblotting by using monoclonal antibody MC2. The antigen is expressed on membrane glycoproteins of approximate molecular mass 165 and 105 kDa. These glycoproteins include the complement receptor and adhesion molecule, CR3, in which the beta-chain (CD18, 105 kDa) shows much greater expression than the alpha-chain (CD11b, 165 kDa). Most of the 165 kDa CD15 antigen is accounted for by expression on the carcinoembryonic antigen (CEA)-related molecule NCA160. Other members of this family, NCA95, NCA90 and NCA55, which are also found in neutrophils, do not express the CD15 antigen. There is a marked increase in the surface expression of CD15, CR3 and the antigen recognized by anti-CEA antibodies upon activation of neutrophils by the chemotactic peptide N-formylmethionyl-leucylphenylalanine.

Animals↗
PubMed1990

The expression of Lewis(a) and Lewis(b) antigens reflects changes in fucosylation between normal and neoplastic cervical squamous epithelium.

Antibodies against the carbohydrate antigens Lewisa (Lea) and Lewisb (Leb) allow further investigation into the changes in fucosylation of the glycocalyx occurring during the normal and neoplastic development of cervical squamous epithelium. Lea and Leb are expressed on a broad zone of suprabasal cells in normal cervical squamous mucosa often independent of individual Lewis gene and secretor status. A proportion of Lea is expressed in sialylated form. In cervical intraepithelial neoplasia, the progressive dedifferentiation of the squamous mucosa is mirrored by loss of both Lea and Leb expression. In invasive squamous carcinomas, Lea and Leb expression is seen only on cells in areas of differentiation. The expression of Lea and Leb in normal and neoplastic cervical squamous epithelium resembles that of the Lex antigen described by us previously. The structural similarity between these antigens is highlighted and evidence for a common functional role in maintaining the integrity of squamous mucosae is discussed.

Antibodies, Monoclonal↗
PubMed1990

A light and scanning electron microscope study of epithelial thickenings and rete ridges in the adult hamster cheek pouch.

Cheek pouches from 8 adult male BIO strain hamsters were removed; half of them were routinely processed for light microscopy. The epithelium and connective tissue of the remaining pouches were separated using EDTA. These tissues were routinely processed for scanning electron microscopy and their separated surfaces examined; after this, some were reprocessed for light microscopy. A total of 1200 sections were examined by light microscopy and of these, 414 had at least one area showing rete ridges. Scanning electron microscopy confirmed the presence of isolated areas of either single or multiple rete ridges on both the separated epithelial and connective tissue surfaces. The presence of isolated areas of rete ridge formation in normal adult hamster cheek pouch mucosa needs to be taken into account in studies on experimentally altered cheek pouches so that the ridges are not interpreted as being part of a pathological change.

Animals↗
PubMed1990

The effect of antibody isotype on the activation of C3 and C4 by immune complexes formed in the presence of serum: correlation with the prevention of immune precipitation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement during the formation of immune complexes in human serum by the interaction of DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. Those containing IgG2 or IgM were potent activators of C4, whilst IgG1 containing complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. All complexes except those containing IgA precipitated more slowly in serum than in buffer. IgG2 antibodies were potent activators despite being very slow to precipitate in buffer. In serum containing EGTA activation of C4 was abolished and precipitation of complexes occurred at the same rate as in buffer. Nevertheless, C3 activation still occurred by the alternative pathway for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. The ranking of the ability to activate complement was the same as that observed when performed complexes containing the same antibodies were added to serum. The levels of C4a generated were similar under both conditions but for most antibodies more C3a was generated by preformed complexes.

Antibodies, Monoclonal↗
PubMed1990

A proteolytic enzyme secreted by Proteus mirabilis degrades immunoglobulins of the immunoglobulin A1 (IgA1), IgA2, and IgG isotypes.

Proteus mirabilis strains associated with human urinary tract infections have previously been shown to secrete an extracellular metalloproteinase which cleaves serum immunoglobulin A (IgA). The enzyme has now been purified to apparent homogeneity from culture supernatants of P. mirabilis 64676. The protease activity is associated with a 50-kilodalton (kDa) protein. Unlike that of the classic IgA1 proteases, the substrate specificity of the P. mirabilis protease has been found to extend to both sublcasses of IgA, IgG, and the nonimmunoglobulin substrates, secretory component and casein. Cleavage of IgA1 and IgA2 by the P. mirabilis protease yielded fragments on sodium dodecyl sulfate-polyacrylamide gel electrophoresis whose sizes were consistent with a cleavage site outside the hinge region. Both secretory IgA1 and IgA2 were also cleaved by P. mirabilis protease, although the secretory IgA2 molecule was less readily cleaved than secretory IgA1. Free and IgA-bound secretory components were degraded to some extent by P. mirabilis protease. Cleavage of IgG, however, occurred at the hinge region as a two-stage process. The first stage was pepsinlike and generated an F(ab')2 fragment of 120 kDa and a small pFc fragment detected on nonreduced polyacrylamide gels. In the second stage, the F(ab')2 product was cleaved to yield papainlike Fab and Fc fragments, visualized as a diffuse band of 40 to 50 kDa.

Chromatography↗
PubMed1990

Expression of CD15 antigen in urinary bladder transitional cell carcinoma.

The biopsy specimens of 91 patients between the ages of 38 and 94 with transitional cell carcinoma of the bladder were retrospectively reviewed to determine if the expression of CD15 antigen detected by a monoclonal antibody MC2 was correlated with prognosis. Expression was variable, ranging from strong expression of the antigen by only the superficial cells in well differentiated papillary lesions to weak expression by most cells in solid or invasive tumours. In the invasive component there was a correlation between MC2 expression and tumour type, suggesting that the cell surface carbohydrate detected by MC2 may have a role in cell adhesion. There was no correlation between staining and survival. It is concluded that tumour type, grade, and stage remain the best prognostic indicators of urothelial tumours.

Adult↗
PubMed1990

The specificity of the human neutrophil IgA receptor (Fc alpha R) determined by measurement of chemiluminescence induced by serum or secretory IgA1 or IgA2.

Heat or chemically aggregated IgA or IgG stimulated degranulation of neutrophils with comparable efficiency. The same aggregates induced a neutrophil respiratory burst which could be measured by lucigenin-enhanced chemiluminescence. Serum IgA1 or IgA2 coated onto microtitre plates were both capable of inducing a respiratory burst in neutrophils, as was secretory IgA1 or secretory IgA2. All bursts were of similar size for a given concentration of IgA and were greater than the burst elicited by an equivalent concentration of IgG. For each subclass of IgA the respiratory bursts were dependent on their density on the opsonized surface. Since monomeric and dimeric forms present in secretory IgA preparations both elicit a respiratory burst in neutrophils, secretory component and J chain cannot block the receptor binding site on the Fc region. The potential of secretory IgA to act as an opsonin might have important consequences on mucosal surfaces where the availability of complement components is limited.

Antigens, CD↗
PubMed1989

Characterization of human neutrophil glycoproteins expressing the CD15 differentiation antigen (3-fucosyl-N-acetyllactosamine).

The expression of the CD15 antigen, 3-fucosyl N-acetyllactosamine, on neutrophil glycoproteins has been studied by SDS gel electrophoresis and immunoblotting. The antigen is expressed on several glycoproteins, both intracellularly and on the cell surface. Each subcellular compartment appears to contain a specific antigen. A soluble, granule glycoprotein (Mr 80-90K) probably accounts for most of the intracellular staining detected immunohistochemically. Membrane glycoproteins of Mr, 85-90K and 25K are associated with granule membranes, the latter being an integral membrane protein. The CD15 antigen is expressed on several cell surface glycoproteins with Mr in the range of 165K and 105K. These antigens are also contained in an intracellular pool which is brought to the surface on activation of the cells with chemotactic peptides. The 165K and 105K antigens show identical electrophoretic mobility to two of the major glycoproteins detectable by PAS or protein staining of gels of detergent extracts of cell membranes. These glycoproteins include the complement receptor, CR3. The beta chain of CR3 (105K) and to a lesser extent the alpha chain (165K) express CD15; however, most of the CD15 antigen is associated with other glycoproteins of these molecular masses.

Antibodies, Monoclonal↗
PubMed1988

Expression of the 3-fucosyl N-acetyllactosamine (CD 15) antigen in normal, metaplastic, dysplastic, and neoplastic squamous epithelia.

The 3-fucosyl N-acetyllactosamine residue is the antigen recognized by the monoclonal antibody MC2. Using MC2, we demonstrated the distribution of this antigen in a variety of squamous epithelia. The antigen is expressed to a variable degree on supra-basal cells in most normal non-keratinizing squamous mucosae, with a similar distribution in metaplastic squamous epithelia; antibody-labelled latex microspheres and immunogold electron microscopy show the antigen to form part of the glycocalyx. In dysplastic and neoplastic squamous lesions, expression is reduced or absent except in cells around areas of differentiation. Prior neuraminidase treatment of sections had little effect on the amount or distribution of demonstrable antigen. Expression of this antigen by cells in non-keratinizing squamous epithelia gives an indication of cell maturity and may provide a histological marker for the grading of dysplastic and malignant squamous mucosal lesions. A possible role for these carbohydrate residues in squamous mucosal defence is discussed.

Antigens, Neoplasm↗
PubMed1988

Expression of the CD 15 antigen is a marker of cellular differentiation in cervical intra-epithelial neoplasia (CIN).

The CD 15 antigen (3-fucosyl N-acetyllactosamine), present on the outer cell membrane of cervical squamous epithelial cells, is recognized by the monoclonal antibody MC2, which is similar to several commercially available antibodies. Staining sections of cervical biopsies with MC2 clearly demonstrates the zone of supra-basal differentiated cells in the normal squamous epithelium. Staining with MC2 also demonstrates the diminished proportion of this zone occurring with grades of CIN, reflecting progressive de-differentiation of the epithelium. In immature squamous metaplastic epithelium, absence of cytoplasmic differentiation is reflected by lack of staining. As expression of the CD 15 antigen by cervical squamous cells mirrors cytoplasmic maturity and is a marker of cellular differentiation, staining colposcopic biopsies with MC2 may aid the routine histopathological grading of CIN. A comparison is made between the staining pattern observed using MC2 with that of two commercially available antibodies (Leu M1 and Dako M1), and a possible role for the CD 15 antigen in cellular adhesion in squamous mucosae is discussed.

Antibodies, Monoclonal↗
PubMed1988

The activation of C3 and C4 in human serum by immune complexes containing mouse monoclonal antibodies of different isotype and affinity: effects on solubilisation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement in human serum by immune complexes containing DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. When preformed complexes were added to serum, those containing IgG2 or IgM were potent activators of C4, whilst IgG1 complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. Solubilisation of complexes was greatest for IgM and IgG2b and least for IgG2a and IgA. In serum containing Mg2+ EGTA C4 activation was abolished and the amount of C3 activation was lower for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. Unexpectedly, three of the four IgMs activated C3 in EGTA. For IgMs, neither complement activation nor solubilisation correlated with affinity. For IgG1 antibodies, solubilisation was inversely proportional to affinity. C3 or C4 activation did not correlate with affinity.

Animals↗
PubMed1988

A survey of IgA protease production among clinical isolates of Proteeae.

A collection of 100 strains of Proteeae, in which all species within the tribe were represented, was examined for IgA protease production. The strains were isolated from various clinical specimens from sick and healthy persons in several countries. IgA protease-producing strains were not found amongst species of Providencia and Morganella but were common in Proteus spp. All the strains of P. mirabilis and P. penneri and many of the strains of P. vulgaris examined produced an EDTA-sensitive protease that cleaved the IgA heavy chain outside the hinge region. The proteus enzyme was different in this respect from the EDTA-sensitive, hinge-cutting proteases of other bacteria. The ability to produce IgA protease was unrelated to the O antigenicity, biotype or bacteriocin type of the strain. IgA protease production may be an important virulence mechanism for Proteus strains.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Characterization of the IgA receptor from human polymorphonuclear leucocytes.

Human polymorphonuclear leucocytes (PMNs) will phagocytose yeasts opsonized with specific affinity-purified human serum IgA. PMNs also bind to Sepharose beads coated with IgA or IgG, but not to beads coated with bovine serum albumin (BSA) or horseradish peroxidase (HRP). Binding to IgA-Sepharose stimulates the cells to release lysozyme. Affinity chromatography of 125I-labelled PMN membrane proteins on IgA-Sepharose results in isolation of a polypeptide of apparent 60,000 MW. The protein, which is not bound to IgG-Sepharose under the same conditions, appears as a diffuse band on SDS-PAGE, suggesting it is heavily glycosylated.

Antigens, CD↗