Biomedical subjects
Publications and source records attributed to J Lowe.
A family is presented in which ano-rectal malformation and features common to Alport Syndrome appear to be present in three generations. The possibility of a new syndrome based on a single gene defect is discussed.
The properties of five monoclonal antibodies (McAbs) which react with free kappa chains but not with IgG kappa, IgM kappa or IgA kappa have been studied. IgG preparations stored for long periods sometimes contained low and high molecular weight material reacting as free kappa. This could be removed by passing the preparation through an affinity column to which two of the McAbs had been coupled, but reactive material reappeared when the purified IgG was heated at 65 degrees C. Two of the McAbs from one fusion reacted with F(ab')2 fragments of IgG whereas two from another fusion did not. Pairs of McAbs (one from each fusion) were much more sensitive in the detection of free kappa, particularly monomer, than a single McAb. This provided the basis for a very sensitive method of detection of free kappa chains in human body fluids and culture supernates.
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Electron micrographs of fracture callus obtained ten days after injury show typical primary matrix vesicle mineralization. In remodeling haversian canals distant from the fracture sites, matrix vesicles and calcifying nodules were observed. The occurrence of these elements was also found to control unfractured tibiae with intramedullary nails but not normal bone. These observations suggest that during haversian remodeling, mineralization after osseous or marrow tissue damage is associated with matrix vesicles.
A case is presented of local recurrence of tuberculosis after successful hip arthrodesis, in a patient subsequently found to have active asymptomatic renal tuberculosis. The possibility of hematogenous spread is raised, and the importance of thorough genitourinary evaluation in cases of reactivated skeletal tuberculosis is discussed.
Although non-toxic, 1,8-dinitropyrene (1,8-DNP) was mutagenic for mouse lymphoma L5178Y cell when assayed for induced resistance to 6-thioguanine, methotrexate, ouabain and 1-beta-D-arabinofuranosyl cytosine. In bacteria, nitropyrenes are potent inducers of frame-shift mutations, and the induction of ouabain-resistant mutants, believed to be due to base-pair substitutions, suggests that the mechanism of action may be different in mouse cells and bacteria. Long treatment time were required to detect 1.8-DNP-induced mutants in L5178Y cells, suggesting the possibility of an inducible activation system. 4-Nitroquinoline 1-oxide was both toxic and mutagenic to these same 4 mutation assays after short (2h) treatment times. The dilemma that exists when comparing the mutagenic potential of test chemicals when concentration of mutagen, treatment times and toxicity are markedly different, is discussed.
Twenty-three monoclonal antibodies with specificity for epitopes in the Fc fragment of IgG have been used to investigate antigenic differences between secreted and membrane forms of IgG produced by 2 human B lymphoblastoid cell lines (LCL). All of the monoclonals reacted with IgG secreted by the cell lines, as demonstrated by their ability to agglutinate SRBC coated with immunoglobulin isolated from culture supernatants. Membrane IgG expression was studied using direct and indirect rosette assays with antibody-coated ORBC. A surprisingly high number of antibodies, 13 on EB2 and 9 on EB4, did not bind to the cell surface immunoglobulin. These included antibodies with specificities for both C gamma 3 and C gamma 2 domain determinants. Similar results were obtained with an indirect radiobinding assay, indicating that negative results with the rosette test were not due to steric hindrance by the red cell carrier. Their performance in indirect hemagglutination indicated that most of the antibodies that did not bind to membrane IgG were of high avidity. It is concluded that the epitopes for which these antibodies are specific are not available on the cell surface. Possible explanations for the apparent antigenic differences between secreted and membrane forms of IgG are discussed against the background of previous work on the structure and mode of insertion of cell surface immunoglobulin.
Antibody-producing hybridoma clones have been isolated following immunization of mice with human IgG. Twenty-five monoclonal antibodies (nine anti-C gamma 3, fourteen anti-C gamma 2, one anit-kappa and one anti-lambda) were selected for study of their cross-reactivity with the IgG of fifteen mammalian species and chicken immunoglobulin. Each antibody exhibited a unique reaction profile suggesting that human IgG expresses a very large repertoire of immunogenic epitopes. Whilst some antibodies showed a very restricted cross-reactivity profile for others a very wide reactivity profile was observed-including two clones producing autoantibodies. Antibodies demonstrating cross-reactivity between human Fc gamma and 7S chicken immunoglobulin allow its definitive assignment as a homologue of human IgG. Four clones demonstrated specificity for bovine IgG subclass gamma 1 and gamma 2 and the degree of reactivity allows their application to qualitative and quantitative assay systems. These studies suggest new perspectives for the characterization of immunoglobulins and the standardization of anti-immunoglobulin reagents.
BALB/c mice were immunized with a human gamma 2k paraprotein and hybridomas prepared by the Kohler & Milstein technique. Ten hybridoma clones producing high levels of antibody competed reacting specificity with the immunogen were isolated. Six of the monoclonal antibodies competed strongly with each other for sites on the antigen. In reverse passive haemagglutination tests immunoglobulins reacting with the antibodies were not detectable in normal or pathological sera. Polyclonal antisera to two of the monoclonal antibodies were prepared in rabbits; they were rendered specific by adsorption with Sepharose-normal mouse IgG and tested against the other monoclonal antibodies. A weak cross-reaction of one of the mouse antibodies with the immunogen was observed with one antiserum but none with the other. Furthermore, no repetition of the idiotypes of the two immunogens was observed in polyclonal responses of BALB/c mice immunized with the same paraprotein antigen. These results with monoclonal antibodies confirm those obtained with polyclonal antisera in showing that the antibody response of one species to the private idiotype determinants of an immunoglobulin of another species is highly heterogeneous.
Immune complex formation of four different mouse monoclonal antibodies against human IgG has been studied using analytical zonal centrifugation. A theoretical model has been used to depict thermodynamic ideal immune complex formation of monoclonal antibodies. It was found that the four monoclonal antibodies differed very much with respect to immune complex formation with human IgG. One of the monoclonal antibodies formed immune complexes in agreement with the theoretical model. Another was strongly related thereto. A third monoclonal antibody formed only a single complex and might exhibit a positive co-operativity between its two sites. A fourth formed as excess of a possibly cyclic complex. Thus monoclonal antibodies differ substantially with respect to physical properties adding a new aspect to the problems of antibody heterogeneity. It is moreover found that analytical zonal centrifugation can be used to estimate the number of antigenic determinants and antibody-binding sites thereby assuring whether or not a particular IgG monoclonal antibody has two binding sites.
Thirteen monoclonal antibodies (McAbs) showing subclass-specific and subclass-restricted reactivity to human IgG have been produced by the hybridoma technique. Their specificity has been defined by passive haemagglutination (HA) and haemagglutination-inhibition (HAI) assays using a large panel pf purified IgG paraproteins of known subclass. Their use in assaying human IgG subclasses in radial immunodiffusion (RID) and in purifying human subclasses by both positive and negative immunoabsorption chromatography is illustrated.
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We have compared free serum histidine in patients with rheumatoid arthritis, their blood relatives, and their non-blood relatives. The hypohistidinaemia of rheumatoid arthritis is acquired with the disease and does not provide a biochemical marker of those at risk.
Sera from 41 patients with lung cancer and 41 age and sex-matched hospital inpatients with non-malignant disease were tested for the presence of immune complexes using the 125Iodine Clq binding test. All patients were untreated or had recurrences after surgery. An increased Clq binding activity was found in 34% of patients with lung cancer and 24% of patients with non-malignant disease. There was no significant association between increased serum Clq binding activity and histological tumour type or survival but there was an association with the extent of malignant disease. No patient with limited (state 1) disease had raised Clq binding activity but in 42% of patients with extensive disease it was increased. Increased Clq binding activity did not correlate with either an increased total white cell count of ESR. Measurement of Clq binding activity may be of value in serial monitoring of disease progress and response to treatment.
Hybridomas have been produced from mice immunized with human IgG. Culture supernates were assayed for the presence of antibody-producing cells by passive haemagglutination. Hybridomas producing antibodies to human kappa (kappa) and lambda (lambda) light chains have been cloned and grown as ascitic tumours in BALB/c mice. The antigen-binding characteristics of the monoclonal antibodies, contained in the ascitic fluid, were assessed by haemagglutination inhibition, ELISA and radioimmunoassay systems and by the binding of radiolabelled antigen in analytical flat-bed iso-electric focussing gels. One monoclonal anti-kappa reacted better with free than with combined kappa chains; for another the reverse was true. Antibody fractions separated by DEAE chromatography of ascitic fluids were coupled to ox red cells with chromic chloride and compared with polyclonal antibodies for the detection of cell-surface immunoglobulins.
In a controlled randomised clinical trial of 92 patients with surgically resected lung cancer, intrapleural BCG had no clear effect on survival. Adverse effects were insignificant.