Search PubMed⌕ Search

Biomedical subjects

R R Coombs

Publications and source records attributed to R R Coombs.

At least 109 records · Page 6Linked to original sources
PubMed1980

Receptors on guinea-pig erythrocytes specific for cell-bound fourth component of human complement (C4).

Guinea-pig erythrocytes have receptors for heterologous (human and rabbit) complement activated by the classical pathway on cell surfaces. This was shown in the present study by rosette-forming reactions of guinea-pig erythrocytes and human lymphocytes or sheep erythrocytes pre-treated with antibody and human R3 complement. The binding is temperature-dependent and is enhanced by treating the guinea-pig erythrocytes with neuraminidase. The receptors were shown to be specific for C4 by inhibition tests employing a range of anti-human complement antibodies (including anti-Clq, -Cl inhibitor, -C4, -C2, -C3 and -C3b inactivator). Of these reagents, only anti-C4 inhibited the receptor activity, indicating that the guinea-pig erythrocyte C4-receptors differ from those on lymphocytes, monocytes, polymorphonuclear leucocytes and human erythrocytes which are reported to react with both C3b and C4b. In contrast to the strong affinity observed for heterologous C4, guinea-pig erythrocytes appear to react very weakly, if at all, with homologous C4.

Animals↗
PubMed1980

Natural cytotoxicity in the guinea-pig: the natural killer (NK) cell activity of the Kurloff cell.

Natural killer (NK) cell activity was found in the various lymphoid compartments of the normal guinea-pig, prominent in the spleen and absent in the thymus. Oestrogen treatment, which increased the Kurloff cell population in blood, spleen and thymus, did not alter NK cell activity in blood and spleen but markedly augmented the lytic capacity of the thymus. Rosetting reactions and selective depletion studies in normal and oestrogen-treated animals revealed the NK cells to belong to a small population of E+ Kurloff cells, some of which were Fc+ and others apparently Fc-. Some of these natural killer cells in the spleen also had receptors for C3 and carried Ig (probably cytophilic). In the lymph nodes, however, the NK cells were found to be E+ lymphocytes, again some of which were Fc+ and others Fc-.

Animals↗
PubMed1979

Do human B and null lymphocytes form a single immunoglobulin-bearing population?

Human "null" lymphocytes have been recognised because they lack T-lymphocyte membrane markers and the surface membrane immunoglobulin (smIg), detectable by direct immunofluorescence, which conventionally characterises B lymphocytes. But almost all null lymphocytes express smIg determinants which are demonstrable by the direct antiglobulin and mixed antiglobulin rosette tests. It is argued that the definition of a B lymphocyte should be extended to include the null cells which react in these tests. If the heterogeneity of the B-lymphocyte population is more widely recognized, the precise nature of human natural and antibody-dependent killer cells may become clearer.

Antibody Affinity↗
PubMed1979

A simplified procedure for measuring the class of anti-bacterial antibodies by mixed reverse passive antiglobulin haemagglutination (MRPAH).

A modified procedure is described for performing the MRPAH (mixed reverse passive antiglobulin haemagglutination) reaction as a simple micro-method to measure the classes of bacterial antibodies. This 'bacterial dilution procedure' gave results closely correlated with those obtained by the 'serum (sample) dilution procedure' previously reported and with great economy of materials, labour and time. The method was used to investigate human serum antibodies to Br. abortus and S. enteritidis and serum and secretory antibodies to Strep. mutans. The good reproducibility of the MRPAH reaction was demonstrated by re-examining brucellosis sera tested one year previously. MRPAH was sufficiently sensitive to demonstrate the small amounts of IgG and IgM antibodies to Strep. mutans in human colostrum and early milk. A rise of antibody levels in the different immunoglobulin classes G, A and M was readily demonstrated in sera from individuals with salmonellosis.

Animals↗
PubMed1979

Detection of protein A-like substances on haemolytic streptococci prior to use in mixed reverse passive antiglobulin haemagglutination (MRPAH).

Before mixed reverse passive antiglobulin haemagglutination tests (MRPAH) can be used to measure the class of bacterial antibodies, the bacteria have to be shown to be free of Protein A or Protein A-like substances on their surfaces. Two basic procedures have been examined: haemagglutination of red cells coated with immunoglobulin by the bacteria, and the MRPAH reaction itself to reveal absorption of purified gamma Fc by the bacterial suspension. The use of a purified gamma Fc component has proved successful in providing a sensitive test for the detection of Protein A-like substances on the surface of bacterial. In addition to both the Cowan and Wood strains of Staph, aureus, strains of haemolytic streptococci of groups A, C and G had Protein A-like substances on their surfaces. In contrast, strains of group B and group D, as well as Strep. milleri, had no detectable Protein A-like activity.

Absorption↗
PubMed1979

A solid-phase system (SPACE) for the detection and quantification of rotavirus in faeces.

This report describes the development of a solid-phase haemadsorption system using chromic chloride-linked, antibody coated erythrocytes. It is proposed to call this technique solid phase aggregation of coupled erythrocytes (SPACE). The system is suitable for the detection of virus antigens, such as from rotavirus infections, which are present in 'dirty' or 'mixed' preparations such as faeces, urine or exudates. The test uses microtitre U-form plates coated with specific antivirus antibody; faecal suspensions are added and virus or antigen allowed to adsorb. The plates are then washed and adsorbed antigens are detected by the addition of virus-specific IgG-coated erythrocytes. The resultant settling pattern is read in the same manner as a conventional haemagglutination test. The system is compared with electron microscopy and fluorescent antibody techniques.

Animals↗
PubMed1979

Detection of gonococcal antigens in urine by radioimmunoassay.

A method of detecting gonococcal antigens by solid-phase radioimmunoassay with radioactively labelled antibody is described. A specificity test has been developed that enables this method to be used to detect gonococcal antigens in urine sediments. When sediments from samples of urine from male patients with gonorrhoea were tested, 31 (74%) of 42 gave positive results, clearly distinguishing them from sediments from urine samples from men with non-specific urethritis, none of which was positive. Ten of 14 urine sediments from urine samples from women with gonorrhoea gave positive results, as did 3 of 18 sediments from urine samples from women patients without gonorrhoea. These experiments demonstrate that gonococcal antigens can be detected in urine by radioimmunoassay; the method could be useful in diagnosis if, after refinement, its sensitivity and specificity were to be increased.

Antibody Specificity↗
PubMed1979

In vitro complement activation by rabbit lymphocytes and thymocytes in autologous serum.

The activation of C3, previously demonstrated to occur during the isolation of lymphocytes from rabbit blood, has been investigated further by in vitro exposure of blood and lymph node lymphocytes and thymocytes to autologous serum. Activated C3 deposited on the lymphoid cell-surface was detected by (i) anti-C3, (ii) immune adherence reaction, and (iii) blocking of receptors for C3. An affinity shown by guinea-pig erythrocytes for activated complement was also investigated. Using EGTA, which inhibits the classical complement pathway while leaving the alternative pathway unaffected, it was shown that either pathway may be activated by rabbit cells depending on the temperature of incubation. The classical pathway was triggered at 4 degrees, probably by the reaction of cold auto-antibodies with lymphoid cell-surface determinants. At 37 degrees, however, comlement activation followed the alternative pathway in a similar manner to that reported by other workers with human lymphoblastoid cell lines.

Animals↗
PubMed1979

Receptors for activated C3 on thymus-dependent (T) lymphocytes of normal guinea-pigs.

In a survey of lymphocyte subpopulations in normal guinea-pig blood, lymph node, spleen, thymus and peritoneal cavity, a considerable overlap was observed between the percentages of C3-receptor bearing lymphocytes (CRL) and of thymus-dependent (T) cells in lymph nodes. Simultaneous rosette-formation reactions with sheep erythrocytes carrying rabbit complement (EAC) and papain-treated rabbit erythrocytes (a T-cell marker) revealed that 20--50% of the lymph node CRL were T lymphocytes. These experiments and others on cell suspensions depleted of Ig-bearing (B) lymphocytes showed that between 8 and 36% of lymph node T cells have complement receptors. The frequency of T-CRL in other lymphoid tissues was lower, representing between 0 and 8% of the T-cell population. The reaction of T-CRL and EAC was not inhibited by EDTA which is known to inhibit the C3 receptor activity on macrophages.

Animals↗
PubMed1979

Comparison of the direct antiglobulin rosetting reaction (DARR) and direct immunofluorescence (DIF) for demonstration of sIg-bearing lymphocytes in pigs, sheep and cattle.

Tests with untreated and trypsin-treated red cells (rbc) from a variety of species showed that anti-Ig-coupled pig RBC are good indicator cells for the study of ruminant blood sIg + lymphocytes by the DARR test; coupled donkey and rabbit RBC are suitable for investigating pig lymphocytes. The different species showed the following percentages of sIg + lymphocytes (M +/- SE) by direct immunofluorescence (DIF) and the direct antiglobulin rosetting reaction (DARR) respectively:pigs 9.2 +/- 0.7% and 16.3 +/- 1.2%; sheep 20.2 +/- 1.2% and 33.1 +/- 1.6%; Cattle 13.5 +/- 1.4% and 28.9 +/- 3.5%. The mean ratio of sIg + lymphocytes shown by the two tests (DARR/DIF) for each species was 1.80 +/- 0.08 for pigs, 1.73 +/- 0.7 for sheep and 2.15 +/- 0.18 for cattle. Preincubation of pig and sheep lymphocytes at 37 degrees for 1 h did not alter the proportion of sIg + lymphocytes detected by either test. Thus the DARR test reveals a further population of sIg + lymphocytes in addition to that detected by immunofluorescence, whose number is proportional to the B population as measured by DIF and whose sIg is intimately associated with the membrane.

Animals↗
PubMed1979

Anaphylactic sensitivity of guinea-pigs drinking different preparations of cows' milk and infant formulae.

Guinea-pigs have been given various preparations of cows' milk or infant formulae to drink in an investigation of the capacity of these milk preparations to stimulate per os anaphylactic sensitivity. The treatment, presumably heat, used to concentrate the 'Evaporated' whole cows' milks (three brands were tested) almost abolished their sensitizing capacity to beta lactoglobulin. The brand presumed to be most heated as judged by the degree of caramelization had also lost most of its sensitizing capacity to casein. Injected parenterally, the 'Evaporated' milk adequately sensitized to anaphylaxis. An infant formula, which in its spray dried form was only moderately sensitizing to both beta lactoglobulin and casein, lost most of this sensitizing capacity when processed to a liquid concentrate state. The manufacturing process for the liquid concentrate involved greater and more prolonged heating than required for the spray-dried form. The relevance of these findings in the guinea-pig to cows' milk protein intolerance in the infant and possibly also to cot death is discussed.

Anaphylaxis↗
PubMed1978

Characterization of the human natural killer (NK) cell in blood and lymphoid organs.

The human natural killer (NK) cell in peripheral blood is a non-thymus-dependent, (Fc+ C3-), Ig-bearing lymphocyte and is probably identical to the human K cell, although not requiring the Fc receptor, in contrast to the K cell, for the lytic process. The human NK cell in tonsil and lymph node, on the other hand, is a non-Ig- bearing T lymphocyte, lacking both Fc and C3 receptors.

Cell Migration Inhibition↗
PubMed1978

The detection of alloantibodies to subpopulations of human lymphocytes: an adaptation of the indirect anti-immunoglobulin rosetting reaction (IARR).

An indirect anti-immunoglobulin rosetting reaction (IARR) can be successfully used to detect alloantibodies to human lymphocytes. In this paper we describe an adaptation of the IARR which allows detection of alloantibodies to human lymphocyte subpopulations. Fluorescein labelled sheep red cells, as a T cell marker, are incorporated into the rosetting reactions and by looking for rosettes with two indicator cell types, sheep and ox, one can determine if the alloantibodies are reacting with T cells or non-T cells. This type of assay is more sensitive than a standard cytotoxic test and can detect non-cytotoxic antibodies. The results show that this rosetting assay with two types of indicator cell can be useful in the study of pregnancy anisera, particularly those that are thought to contain reactivity directed solely against non-T cells. These antisera probably recognise the human DR antigens which are thought to be equivalent to the rodent Ia antigens.

Animals↗
PubMed1978

Artefactual variations in the B and T subpopulations of rabbit blood lymphocytes depending on method of isolation, and blocking of C3 receptors due to in vitro activation of complement.

Marked differences were found in the proportions of lymphocyte subpopulations in rabbit peripheral blood depending on the techniques used for the purification of lymphocytes. Rosette-forming reactions were used to find the numbers of T lymphocytes, Ig-bearing cells and cells with receptors for C3 or IgG-Fc. Some of the methods used for lymphocyte separation altered the relative numbers of T and B lymphocytes, through a disproportionate loss of T cells. Other changes were due to in vitro activation of complement detectable by the presence of C3 on the lymphocyte cell-membrane and causing partial blocking of C3 receptors. Highest yields of lymphocytes were obtained from defibrinated blood treated with carbonyl iron to remove phagocytes and methyl cellulose to sediment erythrocytes. This procedure was accompanied by in vitro activation of complement, with the consequences mentioned. Complement activation was inhibited by taking the blood into either EDTA or citrate. As EDTA was cytotoxic for rabbit T lymphocytes, citrate was considered best although the resulting lymphocyte suspensions were contaminated with up to 25% granulocytes and monocytes owing to the inhibition of carbonyl iron uptake by the prior exposure to citrate.

Animals↗
PubMed1978

Early rheumatoid-like lesions in rabbits injected with foreign serum: relationship to localization of immune complexes in the lining tissues of joints and cellular content of synovial fluid.

Immune complex localization in joint tissues and white cell effusion into the joint space as well as synovial lesions are shown to occur in rabbits injected intravenously with bovine serum. Synovial lesions of one knee were found to be associated with immune complexes in joint tissues of the contralateral knee (because of the experimental design very few rabbits had both immunofluorescence and histology performed on the same joint). There was also a week correlation between moderate and gross synovial lesions and cellular effusions of the same joint. Cartilage proteoglycan depletion was seen in some injected animals and this was related to lining cell hyperplasia. Rabbits from different breeding colonies displayed different incidences of lesions suggesting an environmental or genetic influence on the development of rheumatoid-like lesions.

Animals↗
PubMed1978

The class of antibodies sensitizing bacteria measured by mixed reverse passive antiglobulin haemagglutination (MRPAH).

A test is described which is capable of differentiating and measuring by titration the individual classes of antibody reacting with a bacterial suspension. The serum or fluid under test is incubated with the bacteria which are then very well washed and added to indicator red cells linked with specific antiglobulin reagents. Sensitization of the bacteria by a particular class of antibody is shown by haemagglutination (passive) of the appropriate red cells. Agglutination of the bacteria themselves does not preclude an analysis. The reaction, which has been developed on a brucella system, has been designated Mixed Reverse Passive Antiglobulin Haemagglutination (or MRPAH for short).

Antibodies, Anti-Idiotypic↗
PubMed1978

Comparison of the direct antiglobulin rosetting reaction with direct immunofluorescence in the detection of surface membrane immunoglobulin on human peripheral blood lymphocytes.

Comparisons were made between the Direct Antiglobulin Rosetting Reaction (DARR) and Direct Immunofluorescence (DIF) in the detection of surface membrane immunoglobulin of human peripheral lymphocytes. The DARR was more sensitive and the results with this testing procedure (as opposed to those with the DIF) were not influenced by various treatments of the lymphocytes before testing, such as incubation in AB serum at +/- 4 degrees, incubation in serum-free medium at 37 degrees or short exposure to acetate buffer at pH 4.0. Again the DARR (as opposed to the DIF) gave essentially the same results whether the red cell-linked antiglobulin was IgG or the F(ab')2 preparation. With mixed rosetting for both T and SmIg+/- lymphocytes, there was only 1% or less null cells and only 5% or less lymphocytes rosetted with both marker red cells.

Antibodies, Anti-Idiotypic↗