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Biomedical subjects

M B Pepys

Publications and source records attributed to M B Pepys.

At least 289 records · Page 16Linked to original sources
PubMed1977

Complement in the induction of IgE antibody formation.

The IgE antibody response of NIH mice to ovalbumin was suppressed by in vivo complement depletion with cobra factor. This observation extends to IgE the finding that complement participates in thymus-dependent antibody formation. Control mice producing IgI anti-ovalbumin antibody after boosting all developed marked peripheral eosinophilia, whereas mice in which the IgE antibody response had been suppressed by cobra factor did not. Administration of cobra factor itself had no effect on peripheral eosinophil levels.

Animals↗
PubMed1977

Enumeration of lymphocyte populations in whole peripheral blood with alkaline phosphatase-labelled reagents. A method for routine clinical use.

An improved method is described for the enumeration of lymphocyte surface markers in whole peripheral blood using reagents labelled with alkaline phosphatase. A suspension of washed whole blood is exposed to the labelled reagents and then smeared on slides. Endogenous peroxidase in monocytes is detected by the diaminobenzidine reaction amplified by osmication, and this identifies more cells than are recognised as monocytes by morphological criteria in Romanovsky-stained films. Lymphocytes are identified as peroxidase-negative mononuclear cells and those binding alkaline phosphatase-labelled reagents are demonstrated by treating the smears with naphthol ASMX phosphoric acid and fast red TR salt. By avoiding the loss of lymphocytes which is inevitable in any procedure for isolation of mononuclear cells from the blood, and by permitting elimination of monocytes from the counts, this method enables the proportion and absolute number of different circulating lymphocyte populations to be accurately enumerated. In the peripheral blood of seventeen normal individuals alkaline phosphatase rabbit F(ab)'2 anti-human immunoglobulin stained the following numbers (mean +/- s.d.) of lymphocytes, 9-0 +/- 1-5%, 214 +/- 66/microliter (B cells), and specific rabbit anti-T-cell serum followed by alkaline phosphatase goat F(ab)'2 anti-rabbit immunoglobulin stained 77 +/- 3%, 1846 +/- 488/microliter (T cells). The method, which is applicable to any surface marker which can be detected on living cells in suspension with a soluble reagent, provides permanent preparations which are counted in an ordinary light microscope and permits the use of counterstaining to reveal cellular morphology. Provided that appropriate specific reagents are available it is therefore suitable for routine clinical application.

Adult↗
PubMed1977

Isolation and study of murine C3.

C3 was isolated in purified form from fresh murine serum and plasma by precipitation as euglobulin followed by removal of other proteins on immunoadsorbent columns bearing antibodies raised against specifically C3 depleted serum. Recovery was 30--55% and the C3 was all in its native form. Functional activity was demonstrated by fixation of the C3 on EAC142gp cells and by interaction with lymphocyte C3 receptors. Mouse C3 in plasma and after isolation had a molecular weight of 240,000. Its cleavage by classical pathway and cobra factor induced C3 convertases and by trypsin yielded a major conversion product with molecular weight not less than 210,000, the electrophoretic mobility of which differed when it was generated from isolated C3 rather than in plasma.

Animals↗
PubMed1976

Enumeration of immunoglobulin-bearing lymphocytes in whole peripheral blood.

A new method is described for the detection by immunofluorescence of lymphocyte populations in whole peripheral blood. Lymphocytes are identified by their lack of intracellular peroxidase, and the absolute number of different populations can be accurately enumerated by avoiding procedures for isolating mononuclear cells before fluorescent staining. Among twenty-two normal individuals the mean +/- s.d. percentage and absolute number of lymphocytes with stable surface immunoglobulin were as follows: IgM, 8-1+/-2-3%, 142+/-60/mu1; IgD,8-9+/-2-2%, 212+/-85/mu1;IgA, 2-2+/-1-0%, 41+/-24/mu1; IgG, 2-3+/-1-6%, 60+/-47/mu1. It was confirmed that the detection of true IgG-bearing lymphocytes depends on washing the blood at 37degrees before staining or the use of F(ab)2 anti-IgG antibodies. The proportion of lymphocytes stained by whole IgG polyvalent anti-immunoglobulin antibody, which detects both true immunoglobulin-bearing lymphocytes (B cells) and Fc receptor cells was constant (20-5+/-1-0%) both in and between individuals, but the absolute numbers (380+/-117/mu1) varied with the lymphocyte count.

Adult↗
PubMed1975

Effects of human chorionic gonadotropin preparations on complement in vitro.

The effects on complement in vitro by several commercial preparation of human chorionic gonadotropin (HCG) were investigated. These preparations were demonstrably anticomplementary and produced marked conversion of the third component of complement (C'3). However, detailed analyses showed that the anticomplementary activity was because of the presence of immunoglobulins in the HCG preparations. In view of the known modifying effects of C'3-reactive agents on skin allograft survival and of antigen-antibody complexes on lymphocyte transformation, it may be necessary to reconsider previous work on the immunosuppressive effects of HCG preparations.

Absorption↗
PubMed1975

A new immunoassay for C3. Application of the cell-linked antigen radioactive antibody (CLARA) technique.

The cell-linked antigen radioactive antibody (CLARA) method of immunoassay was applied to the C3 component of the complement system. C3 from whole complement was fixed on erythrocytes sensitized with IgM antibody. The IgG1 fractions of monospecific sheep anti-C3 were labelled with 125I and measurement of their specific binding to C3-bearing erythrocytes was used to quantitate the relative amount of fixed C3. Competititive inhibition of this specific binding was used to assay fluid phase C3. 0.3-0.6mug/ml of murine C3 were detected in the supernatant fluid of in vitro cultures of mouse spleen cells.

Animals↗
PubMed1975

Complement dependence of localisation of aggregated IgG in germinal centres.

In vivo decomplementation of mice with cobra factor completely prevented trapping of aggregated human IgG within splenic germinal centres. Observations of the intrasplenic position of the aggregated material within 8 hr of its injection into normal and decomplemented mice suggest that the early phase of localisation in germinal centres depends on binding to lymphocyte C3 receptors.

Animals↗
PubMed1975

Studies in vivo of cobra factor and murine C3.

The effect of the isolated C3-cleaving factor (CoF) of cobra venom on murine C3 in vivo and in vitro was studied. Optimal quantities of 100-200 units (0.5 minus 1.0 mg) of CoF per kg administered to mice by intraperitoneal injection in divided doses caused plasma C3 levels to fall to less than 5 per cent of normal from 1 to at least 4 days afterwards. Passive anti-CoF serum promptly abrogated the in vivo plasma C3 depletion, and under optimal conditions C3 levels reached 50 per cent of normal after approximately 15 hours. Injection of as little as 20 mug per mouse of CoF in saline induced a precipitating anti-CoF antibody response which prevented subsequent depletion of plasma C3 by CoF. The in vivo half-life of 125I-labelled CoF in normal mice estimated by whole body elimination and clearance from the blood was 24 hours. The presence in vivo of antibodies to CoF caused rapid clearance from the blood and elimination of 125I-labelled CoF, and also localization of some CoF in the spleen, liver and kidneys.

Animals↗
PubMed1974

Role of complement in induction of antibody production in vivo. Effect of cobra factor and other C3-reactive agents on thymus-dependent and thymus-independent antibody responses.

In an in vivo study in mice, suppression by the C3-cleaving protein of cobra venom (CoF), and other C3-reactive agents (zymosan, aggregated IgG, anti-C3 antibodies, and type III pneumococcal polysaccharide) of the thymus-dependent antibody responses to sheep erythrocytes, ovalbumin, and human IgG was demonstrated. The thymus-independent antibody response to polyvinyl-pyrrolidone was however unaffected by CoF. These and other published observations suggest that there may be a requirement for functional C3 in induction of thymus-dependent but not thymus-independent antibody production. A model for the role of C3 in lymphocyte cooperation is proposed based on these data analyzed in the light of existing knowledge of this process. It is postulated that fixed C3 interacting with macrophage See PDF for Structure and B-cell C3 receptors might enhance or facilitate T-dependent presentation of antigen to B cells.

Animals↗