Search PubMed⌕ Search

Biomedical subjects

P Rouger

Publications and source records attributed to P Rouger.

At least 91 records · Page 5Linked to original sources
PubMed1995

Flow cytometric monitoring of allergen induced basophil activation.

Human basophils express many clustered differentiation antigens (CD), including CD45; however, none are specific for these cells. In a previous study, we described a two-color immunofluorescence procedure, employing antibodies to CD45 and IgE for the cytometric evaluation of basophils. In the present work, we show that when sensitized basophils are stimulated by allergenic preparations, they demonstrate an upregulation of CD45 as well as a decrease in anti-IgE binding. Since CD45 antigen modulation was observed with all aeroallergens tested and the decrease in IgE expression varied with allergenic preparations, the measurement of CD45 upregulation was used to evaluate basophil activation. Using this approach, reproducible results were observed when atopic patients were tested at different time intervals. In addition, we show that the upregulation of CD45 on allergen stimulated basophils is a very rapid phenomenon that is observed after a few minutes and that this rapid flow cytometric method can also be used for investigations on nonallergenic mediators of basophil stimulation such as calcium ionophores.

Adult↗
PubMed1995

[Immunologic hemolytic anemia. From autoimmunity to anti-medication immunization].

The serological investigation of auto-immune hemolytic anemias based on the direct antiglobulin test, the study of the serum and the eluate allows a classification of the auto-immune hemolytic anemia which is still valid and correlates well with the clinical features. The use of new techniques should increase the sensitivity of the tests but also stress the problem of the frontier between physiological and pathological states. The use of monoclonal antibodies of defined specificity would be an useful tool for the immunohematological classification of the auto-immune hemolytic anemias. The addition of new therapeutical means should improve the prognosis of these anemias. The increasing consumption of drugs and the development of the investigations of the adverse reactions including the hemolytic anemias have allowed the emergence of new pathogenic concepts. The gravity of the clinical evolution of some of these immune hemolytic anemias stress the necessity of an adequate therapeutic survey and the development of new means of diagnostic. The clinicians should be aware of the possibility of cross reactivity for drug dependent antibodies with other components of related chemical structure.

Anemia, Hemolytic, Autoimmune↗
PubMed1995

The future of blood groups and other markers in reference laboratories.

Erythrocyte blood group-reference laboratory activities have to develop in accordance with new scientific knowledge brought by molecular biology. Reference laboratories will have to use immunology as well as molecular biology for a long time yet; both approaches are complementary. Recombinant cells expressing specific antigens will thus be used in parallel to red blood cells with selected phenotype combinations. To be efficient, Reference laboratory activities must be performed together with research and education activities with a view to spreading knowledge within a national network.

Blood Group Antigens↗
PubMed1994

[Failure mechanisms in the transfusion process. Importance of anticipatory operational safety analysis].

The methods used for the safety previsional analysis of operations represent an interesting set of tools to follow the so-called transfusion process, defined as all the steps from donors sensitization to recipients follow-up. FMECA (Failure Mode Effects and Criticality Analysis) can be used as a prevention tool, independently of any dysfunction in the process. Of course, it can also be used following a failure, in order to analyse its causes and to apply specific corrections. Operation safety, quality insurance, epidemiologic surveillance and safety monitoring act in synergy. These three aspects of transfusion safety constitute a dynamic system.

Blood Banks↗
PubMed1994

[Preventing deficiencies in the transfusion process].

The methods of system reliability analysis represent an interesting set of tools used to follow the so-called "transfusion process", defined as all the steps from donors sensitization to recipients follow-up. FMECA, (Failure Mode Effects and Criticality Analysis), can be used as a prevention tool, independently of any dysfunction in the process. Of course, it can equally be used following a failure, in order to analyse the causes and to apply the specific corrections. Quality insurance, system reliability analysis, epidemiologic surveillance and safety monitoring operate in synergy. These three issues pertaining to transfusion safety constitute a dynamic system.

Blood Banks↗
PubMed1994

[Immunologic risks of blood transfusion and public health].

The general objective is the study, through scientific approaches, of the main components of immunological risks linked to red blood cell transfusions, as well as their consequences, in order to define precise rules for prevention, taking into account that 2,700,000 units were transfused in 1992. To reach this general aim, five intermediary objectives have to be achieved: 1) The sentinel study of the methodology used to collect information about transfusion accidents, as well as their identification and their early clinical expression; 2) The analysis of the occurrence mechanisms of incompatibilities and transfusion accidents; 3) The up-date definition of post-transfusion alloimmunization, in particular regarding 3 parameters: a) the immunogenicity of the different erythrocyte antigens, that will have to be reassessed; b) the modes of occurrence of post-transfusion anti-erythrocyte alloimmunization; c) the different types of chronology in the appearance and the persistence of anti-erythrocyte antibodies. 4) The search for significant criteria in order to assess the immunopathological correlations of the consequences of antigen-antibody conflicts; 5) The elaboration of the principles for tests evaluation and identification of the techniques linked to blood groups and the study of anti-erythrocyte antibodies.

Blood Group Incompatibility↗
PubMed1994

Purification and biological activity of a recombinant human erythropoietin produced by lymphoblastoid cells.

A recombinant human erythropoietin (rH-EPO) was obtained from the culture supernatants of human B-lymphoblastoid cells transfected by the human EPO gene. rH-EPO was purified by a two-step method based on immunoaffinity and ion exchange chromatography. The first step was achieved by an anti-EPO monoclonal antibody (Mab). This Mab, immobilized on Sepharose 4B, allowed a 410-fold purification of the protein. The second step consisted of ion exchange chromatography on DEAE Sephacel. The combination of these two steps results in a highly purified rH-EPO with a global yield of about 50%; the specific activity of the protein was 176,000 IU/A280. The NMR spectrum was characteristic for a well structured, single-conformation protein. The purified protein was analyzed by SDS-PAGE and isoelectric focusing. The biological activity of purified rH-EPO was measured in vivo, by the incorporation of 59Fe into red blood cells (RBC) of polycythemic mice and in vitro by the proliferative response of an EPO-dependent cell line. The purified protein expressed in lymphoblastoid cells of human origin had the same biological activity as that of urinary EPO and rH-EPO produced in other mammalian cells.

Amino Acid Sequence↗
PubMed1993

Purification of human IgG4 subclass with allergen-specific blocking activity.

Blocking antibodies (bAb) induced by allergen immunotherapy are restricted to the IgG1 and IgG4 subclasses, with IgG1 predominating early and IgG4 coming later. Study of IgG4 bAb has been limited, in part, by the absence of a method to purify IgG4. We describe a rapid immunoaffinity chromatographic method for the purification of that subclass from whole serum. Starting serum (TR) contained 90 micrograms/ml Dactylis glomerata (orchard grass) pollen (DGP)-specific IgG4, measured by indirect ELISA. The blocking activity of TR was assayed in vitro on IgE-sensitized human basophils. Immunoadsorption on a strong-binding anti-IgG4 monoclonal antibody (mAb) removed about 90% of the total and allergen-specific IgG4 and nearly all of the blocking activity from TR. An IgG4-rich fraction was then obtained by absorption of several small volumes of TR on a weak-binding anti-IgG4 mAb column at neutral pH followed by elution with glycine-HCl buffer. The pooled eluates contained 82% IgG4, amounting to a 65-fold purification of the serum IgG4; the yield was approximately 30%. Nearly all the DGP-specific antibody was in the IgG4 component of the eluate. The blocking activity of the eluate was approximately equal to that of TR. Immunoblot patterns with the eluate and with TR on SDS-PAGE of DGP were nearly identical. This method thus provides a fully active, relatively pure IgG4 blocking antibody. Moreover, the results reinforce the importance of using a well-chosen mAb when purifying proteins by immunoaffinity chromatography.

Adult↗
PubMed1993

Flow cytometric evaluation of human basophils.

The expression of CD45 and IgE cell surface antigens on human leucocytes was studied by flow cytometry. More than 80% of sorted cells that expressed low CD45 (CD45dim) and high IgE (IgEbright) antigen site density were identified as basophils. Immunomagnetic depletion of the CD45dim-IgEbright cell subset by a biotin-coupled anti-IgE antibody and streptavidin-coated magnetic beads was greater than 90%, and more than 80% of cells binding significant numbers of beads exhibited the morphological characteristics of basophils. Interestingly, when the cell staining was performed in the presence of calcium and magnesium, we observed a significant increase of CD45 and an equivalent decrease of IgE cell surface expression, as well as an IgE concentration dependent diminution of the number of CD45dim-IgEbright cells.

Antibodies, Anti-Idiotypic↗
PubMed1993

Circadian rhythms of circulating NK cells in healthy and human immunodeficiency virus-infected men.

Antiviral immunity involves NK cells, which circulate rhythmically every 24 hours. We have investigated circadian and 12-hour rhythms in the peripheral count of circulating NK cells in 15 men infected with human immunodeficiency virus (HIV) and 13 healthy controls. We analyzed three phenotypes using double-labeling with monoclonal antibodies and flow cytometry assessment: CD3- CD16+, CD3-CD57+, and CD2+CD3-. A statistical validation of time-dependent differences was achieved if significance (p < 0.05) was validated both with analysis of variance and cosinor. The circadian rhythm had a similar asymmetric waveform for the three phenotypes and is homogeneous on an individual basis. The circulating NK cell count peaked in the early morning and was low at night. A circadian rhythm and a circahemidian harmonic characterized all phenotypes in healthy subjects. We considered two groups of HIV-infected men: those who were asymptomatic (eight) and those with acquired immune deficiency syndrome (AIDS) (seven). Circadian changes in NK cell count were similar in both subgroups and in healthy controls. The circadian pattern was also consistent among individual patients. Asymptomatic HIV-infected men (early-stage disease) exhibited more pronounced 12-hour rhythmicity than did patients with AIDS or controls. The circulation of NK cells does not appear to share the same synchronizer(s) as other circulating T- or B-lymphocyte subsets. Thus, HIV infection gradually abolished circadian rhythmicity in circulating T and B cells, whereas it did not disturb that in NK cells.

Acquired Immunodeficiency Syndrome↗