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Biomedical subjects

I Mota

Publications and source records attributed to I Mota.

At least 73 records · Page 4Linked to original sources
PubMed1986

Antigenic competition in IgE antibody production. III. Suppressive effect on Th and B cells.

An adoptive cell transfer system was utilized to evaluate the site of action of the suppressive mechanism involved in antigenic competition in IgE antibody production. Carrier-primed (OA) and hapten-primed (DNP-KLH) spleen cells were transferred to syngeneic irradiated recipients that were challenged with a heterologous conjugate (DNP-OA). To study the effect of antigenic competition on T and B cells, donor mice of one or the other cell type received in addition the competitor antigen (Asc) at immunization. The adoptive secondary IgE anti-DNP antibody response was suppressed in both situations. This effect could not be attributed to transfer of Asc-primed cells. Irradiation of donor mice before immunization with the two antigens abrogated the suppressive effect. These results indicate that both Th and B cells primed to the test antigen were affected by antigenic competition.

Animals↗
PubMed1985

Antigenic competition in IgE, IgG1 and IgG2 antibody production in the mouse.

A comparative study of the effects of antigenic competition on the IgE, IgG1 and IgG2 antibody production was performed in mice immunized with two unrelated antigens. These antigens were injected as a mixture or in different sites. In addition, the groups of mice received one or three boosters of one or both antigens. The passive cutaneous anaphylaxis titres obtained in several bleedings showed a suppression of IgG1 and IgG2 antibody responses only in the groups injected with the two antigens in the same site, independently of antigenic boosters. The IgE antibody response was diminished when the antigens were given in a mixture, but this effect disappeared after a second booster. In contrast, groups injected with antigens separately started to show a suppressed response only at this time.

Anaphylaxis↗
PubMed1984

Isotype of lytic antibodies in serum of Chagas' disease patients.

The isotype of anti-Trypanosoma cruzi lytic antibodies present in sera obtained from patients with the chronic phase of Chagas' disease was determined. Serum samples were submitted to gel filtration in Sephacryl S-200, ion exchange chromatography in DEAE-cellulose, affinity chromatography with protein A and immunoadsorption with anti-human IgG-Sepharose. The results of these experiments showed that human anti-T. cruzi lytic antibodies are mainly located in the IgG isotype probably in the IgG1 and IgG2 subclasses.

Chagas Disease↗
PubMed1983

Isotype of antibodies responsible for immune lysis in Trypanosoma cruzi infected mice.

Serum obtained from mice infected with Trypanosoma cruzi have antibodies able to induce immune lysis in presence of complement. Gel filtration in Sephadex G-200 and affinity chromatography with rabbit anti-mouse IgG and protein A-Sepharose showed that the antibodies responsible for the immune serum lytic activity are exclusively located in Ig of IgG isotype, including IgG1, IgG2a, IgG2b and probably IgG3. It is suggested that antibodies responsible for protection against T. cruzi infection and antibodies responsible for immune lysis are the same.

Animals↗
PubMed1983

Homocytotropic and heterocytotropic activity of mouse IgG1 antibodies.

Mouse anti-ovalbumin antibodies were isolated by affinity chromatography and fractionated in a column of protein A-Sepharose. Three peaks were obtained: peak I that did not bind to protein A, peak II eluted with 0.5 M NaSCN and peak III eluted with 2.0 M NaSCN. Peak I and peak II contained IgG1 but no detectable IgG2 or IgG3, whereas peak II contained IgG2 and IgG3 but no detectable IgG1. Peak I, but not peak II, showed heat-resistant passive cutaneous anaphylactic (PCA) activity in rats, which was absorbed by anti-IgG1 serum but not by anti-IgE. Both peak I and peak II showed heat-resistant PCA activity in mice, that was absorbed by anti-IgG1. Peak III showed PCA activity in guinea pigs but not in mice or rats. These findings suggest that mouse IgG1 can be divided into 2 populations that differ in physicochemical and biological properties.

Animals↗
PubMed1982

Two biologically different mouse IgG1 antibodies.

Isolated mouse antibodies were submitted to affinity chromatography with protein A. Three peaks were obtained: peak I that did not bind to protein A, peak II eluted with 0.5 M NaSCN and peak III eluted with 2.0 M NaSCN. Peak I and peak II contained IgG1 but no detectable IgG2 or IgG3, whereas peak III contained IgG2 and IgG3 but no detectable IgG1. Peak I, but not peak II, showed heat-resistant passive cutaneous anaphylactic (PCA) activity in rats which was absorbed by anti-IgG1 antiserum but not by anti-IgE. Both peak I and peak II showed heat-resistant PCA activity in mice, that was absorbed by anti-IgG1 serum. Peak III showed PCA activity in guinea pigs but not in mice or rats. These findings suggest that mouse IgG1 can be divided into 2 populations that differ in their affinity for protein A and in their PCA activity.

Animals↗
PubMed1982

Antigenic competition in IgE antibody production. II. Effect of cyclophosphamide.

The effects of cyclophosphamide (CY) on antigenic competition in IgE antibody production were studied in mice treated with the drug on different days and immunized with a mixture of two non-related antigens. Injection of 100 mg of CY/kg of body weight 3 days before or 6 days after immunization resulted in a partial or total recovery of the IgE, but not of the IgGl antibody response to the test antigen. In contrast, when the same dose was given together or 3 days after immunization both responses were much more suppressed than in untreated animals. This same effect was obtained when a higher concentration (200 mg/kg) of cyclophosphamide was injected on day--3. When a different antigenic system was tested, the suppressive effects of competition in IgGl antibody production were also abolished after CY treatment. These results seem to provide further evidence for an important role of suppressor T cells in the mechanism of antigenic competition.

Animals↗
PubMed1980

Antibody suppression in mice infected with Nippostrongylus brasiliensis.

A/SN mice infected with N. Brasiliensis showed depressed anti-DNP antibody responses following immunization with DNP-Asc in alum. The immunosuppression was only observed when infection preceded immunization by between 2 and 7 days, and was not achieved when the interval was extended to 10 days. The suppression lasted at least 50 days, and affected IgE levels more than IgG1 or IgG agglutinating anti-DNP antibodies. A high dose of infective larvae (500-1000 per mouse) was necessary to induce suppression. Use of low dose irradiation indicated a parasite-induced radiosensitive component of the mouse immune system which negatively regulated the anti-DNP IgE response. These results suggested that the parasite could induce suppression in an analogous manner to sequential antigen-induced suppression (AIS).

Animals↗
PubMed1980

Antigenic competition in IgE antibody production. I. Establishment of parameters involved in primary and secondary responses.

Antigenic competition was demonstrated in IgE antibody response in mice immunized with ovalbumin or DNP-ovalbumin associated with several non-related proteins: DNP-Ascaris, DNP-keyhole limpet haemocyanin or Ascaris. Simultaneous injection of two antigens caused a suppression of IgE antibody production to the test antigen, IgG1 antibody formation being only diminished under certain conditions. Competition was dose-dependent and effective only in the primary response. However, the secondary response could be also partially suppressed if the competitor antigen was given in both first and second antigenic stimulation. Competition was abolished by irradiation prior to immunization.

Animals↗
PubMed1979

In vitro cellular immunity in Chagas' disease.

In vitro delayed hypersensitivity was studied in patients with either the chronic or the indeterminate phase of Chagas' disease. Normal healthy individuals were used as controls. The leucocyte migration inhibition test was applied using an antigen an extract of culture forms of T. cruzi or an extract of normal rat heart. The results showed that patients with the chronic phase of the disease reacted significantly with both antigens, whereas most patients with the indeterminate phase did not react with heart antigen and only five out of fourteen (35%) reacted with T. cruzi antigen. It is suggested that these individuals may represent patients about to develop the chronic phase of the disease. The relevance of these findings to the immune mechanism influencing the onset of the chronic phase of Chagas' disease is discussed.

Adolescent↗
PubMed1976

Homologous passive cutaneous anaphylaxis (PCA) in mice and heterologous PCA induced in rats with mouse IgE.

A study was made of the effect of anit-histamine, antiserotonin and of different anti-anaphylactic drugs on PCA reactions induced in mice with IgG1 or IgE. Further, using the ability of mouse IgE to sensitize rat mast cells, a comparative study was also made of PCA reactions induced in mice and rats with mouse IgE. Antihistamines produced a partial inhibition of PCA reactions induced in mice with mouse IgG1 or IgE and in rats with mouse IgE whereas antiserotonin inhibited PCA reactions induced in rats with mouse IgE, but had no effect on PCA reactions induced in mice with mouse IgG1 or IgE. The simultaneous use of antihistamine and antiserotonin resulted in a total inhibition of PCA reactions induced in mice with IgG1 and in a marked but not total inhibition of PCA reaction due to IgE; PCA reactions induced in rats with mouse IgE were totally inhibited. Compounds known to change the intracellular level of cyclic AMP were found to have little or no effect on PCA reactions induced in mice with either IgG1 or IgE in spite of producing a complete marked inhibition of PCA reactions induced with mouse IgE in rats. Diethylcarbamazine or disodium cromoglycate were also very effective inhibitors of rat PCA reactions induced with mouse IgE although having no effect on PCA reaction induced in mice with this same antibody or with IgG1. Thus, in spite of sharing common mediators released from the same type of target cell sensitized with the same type of antibody, PCA reactions induced in mice and rats with mouse IgE reacted very differently to the pharmacological effect of most of the drugs tested. This fact seems to indicate that the physiological mechanism operating in mouse mast cells are different from those operating in rat mast cells.

Animals↗
PubMed1975

The effect of a synthetic double-stranded RNA on IgC1 and IgE production by guinea-pigs. A comparative study with lipopolysaccharide.

The effect of synthetic complexes of polyribocytidylic acid (poly-IC) on the production of homocytotropic antibodies by guinea-pigs was studied. It was observed that poly-IC has a definite adjuvant effect on the production of both IgG1 and IgE. The adjuvant effect was present when poly-IC was injected 24 hours after the antigen, but was absent when the polynucleotide was injected 48 hours after the antigen. In comparison with lipopolysaccharide (LPS) the adjuvant effect of poly-IC was weaker, more than 0.5 mg/kg of this polynucleotide being required to show an adjuvant effect, whereas only 20 mug/kg of LPS was enough to show a positive adjuvant effect. Furthermore, considerably less antibody was detected in the animals stimulated with the polynucleotide.

Adjuvants, Immunologic↗