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Biomedical subjects

G F Mitchell

Publications and source records attributed to G F Mitchell.

At least 199 records · Page 11Linked to original sources
PubMed1980

Accelerated rejection of Nematospiroides dubius intestinal worms in mice sensitized with adult worms.

After oral administration of infective third stage larvae (L3) of Nematospiroides dubius to young mice, intestinal worms persist for many weeks. However, in mice injected parenterally with N. dubius adult worms, the intraluminal intestinal infection arising after L3 administration can be terminated within 3 to 4 weeks. This accelerated rejection is seen in sensitized BALB/c mice (and (CBA/H X BALB/c)F1 mice) and in particular females, but has not been demonstrated in sensitized CBA/H mice. In female BALB/c mice, small numbers of living worms are more effective at sensitization than dead worms, intraperitoneal and subcutaneous implantations are both effective, and products from adult worms incubated in vitro (i.e. "excretory/secretory" (ES) products) will sensitize but only with very high doses in adjuvant. Using appropriate isolated antigen preparations, comparative immunoparasitological analyses in different mice should provide clues on the nature of host-protective immunities against intestinal nematode infections which are potentially chronic. From the present studies, two groups which differ most dramatically in the consequences of adult worm sensitization are young male CBA/H versus older female BALB/c mice.

Animals↗
PubMed1980

Hybridoma antibody immunoassays for the detection of parasitic infection: attempts to produce an immunodiagnostic reagent for a larval taeniid cestode infection.

Attempts have been made to produce discriminatory immunodiagnostic reagents for infections of sheep with the larval stages of Taenia hydatigena, Taenia ovis and Echinococcus granulosus. Using cells from mice hyperimmunized with T. hydatigena antigenic preparations for fusion, a hybridoma antibody which bound to T. hydatigena larval antigens, but not to T. ovis or E. granulosus larval antigens, was selected. A competitive radioimmunoassay using the labelled hybridoma antibody and a crude parasite antigen mixture was devised as an immunodiagnostic test for experimental T. hydatigena infection. Sera from sheep exposed to 1000 or more T. hydatigena eggs were unequivocally positive but sera from 2 sheep with a monospecific infection with T. ovis were also positive. Sera from E. granulosus-infected sheep were negative and, although the numbers of sera involved were small, such discrimination has not been achieved by previous serologic methods. The discussion emphasizes various difficulties which have been encountered in the development of highly sensitive as well as specific hybridoma-based immunodiagnostic reagents for the detection of larval cestode infections in sheep.

Animals↗
PubMed1980

Cutaneous leishmaniasis in mice: disease patterns in reconstituted nude mice of several genotypes infected with Leishmania tropica.

BALB/c mice differ from CBA/H, (CBA/H x BALB/c)F1 and C57BL/6 mice in being highly susceptible to infection with a particular isolate of the intramacrophage protozoan parasite, Leishmania tropica. This is true over a wide range of challenge doses of promastigotes administered intradermally although, at low doses, male BALB/c are able to restrict the rate at which cutaneous lesions increase in size. Resistance to infection in highly susceptible hypothymic nude (nu/nu) mice of CBA/H and C57BL/6 genotypes can be achieved readily with as few as 10(6) syngeneic lymphoid cells. In CBA/H.nu/nu mice, Lyl+2- cells in low dose cellular inocula appear to be involved in restoring resistance (i.e. rapid resolution of infection). Surprisingly, a proportion of BALB/c.nu/nu mice injected with syngeneic lymphoid cells are resistant and thus differ from intact BALB/c mice or non-reconstituted BALB/c.nu/nu mice. In keeping with a high efficacy of limited numbers of T cells following minimal reconstitution, the majority of nude mice implanted subcutaneously with allogeneic, irradiated, neonatal thymus grafts are resistant to L. tropica infection. Genetic features of the nude mouse, such as defect in skin, may contribute to the extraordinary potency of T cell reconstitutive manipulations. Evidence was obtained that BALB/c.nu/nu skin on BALB/c.nu/+ recipients did not support the development of lesions as readily as normal skin sites.

Animals↗
PubMed1980

Antibodies to Leishmania tropica promastigotes during infection in mice of various genotypes.

After intradermal injection of 10(7) promastigotes of a particular isolate of the intramacrophage protozoan parasite, Leishmania tropica, the development of disease (cutaneous lesions) is much more severe in BALB/c than in three other mouse strains, C57BL/6,C3H/He and CBA/H. Using fixed promastigotes and 125I-labelled protein A in a solid-phase radioimmunoassay (RIA), titres of antibody were shown to increase up to about day 50 of infection. However, titres were not markedly different in BALB/c mice compared with the other three resistant strains, although antibody levels were highest in sera from the diseased BALB/c mice at late time points. Using isotype-specific antisera in the RIA, and sera from the day 50 time point, the isotype distribution of anti-promastigote antibodies was not noticeably different in sera from mice of the four genotypes with IgG1 and IgG2a (+/- IgG2b) antibodies predominating. It is concluded that differences in susceptibility to disease in this murine model of cutaneous leishmaniasis do not correlate with any decrease or increase in any particular antibody response to the promastigote.

Animals↗
PubMed1980

Genetic studies in human and murine giardiasis.

Genetic markers were analysed in 48 adults who appeared to have a prolonged infection with Giardia lamblia. The frequency of ABO blood groups, Rhesus blood groups, and Gm phenotypes was similar to that in control subjects. However, there was a higher than expected frequency of HLA antigens A1 (observed 46 . 7%, expected 32%) and B12 (observed 47 . 8%, expected 25 . 8%) and a higher than expected frequency of the phenotypes A1/A2 and B12/B27. Genetic studies were also performed with inbred strains of mice showing relatively rapid (BALB/c) and defective (C3H/He) spontaneous elimination of Giardia muris. From analysis in backcross mice several genes appeared to influence susceptibility to prolonged infection with G. muris.

Adolescent↗
PubMed1980

An investigation of the antigens of Ascaris lumbricoides using a radioimmunoassay and sera of naturally infected humans.

Of 5 humans from an Ascaris lumbricoides(var. suum)-endemic area who were positive for Ascaris infection (past or current) when examined by a radioallergosorbent test (RAST) for serum immunoglobulin E, only 1 contained detectable levels of Ascaris specific serum IgG antibodies. These antibodies were not detectable when the radioimmunoassay was replaced with a precipitin assay. There was a wide ringe of molecular weights and isoelectric points of antigens in Ascaris body fluid (ABF) which reacted with antibodies in this infected human. However, unlike the IgE-binding ABF antigens, the IgG-binding ABF antigens were particularly evident in one area of molecular weight and isoelectric point. This human also had IgA and IgM to Ascaris antigens whereas the others had barely detectable amounts.

Animals↗
PubMed1980

Inhibition of murine reaginic antibody responses by nasal immunotherapy with modified allergen.

Optimal conditions were established for induction of reaginic antibodies to Lolium perenne pollen allergens in mice by intranasal dosing of allergens with Bordetella pertussis vaccine. This antibody response could be inhibited by pretreatment of the mice by nasal administration of 100 microgram of glutaraldehyde-modified L. perenne allergens 9 times in 3 weeks before priming, whereas native allergens, in doses of 5 microgram, did not inhibit an IgE response to subsequent priming. It was not possible to suppress an ongoing reaginic antibody response by intranasal treatment with either native allergens, or glutaraldehyde-modified allergens. Relevance to immunoprophylaxis of allergic disease is discussed.

Adjuvants, Immunologic↗
PubMed1980

Surface markers of a purified peritoneal eosinophil population from Mesocestoides corti-infected BALB/c male mice.

Eosinophils of approximately 95% purity were prepared from the peritoneal cavities of BALB/c male mice infected with larval cestode, Mesocestoides corti. The alloantigenic surface marker phenotype of this cell population was shown to be H-2+Ly4+Ly5+Lyt-1-,2-,3-Ly-6-,7-Ia-Thy-1-TL-. Two of four anti-Lyt-2 sera were positive when tested on purified eosinophils by using the Staphylococcus aureus protein A sheep erythrocyte rosetting method, but absorption studies indicated that this reaction was not due to anti-Lyt-2 antibodies. Eosinophils are therefore Lyt-2-, although some Lyt-2 sera contain additional eosinophil reactive antibodies. A proportion (20 to 40%) of the population of eosinophils was positive for the Fc receptor, but all were negative for the C3 receptor and for surface immunoglobulin.

Animals↗
PubMed1980

A mechanism to account for mouse strain variation in resistance to the larval cestode, Taenia taeniaeformis.

Mice of various inbred strains differ markedly in resistance to first infection with Taenia taeniaeformis. Hypothymic nude mice of relatively resistant (e.g. BALB/c) and relatively susceptible (e.g. CBA/H) genotypes are highly susceptible but both can be protected against infection by injection of serum from infected mice. Using differential pH elution of "immune serum" from protein A-Sepharose, evidence was obtained that a combination of the pH 6 eluate (enriched for IgG1 molecules) plus the pH 3 or 4 eluate (enriched for IgG2 molecules) was more effective than either eluate alone at transferring protection to nude mice. By using whole serum transfer techniques, the rate of appearance of "host protective serum activity" (presumably antibody) was shown to be increased in genetically resistant versus susceptible mouse strains. It is suggested that, in relatively resistant mouse strains, host protective antibodies prejudice the establishment (or subsequent survival) of larvae prior to the full expression of protective mechanisms in the establishing larvae. In keeping with a host-protective effect of an accelerated immune response early in infection, a high dose challenge with eggs actually resulted in lower infection levels in genetically resistant mouse strains such as BALB/c and C57B1/6. The proposed mechanism of immunologically mediated, genetically based variation in susceptibility to T. taeniaeformis should not influence the effectiveness of a model vaccine against first infection in all strains of mice.

Animals↗
PubMed1980

Preparation and surface labeling of murine eosinophils.

Eosinophilic polymorphonuclear leukocytes were isolated from the peritoneal cavity of BALB/c mice infected with the parasite Mesocestoides corti. Approximately 4 X 10(7) eosinophils (purity, 50%) could be harvested from each mouse. A high yield and purity of eosinophils was obtained from the peritoneal cells of infected male BALB/c mice using density centrifugation on a gradient of slightly hypotonic colloidal silica sol (Percoll). After initial irradiation of the mice to lower the lymphocyte contamination, subsequent density gradient (and where necessary sedimentation velocity) centrifugation yielded 10(8) eosinophils (purity > 95%) from six to eight mice. It was also possible to isolate small numbers of eosinophils (2 X 10(4) cells/minute, purity > 99%) without irradiating the mice. This could be achieved by separating the density gradient purified peritoneal cells by light-scatter on a Becton-Dickinson cell sorter (FACS II). Analysis of proteins extracted from eosinophils using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed a group of high molecular weight proteins (bwtween 250K and 160K) which were not as distinctive in the neutrophil profile. Surface labeling was performed, before the cell separation by using 125I and 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril. Only five 125I-labeled proteins were detected initially (all with apparent molecular weights > 50,000). No 125I appeared to be associated with actin under the conditions used for surface labeling. Four of the eosinophil surface labeled proteins corresponded to surface labeled proteins on neutrophils, but the major surface component of the eosinophils (MW 79,000) appeared to be smaller than the major neutrophil protein (MW 90,000).

Animals↗
PubMed1980

Antibody isotypes mediating antigen retention in passively immunized mice.

Antibody isotypes vary in their capacity to mediate retention of a readily catabolized protein antigen, human serum albumin (HSA) in spleen, popliteal lymph node (PLN) and hind foot. Hyperimmune anti-HSA mouse sera were separated into fractions highly enriched for IgM, IgG1 and IgG2 via differential elution from protein A-Sepharose. These fractions were used to immunize normal mice passively. Twenty-four hours later the mice were injected with radio-iodinated HSA into the hind footpad. When the amount of HSA retained in the spleen 6 days later was determined, the potency of various antibody fractions to mediate retention could be ranked IgG2=IgG1 > IgM. The amount of HSA retention mediated by various fractions correlated well with autoradiographic evidence demonstrating localization of HSA in splenic follicles. The localization pattern in PLN was similar to the spleen except that the IgM-containing fraction mediated follicular localization of HSA to a considerable degree. In tendons of the hind foot, IgG1 mediated HSA retention five times better than IgG2 or IgM fractions. The amount of radioactivity found in the liver varied inversely with HSA retention in other locations. The results demonstrate differences in antibody isotype requirements for antigen localization in spleen, regional lymph node and collagenous sites of the hind foot.

Animals↗
PubMed1979

Attempts to immunise rats and mice against infection with fasciola hepatica using antigens prepared from taenia hydatigena.

Attempts were made to immunise rats and mice against infection with F. hepatica by oral dosing with T. hydatigena eggs, or by vaccination with various T. hydatigena antigen preparations. These antigens included extracts from T. hydatigena cysticerci and cyst fluid, and antigens collected during short-term (48 h) and long-term (14 days) in vitro cultivation of larvae. Immunity was assessed by the numbers of F. hepatica recovered from the challenge infection in rats, and the mortality rates of infected mice. None of the immunisation regimes with T. hydatigena antigens induced consistent, significant immunity. This was in contrast to the high level of immunity shown by rats dosed orally with F. hepatica metacercariae four weeks prior to challenge infection.

Animals↗
PubMed1979

Identification of differences between the surface proteins and glycoproteins of normal mouse (Balb/c) and human erythrocytes.

The topography of the external surface of the Balb/c mouse erythrocyte has been investigated and compared to the human erythrocyte by using a series of protein radiolabeling probes. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the pattern of Coomassie Blue stained proteins was very similar for mouse and human erythrocyte ghosts, as was the distribution of radioactivity in protein bands after lactoperoxidase catalyzed radioiodination. The mouse erythrocyte glycoproteins identified by periodic-acid-Schiff and 'Stains-All' reagents, sialic acid analysis of gel slices, binding of 125I-wheat germ agglutinin and 125I-concanavalin A to the gels, and glycoprotein radiolabeling techniques, differed markedly from the sets of proteins labeled by radioiodination, and also differed from the human erythrocyte glycoproteins. Instead of the PAS I to PAS IV series of sialoglycoproteins characteristic of human erythrocytes, the mouse erythrocyte possesses a broad band of sialoglycoproteins with several peaks ranging in mol wt from 65,000 to 32,000. The same group of sialoglycoproteins were labeled by the periodate/B3H4-technique specific for terminal sialic acid, and the galactose oxidase/B3H4-method (plus neuraminidase) specific for galactosyl/N-acetylgalactosaminyl residues penultimate to sialic acid. These results emphasize the necessity to employ a variety of protein radiolabeling probes based on different labeling specificities, to study the membrane topography of cells which are poorly understood compared to the human erythrocyte membrane.

Animals↗
PubMed1979

Fasciola hepatica: attempts to induce protection against infection in rats and mice by injection of excretory/secretory products of immature worms.

In vitro excretory/secretory products of 4-week (immature) and 8-week-old (mature) Fasciola hepatica parasites, derived from rats, were injected together with adjuvant into naive rats and mice. Resistance to infection was assessed in rats by counting adults in the bile ducts at 9 weeks, or in mice by recording deaths after oral challenge with a high dose of viable metacercariae. Exposure of rats to excretory/secretory products of immature F. hepatica conferred a significant degree of resistance which was comparable to the level of resistance induced following oral administration of a low number of metacercariae. No protection against infection was seen in rats injected with excretory/secretory products from mature, bile duct-derived worms. In mice, no obvious mouse strain variation in susceptibility to first infection existed and hypothymic nude mice were as susceptible to infection as intact mice. As determined by protection against death, vaccination with excretory/secretory products derived from immature F. hepatica was without effect in mice. It is concluded that "host protective antigens", at least for rats, were present in the excretory/secretory products of immature F. hepatica larvae.

Animals↗