Search PubMed⌕ Search

Biomedical subjects

G F Mitchell

Publications and source records attributed to G F Mitchell.

At least 235 records · Page 13Linked to original sources
PubMed1978

Protection of mice against plasmodium and babesia infections: attempts to raise host-protective sera.

In an attempt to generate large numbers of mice resistant to Plasmodium berghei and Babesia rodhaini to be used as donors of antibody-secreting cells for hybridoma production, various methods of inducing resistance to repeated challenge with infected blood cells have been explored. Although results of independent experiments varied markedly, prior injection of CBA/M mice with BCG, and prior infection of BALB/c mice with Plasmodium yoelii, were found to be manipulations capable of inducing resistance to P. berghei. A single dose of serum, harvested from resistant mice challenged several times with P. berghei, could transfer resistance against P. berghei to a proportion of naive CBA/H recipients. Although resistance to multiple B. rodhaini challenge could be induced in mice, in no situation was a host protective effect of a single high dose of serum demonstrated in naive recipients.

Animals↗
PubMed1978

Nematospiroides dubius: susceptibility to infection and the development of resistance in hypothymic (nude) BALB/c mice.

BALB/c-nu/nu mice and their intact nu/+ littermates are equally susceptible to infection with third-stage larvae of Nematospiroides dubius. Unlike their heterozygous littermates, however, the nu/nu mice are unable to form ganulomata in the intestinal wall and become only partially resistant to rechallenge. Following two or more infections, nu/nu mice maintain a high burden of adult intestinal worms, whereas worms are lost from immune nu/+ mice. Studies in T cell-injected nu/nu mice suggest that a full complement of T cells is needed to develop maximum resistance against the infective third-stage larvae and to expel adult worms. Measurement of serum immunoglobulin levels indicate that infected nu/+ mice have very high levels of IgG1 whereas the levels of IgG2a are reduced. In infected T cell-injected nu/nu mice, IgG1 levels increase with the number of T cells injected, whereas IgG2a levels are variable but always higher than in infected nu/+ mice.

Animals↗
PubMed1978

Experimental autoimmune orchitis in T-cell-deficient mice.

Experimental autoimmune orchitis (EAO) was induced in inbred strains of mice by injection of mouse testis homogenate (MTH) in Freund's complete adjuvant with pertussis vaccine. Although all mice injected with MTH and adjuvants developed signs of EAO, there were marked strain variations in susceptibility to EAO suggesting that genetic factors may be involved in the response to antigen or to adjuvants. Studies in hypothymic BALB/c. nu/nu mice indicated that a source of T cell was required for induction of EAO. Thus BALB/c. nu/nu mice were not able to develop EAO, despite adequate orchitogenic challenge; reconstitution of nu/nu mice with syngeneic thymocytes completely restored the capacity of such mice to develop orchitis. Transfer of EAO was effected in nu/nu mice with lymphoid cells from appropriately immunized donors but not with immune serum. However, both T cells and antibodies may be necessary in the effector stages of the disease since the capacity of lymphoid cells to transfer EAO was only partially inhibited by anti-Thy-1.2 treatment.

Animals↗
PubMed1978

Maternal alloimmunisation in pregnancy. In vitro studies of T cell-dependent immunity to paternal alloantigens.

A secondary in vitro allograft reaction was used to demonstrate that spleen cells derived from allogeneically mated inbred mice were immunised against paternal alloantigens. In addition to the heightened alloantigen-specific in vitro response of these spleen cells, it was also found that spleen cells froma a wide variety of syngeneically and allogeneically mated mice were nonspecifically more reactive in the in vitro allograft reaction than spleen cells from virgin mice. However, when spleen cells freshly harvested from allogeneically mated mice were tested in a direct 51Cr release assay, lysis of target cells bearing the paternal alloantigens was demonstrable in only one-third of the experiments. It is proposed that T cell immunisation to paternal alloantigens occurs in pregnancy, but that cell-mediated cytotoxicity is inhibited.

Animals↗
PubMed1978

Giardiasis in mice. I. Prolonged infections in certain mouse strains and hypothymic (nude) mice.

The natural history of Giardia muris has been studied in inbred mouse strains and hypothymic (nude) mice derived from a specific pathogen-free facility. Although giardiasis was readily established in several mouse strains, marked variation was observed in the time course of spontaneous elimination of the parasite. During a 10-week study, fecal excretion of Giardia cysts remained relatively constant in C3H/He mice, but decreased at a variable rate in other mouse strains. Resistance to reinfection was greater in strains in which the duration of primary infection was relatively short. Hypothymic (nude) mice derived from a strain showing a relatively rapid elimination of Giardia (BALB/c) maintained a stable infection with high cyst counts. Nude mice reconstituted with lymphoid cells from syngeneic thymus-intact mice showed a progressive reduction in cyst excretion and reconstitution with limited numbers of lymphoid cells from thymus-intact mice previously exposed to Giardia accelerated resolution of infection. In nude mice, giardiasis was associated with a reduction in the villus-crypt ratio of jejunal mucosa, but the degree of change was greater in nude mice reconstituted with lymphoid cells. This Giardia model involving inbred strains and nude mice permits further dissection of the function of thymus-derived cells in intestinal immune responses and induction of changes in small bowel morphology.

Animals↗
PubMed1978

The binding of murine immunoglobulins to staphylococcal protein A.

The binding of murine IgG1, IgG2a, IgG2b, IgG3 protein molecules to Staphylococcal A protein is presented. Differential elution by sodium thiocyanate gradients is described. Proteins of the IgG2 class (either a or b subclass) require between 1.5 and 2.0 M for complete elution, whereas, IgG1 proteins are fully eluted with only 0.5 M NaSCN. These differential elution patterns can be utilized to distinguish between, or prepare proteins of different Ig classes. It is proposed that this quantitative rather than qualitative distinction between Ig subclass binding to Staph A, indicates the existence of multiple binding sites per molecule, with different markers of such sites being present on the heavy chain of the different Ig classes.

Animals↗
PubMed1977

Antigen-induced arthritis in mice. I. Induction of arthritis in various strains of mice.

Antigen-induced arthritis was established in the mouse by immunizaiton with methylated bovine serum albumin (mBSA) in complete Freund's adjuvant with B pertusis vaccine. The knee joint was injected after 21 days with mBSA in saline. The arthritis was chronic, antigen-specific, and T-cell dependent in hypothmic nu/nu mice. C57BL and balb/c mice were susceptible, whereas CBA mice were relatively resistant. Susceptibility was dominant; one gene was loosely linked to the "b" allele of the H-2 complex of C57BL mice.

Animals↗
PubMed1977

Studies on immune responses to larval cestodes in mice. Increased susceptibility of certain mouse strains and hypothymic mice to Taenia taeniaeformis and analysis of passive transfer of resistance with serum.

Various inbred strains of mice vary markedly in their susceptibility to the larvae of the cestode, Taenia taeniaeformis. Males are generally more susceptible than females and the most susceptible common inbred mouse strains are those which are deficient in C5 and/or C4 components of complement. However, no genetic evidence is yet available to implicate loci controlling complement levels in susceptibility/resistance, and multiple genetic factors appear to be operative. Hypothymic, nu/nu ("nude") mice of the relatively resistant mouse strain, BALB/c, are highly susceptible in that cystic larvae in the liver develop in large numbers and more rapidly than in intact BALB/c.nu/+litter-mates. Cyclophosphamide pretreatment also increases the susceptibility of relatively resistant strains of mice in terms of both the number and size of liver cysts. Hypothymic and intact mice can be protected, absolutely, by an injection of serum from infected intact mice, provided the serum is given to recipient mice close to the time of oral egg administration. The protective activity of immune serum is absorbed totally by staphylococcal protein A-Sepharose columns and can be abolished by treatment of recipients with cobra venom factor. Cyst fluid from established larvae facilitates the activity of subhaemolytic amounts of guinea pig complement in a standard direct PFC assay. The data suggest that complement-fixing antibodies are responsible for inhibition of establishing larvae in mice and that one method of protection for established cystic larvae involves the alteration of host complement activity within the cyst.

Age Factors↗
PubMed1977

Studies on immune responses to larval cestodes in mice: a simple mechanism of non-specific immunosuppression in Mesocestoides corti-infected mice.

After intraperitoneal (i.p.) injection of sheep erythrocytes (SRBC) or dinitrophenylated Ficoll (DNP-Ficoll), mice infected with the larval cestode, Mesocestoides corti, contain at least 20x fewer antibody-secreting cells (PFC) in their spleens (or spleens plus lymph nodes) than uninfected mice. By contrast, intravenous injection of antigen leads to normal PFC responses. Results of studies on the fate of labelled syngeneic erythrocytes and foreign proteins suggest that i.p. injected materials are retained in the inflamed peritoneal cavity. Sequestration of antigen, and its subsequent local destruction, presumably accounts for the markedly suppressed systemic immune responses induced by i.p. injected antigens in M. corti-infected mice.

Animals↗
PubMed1977

Studies on immune responses to parasite antigens in mice. V. Different susceptibilities of hypothymic and intact mice to Babesia rodhaini.

Hypothymic BALB/c.nu/nu mice are more resistant than intact BALB/c.nu/+ mice to Babesia rodhaini and a proportion survive a dose of infected blood which is uniformly lethal to nu/+ mice. This proportion of nu/nu survivors is not affected by administration of an anti-Babesial drug, whereas the majority of nu/ + mice develop a long-lasting resistance to infection. The data suggest that T cell dependent activities are involved both in the acceleration of parasitaemia and in the development of drug-assisted resistance.

Animals↗