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At least 19 recordsLinked to original sources
PubMed1978

Studies on the mitogen responses of germfree allogeneic chimeras. II. Maturation of two cell types and partial restoration of responsiveness of the short-term chimeras.

Germfree allogeneic bone marrow chimeras (ABMC) were produced by the i.v. injection of approximately 10(7) bone marrow cells from germfree DBA/2 mice into lethally irradiated germfree C3H mice. In the germfree state, the short-term ABMC showed no histologic signs of graft-vs-host reactions (GVHR), yet splenic lymphocytes were unable to respond to PHA, Con A, or SRBC. Attempts to remove responsiveness by the implantation of a DBA/2 thymus under the host kidney capsule also resulted in failure. However, when the donor thymus was enclosed in a cell-impermeable chamber to eliminate a GVH reaction, responsiveness to Con A was restored. The PHA and SRBC responses were unaffected by this treatment. Daily injections of thymosin caused both an increased Con A response and increased numbers of PFC, although the PHA response was again unaffected. Thus, soluble substances from thymic tissue can be used to overcome partially the histocompatibility barrier present in the ABMC that affects at least two different functional cell populations.

Animals↗
PubMed1975

Rat-mouse radiation chimeras: characterization of an antibody-mediated graft-vs-host reaction.

A modification of the Jerne hemolysis-in-agar technique was used to demonstrate antibody-mediated graft-vs-host (GvH) hemolytic activity in lymphoid tissues of rat-mouse radiation chimeras. Initial foci of hemolytic activity were detected on the 3rd day in spleens of lethally x-irradiated mice infused with rat spleen cells (950 R-RSp chimeras). The peak of GvH foci response occurred near the end of the 1st week when 70% of 950 R-RSp chimera spleens examined contained an average of 18 to 21 foci per spleen. GvH hemolytic activity was also detected in mice reconstituted with rat bone marrow (950 R-RBM chimeras); however, only 40% of these chimeras contained splenic foci (nine foci per spleen) on day 8, the peak day of response. Mesenteric lymph nodes from 950 R-RSp chimeras, but not 950 R-RBM chimeras, also contained GvH hemolytic foci. Specificity experiments demonstrated that the GvH hemolytic reaction could be inhibited with rabbit anti-rat IgM serum and host (C3BF) antigenic cell fragments. Indirect (IgG) hemolytic activity was also observed in spleens of 950 R-RSp chimeras 6 to 10 days after treatment. At least 90% of indirect foci appeared coincident with direct foci. Rat IgM and IgG containing cells beneath hemolytic foci were observed by combining the fluorescent antibody and foci techniques. To determine whether the foci response reflects and in vivo sensitization of donor cells, spleen cell transfer experiments were done. The results indicate that spleen cells from 950 R-RSp chimeras were more effective in acelerating mortality and anemia and induced a higher incidence of Coomb's positive red cells in lethally irradiated isogeneic recipients than spleen cells from 950 R-RBM chimeras; spleen cells from either chimera were more effective in accelerating GvH indices than spleen and marrow cells from normal rats.

Animals↗
PubMed1978

[Status of T- and B-lymphocytes in long living CBA--F1 (CBA X C57BL/6) chimeras].

Semiallogeneic chimeras were produced by injecting 3 X 10(7) spleen cells of mice CBA (H--2k, Mlsd) to lethally irradiated mice (CBA X C57BL/6)F1. Two days later recipients were given cyclophosphamide (CP), 2 mg per mouse, to prevent death of graft versus host reaction (GVHR). For 1.5--2 months after the creation of chimerism in 23 of 26 mice under study all cells producing antibodies to SRBC were represented by donor cells of H-2 phenotype; 3 mice were partial chimeras. Spontaneous blast transformation in the cultures of chimera spleen did not exceed the control level, and in the mixed lymphocyte culture chimera cells failed to proliferate on addition of irradiated lymphocytes (CBA X C57BL/6) F1. At the same time chimera gave intensive blast transformation to the irradiated lymphocytes of the third line of mice DBA/2 (H--2d, Mlsa). Among the chimera spleen cells no killers capable of destroying target cells of donor or recipient origin were revealed. Similar results were obtained in vivo: chimera cells gave no positive local GVHR after administration to mice (CBA X C57BL/6) F1. Prolonged chimerism was accompanied by a reactivity of donor T-lymphocytes to the recipient transplantation antigens. A blocking factor was revealed in the blood serum of chimeras. The substitution of donor lymphocytes for the recipient cells begins after 3 to 5 months. At the same period donor T-cell population reconstitutes partially the responsiveness to the recipient antigens and the blocking factor disappears from chimeras blood.

Animals↗
PubMed1977

Immune competence of splenic lymphocytes following graft-vs-host disease in mouse allogeneic radiation chimeras.

The abnormal immune response of long-term mouse allogeneic chimeras is reflected by qualitative deficiencies in either T or B lymphocytes. The present study was undertaken to determine if a relationship existed between the severity of graft-vs-host disease (GVHD) that these animals had experienced and a functional defect in either the T or B cell population. The in vitro PFC response of chimera spleen cells to sheep red blood cells (SRBC) was evaluated in the presence of normal T or B lymphocytes 4 to 8 months after marrow transplantation and well beyond the GVHD period. In an analysis of several different allogeneic radiation chimeras, our results showed no relationship between the severity of GVHD experienced and the immunologic capacity of either T or B cells. Thus, different chimera combinations showing similar degrees of GVHD were functionally deficient in one or the other of these two cells types or both with no apparent predilection for abnormality in either population. In examining the quantitative in vitro PFC response to sheep RBC by spleen cells from individual chimeras, we found that the number of PFC formed was related to the severity of GVHD experienced by that animal. A general relationship between severity of GVHD and PFC capacity may also exist between chimeras of different genetic combinations. However, this relationship is not precise since gross exceptions occur. Our results, although documenting further the qualitative abnormalities in T and/or B lymphocytes of radiation chimeras, do not reveal the factor or mechanisms by which these cells are made unresponsive. It is suggested that the tolerance-inducing mechanism of these animals, whether it be humoral blocking factors or suppressor cells, is in some way interfering with the collaboration of T and B cells for antibody production.

Animals↗
PubMed1977

Sex determination in germ line chimeras of Drosophila melanogaster.

Of 55 flies developing from blastoderms which had received male or female pole cell transplants, 15 (7 females and 8 males) wer shown by progeny testing to be germ line chimeras. Since donor and host pole cells were genetically marked with contrasting X- or Y-linked alleles, the progeny testing scheme enabled the genotypic sex of the donor component undergoing gametogenesis to be identified as either the same as ('homosexual' chimeras) or opposite ('heterosexual' chimeras) that of the host. All seven of the female chimeras were identified as 'homosexual' chimeras carrying only chromosomally female XYX donor and XX host germ cells. Similarly, all eight males were shown to be 'homosexual' chimeras with chromosomally male XY donor and XY host germ cells. The chromosomal sex of the donor component undergoing gametogenesis was in every case the same as the phenotypic sex of the host. Since there is an equal probability of constructing either a 'homosexual' or a 'heterosexual' chimera during pole cell transplantation, the ability of pole cells to differentiate functional gametes in hosts of the opposite sex was tested 50% of the time even if sex reversal of these donor pole cells could not be demonstrated. Thus the absence of 'heterosexual' chimerism strongly supports the interpretation that the phenotypic sex of a germ cell in Drosophila is determined entirely by its own chromosome constitution, not by that of the gonadal mesoderm.

Animals↗
PubMed1979

Nature of T-cell macrophage interaction in helper-cell induction in vitro. II. Two stages of T-helper-cell differentiation analyzed in irradiation and allophenic chimeras.

The genetic restriction in the T-cell-macrophage-like cell interaction in helper cell induction was investigated with allophenic and irradiation chimeras of various types. Using T cells from P leads to F1 chimeras, there was a restriction of cooperation with the parental haplotype accessory cells, unless the chimeric mice were repopulated with macrophages of the opposite haplotype before priming. T cells from primed or unprimed F1 leads to P chimeras only cooperated with recipient type accessory cells. These observations led to the hypothesis that there are two stages in the genesis of immunocompetence of T helper cells, one dependent on the thymus, and the other on peripheral macrophage-like cells. Purified T cells from P1 + P2 leads to F1 irradiation chimeras behaved in an unexpected manner in the unprimed state, preferring to cooperate with their own haplotype macrophages. This self preference was lost after antigen priming in vivo and was not noted in allophenic chimeras. This loss of self preference was restricted to the haplotypes represented in the chimeras, and did not extend to third party haplotypes. While these in vitro induced helper cells from chimeric mice show clear genetic restrictions at the T-cell macrophage-like cell interaction, there was no evidence for a matching T-B genetic restriction.

Animals↗
PubMed1979

Lymphoid function in F1 leads to parent chimeras: lack of evidence for adaptive differentiation of B cells or antigen-presenting cells.

Information was sought on whether B cells undergo abnormal differentiation in F1 leads to parent chimeras (irradiated parental-strain mice reconstituted with F1-hybrid bone marrow cells). As assessed by collaborative responses to sheep erythrocytes in vivo, three different types of T cells restricted to interaction with strain a H-2 determinants were shown to collaborate as effectively with heterologous F1 leads to b chimera B cells as with homologous F1 leads to a chimera B cells. This applied to both primed and unprimed B cells, to IgM- and IgG-antibody formation and to production of Ig allotype. Thus, unlike T cells, B cells from F1 leads to parent chimeras behaved indistinguishably from normal F1 B cells. F1 leads to parent chimeras were also examined for their capacity to present antigen to normal F1 T cells in vivo. The results suggested that the antigen-presenting cells in these chimeras were no different than in normal F1 mice. Collectively these data imply that, at least in the situation studied, raising F1 stem cells in a parental-strain environment has a marked effect on T-cell specificity but does not discernably influence the differentiation of B cells or macrophage-like cells.

Adaptation, Physiological↗
PubMed1975

Failure to detect anti-group-specific murine leukemia virus activity in tetraparental AKR-CBA chimeras.

Tetraparental AKR-CBA/H-T6 chimeras were primarily derived and investigated to determine whether factors associated with the tumor resistance of the CBA/H-T6 could overcome the innate lymphoma susceptibility of the AKR. Evidence has since shown that, on comparison with the AKR, lymphomas were not only delayed but were also less common in a group of 18 early embryo aggregation derived AKR-CBA/H-T6 tetraparental chimeras. Evidence here has shown other clear differences between the AKR and AKR-CBA/H-T6 chimeras. Whereas murine group-specific murine leukemia viral antigens were detected in the sera in both situations, immunoabsorption studies showed that, in the AKR, the antigens exist complexed to the corresponding antibodies. The situation in the chimeras was in complete contrast, since here antigens exist as a "free" form. This in turn has led us to suggest that the advantage in respect to tumor immunity in the AKR-CBA/H-T6 chimeras is due to the tolerance to oncogenic virus being maintained. In this situation and in contrast to the AKR, in the absence of "masking" antibody-viral antigenic complexes, "normal" tumor immunity can be effected. It has to be assumed that tolerance to the oncogenic Gross virus in the AKR-CBA/H-T6 chimeras reflects the influence of the CBA component. How this has possibly been achieved is discussed.

AKR murine leukemia virus↗
PubMed1977

Synthetic multifunctional proteins: isolation of covalently linked tryptophan synthetase alpha-subunit-lac-repressor-beta-galactosidase chimeras.

Several E. coli mutants were isolated which produce triple chimeras between one of the trp enzymes lac, repressor and beta-galactosidase. The mutants were isolated as TonB- Lac+ derivatives of a phenotypically Lac- TrpR- strain carrying a lac I+ -Z+ fusion on a phi80dlac phage. The phage is integrated into the chromosome in such a way that the lac and the trp genes are transcribed in the same direction. Of a total of 58 candidates 2 TrpA- and 3 Trp- strains produce triple chimeras. The chimeras from the two TrpA- strians were further examined. They consist of tryptophan synthetase alpha-subunit, lac repressor and beta-galactosidase. In crude extracts of these strains the tryptophan synthetase alpha-subunit part can be identified by its ability to aggregate with the beta-subunit since some of the beta-subunit activity can be precipitated with antiserum against beta-galactosidase. Furthermore beta-galactosidase precipitates with antiserum against tryptophan synthetase alpha-subunit. The lac repressor part is able to bind IPTG, but not lac operator DNA in vitro. The beta-galactosidase part is as unaffected as in the original lac repressor-beta-galactosidase chimera. The molecular weights of both chimeras are 175,000 when determined by SDS gel electrophoresis. The chimeras are partially degraded giving rise to fragments of distinct molecular weights.

Bacterial Proteins↗
PubMed1979

Primary anti-viral cytotoxic T-cell responses in semiallogeneic chimeras are not absolutely restricted to host H-2 type.

Chimeras produced by reconstitution of 950 rads irradiated type A or type B host mice with (AXB)F1 fetal liver stem cells were examined in primary (in vivo) and secondary (in vitro) Tc-cell responses to ectromelia virus infection. Of 33 individual chimeras which gave primary responses, 26 produced significant specific lysis of infected targets of both A and B type, though host type targets were invariably lysed more efficiently (host bias). The other 7 chimeras gave lysis of infected host type targets only (absolute restriction). 12 individual chimeras were used in secondary responses. Nine showed host bias, and three showed absolute restriction. Whether an individual chimera showed host bias or absolute restriction seemed to be unrelated to whether the response was primary or secondary, to the time after reconstitution (ranging from 4 to 22 wk), to strain of mouse, or to the batch of fetal liver stem cells used.

Animals↗
PubMed1979

Patterns of virus-immune T-cell responsiveness. Comparison of (H-2k X H-2b) leads to H-2b radiation chimeras and negatively selected H-2b lymphocytes.

Negatively selected H-2K(b)D(b) TDL can be induced to respond strongly to vaccinia virus presented in the context of both H-2K(k) and H-2D(b) when stimulated in irradiated H-2K(k)D(b) recipients. Addition of excess (H- 2K(k)D(b) x H-2K(b)D(b))F1 TDL, which are low responders to H-2D(b)-vaccinia virus, does not obviously suppress the reactivity pattern of the H-2K(b)D(b) T cells. However, lymphocytes from chimeras made by reconstituting H- 2K(b)D(b) mice with (H-2K(k)D(k) x H-2K(b)D(b))F(l) bone marrow cells make little, if any, cytotoxic T-cell response to vaccinia virus when sensitized in H-2K(k)D(b) recipients. We have thus documented one instance where the responder phenotype of T ceils from an F(l) {arrow} parent chimera is not equivalent to that associated with the H-2 type of the parental thymus. Lymphocytes from both the chimera and the H-2K(b)D(b) parent (after negative selection) are tolerant to the H-2K(k) and I-A(k) alloantigens encountered in the recipient, but the chimera T cells are also defective in their response to a neoantigen (vaccinia virus) presented in the context of H-2K(k) which the parental T cells invariably recognize. It is thus possible that at least part of the phenomenology associated with the F(l) {arrow} parent radiation chimeras reflects deletion of repertoire in the context of H-2 antigens present during thymocyte ontogeny on other than radiation-resistant thymic epithelium.

Animals↗
PubMed1975

Specific inhibition of the graft-versus-host reaction in fetal or neonatal liver chimeras.

The fetal liver chimera system was used as a model to study the nature of transplantation tolerance in radiation chimeras. A permanent state of tolerance was induced in (C3H/eb times C57BL/6)F1 irradiated mice after reconstitution with parental C57BL/6 fetal or neonatal liver cells. It was found that although enough host hemopoietic cells were present in such chimeras to provide antigenic stimulation, subsequent inoculation of these chimeras with C57BL/6 immunocompetent cells syngeneic to liver donor cells specifically abolished their response against the host. In addition, cells obtained from liver chimeras after their challenge with C57BL cells were unable to produce a graft-versus-host response upon transfer to (C3H/eb times C57BL/6)F1 newborn mice. Transfer of serum of these mice could not prevent immune reactivity of syngeneic C57BL/6 cells neither in the graft-versus-host nor in the mixed lymphocyte culture assays. These observations are compatible with the hypothesis that suppressor cells may differentiate within the fetal liver, which specifically inhibits the immune reactivity of syngeneic cells, and thus leads to the establishment of tolerance.

Animals↗
PubMed1977

Allogeneic bone marrow transplantation in conventional mice: I. Effect of antibiotic therapy on long term survival of allogeneic chimeras.

In the present communication the beneficial effect of long term antimicrobial treatment with poorly absorbable antiboitics on the survival of allogeneic bone marrow chimeras was investigated. The combination of C57Bl mice as bone marrow donors and CBA/CA mice as irradiated recipients (800 rad) was used because of their strong histoincompatibility on the H-2 loci. All allografted recipients received 10 X 10(6) bone marrow cells. The majority of the recipients, which were rendered gnotobiotic by an antimicrobial treatment, achieved stable long term chimerism. In contrast, the conventional chimeras died from secondary disease within 9 weeks after transplantation. As early as 14 days after allogeneic bone marrow grafting the gnotobiotic recipients tolerated the reassociation with a conventional microflora without a change in the rate of mortality. Bone marrow cells (8 X 10(6) i.v.) and spleen cells (2 X 10(6) i.v.) collected from allogeneic chimeras failed to induce graft-versus-host-reaction (GVH) in a second lethally irradiated host. The data indicate, that the high rate of mortality in murine allogeneic bone marrow chimeras results from delayed GVH-reaction and systemic infection. The marrow graft, once established seems to exert tolerance against the allogeneic host. The pathogenesis of the systemic infection has not yet been worked out. It is assumed that it originates from bacteremia, induced by radiation dependent lesions of the epithelial integrity and defected lymphatic tissue in the gut.

Animals↗
PubMed1977

[Organ tolerance and incomplete bone marrow chimera in dogs].

Cyclophosphamide-induced chimeras develop organ tolerance as do radiation chimeras, as long as hemopoietic cells of donor origin are detectable, independent of the degree of chimerism (n = 7). 4 of 7 dogs with reversion of chimerism rejected their kidney grafts within 11 to 29 days. Three of them, however, retained their kidney grafts permanently indicating that a transient chimerism of a few months duration may be sufficient for induction of tolerance to marrow donor organs in Cy-chimeras. The results suggest that the reversion of chimerism in Cy-chimeras may be due to different mechanisms either immunological rejection or a non-immunological substitution of the grafted marrow by the host's own hemopoiesis.

Animals↗
PubMed1979

Adaptive differentiation of murine lymphocytes. II. The thymic microenvironment does not restrict the cooperative partner cell preference of helper T cells differentiating in F1 leads to F1 thymic chimeras.

The cooperating preference of helper T cells originating from F1 bone marrow, but differentiating in adult thymectomized, lethally irradiated F1 recipients reconstituted with either f1 or homozygous parental thymus grafts was investigated. Cooperating preference was assayed by determining the levels of helper activity provided by antigen-primed T cells derived from such thymic chimeras for hapten-primed B lymphocytes obtained from conventional F1 or parental donors in adoptive secondary antibody responses in vivo. The results of these analyses revealed a tendency of helper T cells derived from parental thymic chimeras to provide better help for B cells of the same parental type corresponding to the origin of the thymus graft than for the opposite parent. Such preference was, however, only marginal and rarely were differences in levels of helper activity provided to the respective parental types statistically significant. Moreover, this marginal preference, when observed, pertained only to responses of the IgG class; no concordant preference in providing helper activity for IgE antibody responses was observed even with the same populations of thymic chimera helper T cells. Finally, in no instance was there any evidence of restriction in the classical sense of presence versus absence of help as we have routinely observed in all of our previous studies concerning genetic restrictions of T-B-cell cooperative interactions. Although the basis for differences in the studies reported here when compared to observations made in cytotoxic T-lymphocyte systems is unclear, and could reflect genuine mechanistic requirements concerning what directs H-2 restrictions in helper T cells and cytotoxic T lymphocytes, respectively, it is also possible that we are placing too much faith in our interpretations of data obtained in bone marrow chimera systems than is perhaps justified by the potentially great fragility of such systems.

Animals↗
PubMed1979

T-helper function of parent leads to F1 chimeras. Presence of a separate T-cell subgroup able to stimulate allogeneic B cells but not syngeneic B cells.

Parent leads to F1 chimeras were prepared by reconstituting sublethally irradiated H-2 heterozygous mice with marrow cells from one parental strain. Purified parental strain T cells prepared from unprimed chimeras were exposed to sheep erythrocytes in heavily irradiated mice of each of the two parental strains and recovered from thoracic duct lymph of the recipients at either day 1 or day 5 posttransfer. The lymphoborne cells were then tested for their capacity to collaborate in vivo with B cells of the two parental strains. From this approach it was concluded that parent leads to F1 chimera T cells contain two discrete subgroups of T-helper cells, one specific for self H-2 determinants and the other restricted to H-2 determinants of the opposite parental strain. The restrictions mapped to the K-end of the H-2 complex.

Animals↗
PubMed1979

Natural, genetically determined resistance toward influenza virus in hemopoietic mouse chimeras. Role of mononuclear phagocytes.

Radiation chimeras produced by crosswise transfers of bone-marrow cell among histocompatible mice susceptible, or genetically resistant, to lethal challenge by a number of myxoviruses were used to test whether macrophage resistance (as assessed in vitro) and resistance of the animal (as measured in vivo), both previously shown to be brought about by the gene Mx, were causally related. 49 chimeras were tested individually, both of resistance of their macrophages to in vitro challenge with M-TUR (a strain of avian influenza virus A/Turkey/England/63 adapted to grow in cultured mouse peritoneal macrophages), and for resistance of the animal in vivo upon challenge with pneumotropic, neurotropic, or hepatotropic influenza viruses. Cultivated Kupffer cells and peritoneal macrophages harvested from chimeric mice expressed the resistance phenotype of the bone-marrow donor irrespective of the host environment in which they had differentiated. However, susceptibility or resistance in vivo was according to the genotype of the host. Thus, inborn resistance of radiation chimeras was found to be independent of Mx-gene expression in cells of the hemopoietic system.

Animals↗
PubMed1975

Allogeneic unresponsiveness to orthotopic cardiac transplants in DL-A-identical radiation chimeras.

Nine Cooperstown beagles of known DL-A genotypes were exposed to supralethal total-body irradiation and received bone-marrow allografts from DL-A-identical donors. Four to 5 months later, the resulting chimeras received orthotopic cardiac allografts from their corresponding donors of marrow. Six chimeras died of operative complications in the immediate postoperative period. The other 3 chimeras survived from 173 to 547 days; 1 dog died at 173 days as a result of right-sided heart failure, secondary to stenosis at the site of the pulmonary artery anastomosis. The other two recipients continue to be active and healthy at 545 and 547 days. The results indicate that dogs can be rendered specifically tolerant to orthotopic cardiac allografts by supralethal total-body irradiation and the transplantation of marrow obtained from the prospective allograft donor.

Animals↗