Biomedical subjects

F Loor

Publications and source records attributed to F Loor.

At least 55 records · Page 3Linked to original sources

PubMed1991

A quick procedure for identifying doubly homozygous immunodeficient scid beige mice.

This article describes a rapid and reliable procedure for identifying mice which are doubly homozygous at the scid and beige (bg) loci starting from CB17 scid (no T and B cells) and B6 bg mice (no NK activity). The [scid, bg] mice are directly identified in the F2 progeny by monitoring (1) the hypogammaglobulinemia for the scid gene and (2) the prolonged bleeding associated with the bg gene. Like CB17 scid mice, the [scid, bg] mice show a high susceptibility to infections and die early in life unless they are protected against potential infections. This is achieved by a graft of splenocytes plus bone marrow cells from (B6 bg x CB17 scid) F1 mice. These [scid, bg] mice combine the bg and scid immunodeficiencies and should be better recipients for xenografts than classical scid mice.

Animals↗

PubMed1991

Restoration of daunomycin retention in multidrug-resistant P388 cells by submicromolar concentrations of SDZ PSC 833, a nonimmunosuppressive cyclosporin derivative.

Overexpression of P-glycoprotein may cause increased efflux of a variety of anticancer drugs (ACD) leading to multidrug resistance (MDR) of tumor cells. Two sublines of murine monocytic leukemia P388 cells were used, one parental (Par-P388) and one multidrug resistant (MDR-P388). In cell growth inhibition assays in vitro, the Par-P388 cells showed a normal sensitivity to daunomycin (DAU) while the MDR-P388 cells were 200-fold resistant. In cellular fluorescence assays, DAU retention in MDR-P388 cells reached only 5% of the level achieved in Par-P388 cells. This cell line pair was used to compare the nonimmunosuppressive cyclosporin analog PSC 833 with several resistance-modifying agents (RMAs) for their in vitro chemosensitizing activity and for their restoration of DAU retention. PSC 833 sensitized the MDR-P388 cells 60- and 140-fold when used at 0.1 and 0.3 micrograms/ml (0.08 and 0.25 microM), respectively, a complete restoration of sensitivity being obtained at 1.0 micrograms/ml PSC 833. Similarly as little as 0.1 micrograms/ml (0.08 microM) PSC 833 was sufficient to restore intracellular DAU retention to 60% of the level found in Par-P388 cells, a 3-fold higher concentration restoring virtually the whole DAU retention. For both these activities, PSC 833 was at least one order of magnitude more active than CsA, which was itself an order of magnitude stronger than verapamil, another RMA already used in clinic. Since PSC 833 had no effect on the PAR-P388 cells, neither on chemosensitization nor on drug retention, it is assumed that it acts on the P-glycoprotein, which is highly expressed on the membrane of the MDR-P388 cells, by inhibiting the function of the P-glycoprotein pump and thus restoring a normal ACD-sensitivity of the MDR-P388 cells.

Amiodarone↗

PubMed1991

FK-506 (fujimycin) reverses the multidrug resistance of tumor cells in vitro.

Cyclosporin A (CsA) and FK-506 have similar immunosuppressive activity profiles and cyclophilin-like intracellular targets. Since CsA can reverse the multidrug resistance of tumor cells showing P-glycoprotein-mediated drug efflux, the possible resistance-modulating activity of FK-506 was evaluated in vitro with multidrug-resistant P388 cells and their sensitive parental controls. Higher concentrations of FK-506 than CsA were needed to achieve a similar degree of chemosensitization, suggesting that FK-506 might interact less efficiently than CsA with the P-glycoprotein expressed in multidrug-resistant tumor cells. However, FK-506 was active on a broader range of concentrations than CsA, particularly because of direct cytostatic effects of CsA which appeared at concentrations only slightly higher than those required to show a significant resistance-modulating activity.

Amiodarone↗

PubMed1991

Different nature of the proliferation defects of GLD, LPR and MEV C57BL/6 mouse lymphoid cells.

The three non-allelic gld, lpr and mev mutations in the mouse all lead to profound immunodeficiency besides a splenomegaly and a generalized autoimmunity. Spleen cells from young B6 gld, B6 lpr and B6 mev mice all display a decreased proliferative response to the T-cell mitogen concanavalin A (ConA), but the nature of the deficiency seems very different. No restoration of proliferation could be obtained by adding exogenous recombinant rIL2 to ConA-treated mev spleen cells, this lack of IL2-responsiveness suggesting a lack of (functional) IL2-receptors. In young mice of both gld and lpr strains, a B6 wild-type level of proliferation could be reached by rIl2 addition to ConA-treated spleen cells, this normal responsiveness to exogenous IL2 suggesting a normal expression of IL2-receptors. The endogenous IL2 production by ConA-treated spleen cells decreased very much with ageing in both B6 gld and B6 lpr mice. Yet, IL2 production in young mice revealed an earlier deficiency of the B6 lpr mice: the young B6 gld IL2 levels reached about 60% of age-matched B6 wild cell levels, but the B6 lpr levels reached 14% only. Finally the addition of exogenous rIL2 to ConA-pretreated cells from old B6 gld and B6 lpr mice, while enhancing the proliferative responses, could not restore the B6 wild-type levels. This suggests that, with ageing, the expression of functional IL2-receptors may become as abnormal in these gld and lpr mutants as it is from birth in the mev mutant mice.

Age Factors↗

PubMed1991

Immunoglobulin isotypes of C57BL/6 nu/nu, lpr/lpr mice. Lack of direct intrinsic effect of the lpr gene on B cell hyperactivity.

The absolute concentrations of mouse immunoglobulin (Ig) heavy chain isotypes were determined by specific ELISAs in the serum of C57BL/6 (B6) mice doubly homozygous at the nude (nu) and the lymphoproliferation (lpr) locus (B6 nu, lpr mice), and compared with normal B6 nu mice. The distribution and the absolute concentrations of all Ig isotypes were found to be very similar in B6 nu, lpr and B6 nu mice, for both sexes and with similar increases in titers with ageing. Thus, the major part of the severe autoimmunity and hyperglobulinemia characteristic of the lpr syndrome of euthymic B6 lpr mice, including their elevated titers of thymus-independent IgM and IgG3 isotypes, is abrogated by the nude mutation, an effect of which is the lack of thymus differentiation. Though a postulated intrinsic activity of the lpr gene directly on B cell hyperactivity cannot be discarded, its expression would then require the presence of either the thymus or of T cells or of other cells or factors whose expression is also abrogated by the homozygosity at the nude locus.

Aging↗

PubMed1991

Adoptive transfer of viable motheaten pathology in sublethally irradiated beige recipient mice.

B6 viable motheaten (mev) mice are short-living autoimmune and immunodeficient mice. Most of the mev pathology is transferable into the B6 beige (bg) irradiated mouse by injection of mev haematopoietic cells. Indeed there is a rapid establishment of lung damage, thymus aplasia, inflammation and necrosis of peripheral joints, an increase of serological IgM concentrations and autoantibody levels as well as a rapid death. This mev-type pathology can be again obtained by transferring haematopoietic cells of these [mev----bg] chimeras into other irradiated bg mice, although the appearance of these serological and phenotypical symptoms seems to be more and more delayed when doing cascade transfers.

Animals↗

PubMed1991

Haematopoietic cell transfers between C57BL/6 mice differing at the lpr or gld locus.

The generalized lymphoproliferative disease (gld) and lymphoproliferation (lpr) mutations induce the development of strikingly similar autoimmune and lymphoproliferative syndromes in C57BL/6 mice (B6). These syndromes are characterized by hyperglobulinaemia, high levels of circulating autoantibodies and significant splenomegaly and lymphadenopathy resulting principally from the accumulation of a double negative CD4/CD8 T-cell population. These similarities led to the suggestion that the gld and lpr mutations affect two different steps of a common metabolic pathway controlling the differentiation of the T cells. By transferring haematopoietic cells into sublethally irradiated recipients we provide evidence for the different aetiology of the gld- and lpr-induced syndromes. The [gld----gld] chimaeras developed a gld-induced syndrome, like the [lpr----lpr] chimaeras developed a lpr-induced syndrome. However, in contrast to the severe lymphoid aplasia observed in the [lpr----wild] chimaeras, the [gld----wild] chimaeras showed an attenuated form of the gld-induced syndrome. The [lpr----gld] chimaeras developed a lymphoid aplasia (as in the [lpr----wild] chimaeras). This result shows that the gld environment cannot substitute for the lpr environment and allow for the emergence of an lpr-induced pathology.

Animals↗

PubMed1991

Reciprocal haematopoietic cell transfers between C57BL/6 mice differing at the lpr locus.

Reciprocal transfers of spleen and bone marrow cell suspensions have been performed between mice of the C57BL/6 (B6) genetic background, differing at the lymphoproliferation (lpr) locus. These immune system chimaeras were followed for almost one year after sublethal irradiation and cell reconstitution. In addition to the survival of the chimaeras, the major lymphoid organs (bone marrow, spleen, thymus and lymph nodes) were examined for cell numbers, percentages of membrane immunoglobulin-positive cells and responses to mitogenic stimulations with concanavalin and lipopolysaccharide. The [lpr----lpr] chimaeras were similar to untreated lpr mice. The [wild----lpr] did not develop the lpr-induced syndrome and remained similar to [wild----wild] chimaeras. Therefore, B6 wild haematopoietic stem cells could rescue sublethally irradiated B6 lpr mice from the lpr-induced autoimmune pathology. The radioresistant lpr environment alone was not sufficient to induce the lpr syndrome. It may however be required for its development since [lpr----wild] chimaeras displayed a profound aplasia of their lymphoid organs, together with a normal cellularity of their bone marrow. In contrast to chimaeras constructed with MRL mice, the [lpr----wild] B6 chimaeras did not die following the lpr haematopoietic stem cell transfer. Therefore, the lymphoid aplasia of [lpr----wild] radiation chimaeras does not result from an lpr graft-versus-host-like syndrome. More likely is that a normal, non-lpr, haematopoietic environment may not allow the differentiation of the lpr haematopoietic stem cells into the lymphoid lineages.

Animals↗

PubMed1990

Common and individual features of the humoral immunity dysregulation of mice homozygous at the viable motheaten (mev) mutation.

The "viable motheaten" (mev) mutation in the C57BL/6 (B6) mouse causes in mev-homozygous B6 mice a rapidly progressing and fatal autoimmune syndrome, combined with a generalized immunodeficiency. Serological analyses of a large number of mev/mev individual mice revealed profound abnormalities of the levels of various spontaneously occurring, natural antibodies and of the levels and distribution of the different classes of immunoglobulins, some common to all mev/mev mice and some specific to individual mice. Although very high serum IgM levels (70X the normal B6 mouse serum level) and high anti-ssDNA titers are common features, the increases in the other immunoglobulin isotypes are not so marked (4.7X for IgG3, 2.7X for IgA, 1.6X for IgG1 and IgG2b, and even 0.6X for IgG2a), and the occurrence of other natural antibody specificities shows more individual variability.

Animals↗

PubMed1990

Impaired antibody response of C57BL/6 beige mutant mice to a thymus-independent type 2 antigen.

The murine equivalent of the human Chediak-Higashi Syndrome is the beige (bg) mutant in the C57BL/6 (B6) background. Besides the well-known lack of natural killer (NK) activity in bg-homozygous mice, functional abnormalities of T cells, macrophages and various granulocytes have been reported. With the exception of one study indicating a decreased in vitro response to lipopolysaccharide, there is no report concerning the B cell compartment of the beige mutant. The in vivo anti-trinitrophenyl antibody response to a TI-2 antigen (TNP-Ficoll) was found here to be significantly lower in B6 beige than in B6 wild mice, although both strains responded similarly to an analogous TD antigen (TNP-ovalbumin). Since the marginal zone macrophages of the spleen were previously shown to be essential for the initiation of antibody responses to TI-2 antigens, they might be another target of the beige mutation.

Animals↗

PubMed1990

Partial expression of the viable motheaten (mev) mutation in the heterozygous state: abnormal levels of serum immunoglobulins and natural anti-ssDNA antibodies.

The 'viable motheaten' (mev) mutation in the C57BL/6 (B6) mouse causes a rapidly progressive and fatal autoimmune syndrome in mev-homozygous B6 mice, combined with generalized immunodeficiency, whereas the mev-heterozygous B6 mice look phenotypically normal. However, serological analyses of the levels of some spontaneously occurring, natural antibodies and of the levels and distribution of the different classes of immunoglobulins revealed mild but evident dysregulation of the natural humoral immunity of +/mev individuals.

Animals↗

PubMed1990

Reciprocal lymphoid cell homing studies using wild and LPR (lymphoproliferation) mutant C57BL mice.

The injection of lymphoid cells from adult lpr mice into normal and athymic congenic mice does not transfer the lpr (lymphoproliferation) syndrome. We studied whether this phenomenon could be due to abnormal homing. The lymphoid cells from lpr donors do not show a marked deficiency of migration to lymphoid organs in comparison with cells from Wild donors and a T-cell lymphoma BL/VL3. The lymphoid organs of lpr recipients do not show an intrinsic abnormality as homing sites for lymphoid cells. The data reveal some minor migration preferences: the lpr cells migrate better than Wild cells into lpr lymph nodes (including athymic lpr hosts), whereas Wild cells migrate slightly better than lpr cells into Wild lymph nodes. In spite of such minor preferences, Wild cells can efficiently migrate into lpr lymphoid organs, as well as lpr cells into Wild lymphoid organs. Thus, the lack of transfer of lymphadenopathy in Wild recipients cannot be attributed to an alteration of lpr cell homing.

Animals↗

PubMed1990

Serum concentrations of IgM, IgG1, IgG2b, IgG3 and IgA in C57BL/6 mice and their congenics at the nu(nude)locus.

The absolute concentrations of IgM, IgG1, IgG2b, IgG3 and IgA were determined in mice of C57BL/6 background, from weaning to one year of age, by quantitative isotype-specific, indirect double sandwich ELISAs. The comparison of 10-40 weeks-old athymic nude C57BL/6 females with age matched females of the wild strain showed a general decrease of the whole serum Ig levels in the athymic mice, which was however contributed quite differently by the different Ig isotypes: a significant decrease (about 3.5 fold) was found for IgG2b only (0.34 mg/ml), whereas 1.5 fold more IgM (0.28 mg/ml) and about 2 fold more IgG3 (0.27 mg/ml) were detected, the IgG1 (0.19 mg/ml) and IgA (0.07 mg/ml) levels remaining within the normal range ! Limited data for IgG2a suggest that that this isotype may also be decreased in nude mice (0.36 mg/ml) in comparison with normal B6 + mice (0.54 mg/ml). Thus, although homozygosity at the nu locus results in a lack of effector T cells, our data show, at the humoral level, a limited degree of thymus dependence of an Ig isotype. It is intriguing that, although thymus dependence of several Ig isotypes looked evident ten years ago in early studies on nude mice, more recent data are very variable and controversial in this respect.

Animals↗

PubMed1990

Adoptive transfer of viable motheaten (mev) humoral autoimmunity: IgM to IgG switch of the hyperglobulinaemia in nude, beige recipient mice.

Homozygous C57BL/6 nude, beige mice (B6 nu,bg) were used as recipients for the transfer of lymphoid cells from autoimmune homozygous B6 'viable motheaten' mice (B6 mev) and from either normal B6 mice (B6 wild) or B6 bg mice as controls. Surprisingly, the mev cell grafts prolonged survival of these short-living doubly immunodeficient recipients. Although the [mev----nu,bg] chimeras did not develop the mev external necrosis phenotype, they showed a hyperglobulinaemia and a significant increase of their anti-single-stranded DNA (ssDNA) antibody titres, compared to control chimeras ([bg----nu,bg] and [wild----nu,bg]). However, this hyperglobulinaemia was quite different from the mev-type hyperglobulinaemia, with poor contribution of the IgM isotype. Moreover, the anti-ssDNA antibodies were more distributed among the various Ig classes than the anti-ssDNA antibodies of the mev homozygous mice. Though the adoptive transfer of some mev-type humoral autoimmunity symptoms were achieved in this chimera model, the recipient mice did not suffer from the several other features of the mev syndrom, such as the severe pathology and the extremely high IgM serological levels.

Animals↗

PubMed1990

Adoptive transfer of viable motheaten humoral autoimmunity in cyclophosphamide-immunodepressed beige recipient mice.

Cyclophosphamide-pretreated homozygous C57BL/6 beige mice (B6 bg) were used as recipients for the transfer of lymphoid cells either of short-living autoimmune homozygous B6 'viable motheaten' mice (B6 mev) or of normal B6 mice (B6+) or B6 bg mice as controls. The grafts had no incidence on the survival of the recipients, whatever protocol used. The [mev----bg] chimeras did not develop the mev external phenotype, but there was a transfer of humoral autoimmunity. Compared to control Compared to control chimeras ([bg----bg] and [+----bg]), recipients of mev cells always showed an increase in anti-single-stranded DNA (ssDNA) antibody titres, reaching 2/3 of the mev ones 40 weeks after the cell transfers. Moreover, the anti-ssDNA were mainly of IgM class, correlating with the higher total IgM level found in [mev----bg] chimeras, thus reflecting the serological phenotype of the mev homozygous mice. Though the adoptive transfer of some mev-type humoral autoimmunity symptoms was clearly achieved in this chimera model, the recipient mice did not suffer from the several other features of the mev syndrome, such as the hyperglobulinemia and the severe pathology. This indicates that microenvironmental influences act in concert with B cells to produce pathology in mev mice.

Animals↗

PubMed1989

An indirect asymmetrical sandwich ELISA using anti-allotype antibodies for the specific and quantitative measurement of mouse IgG2a of Igh-1b allotype.

We recently described an indirect double sandwich ELISA (Klein-Schneegans et al., J. Immunol. Methods (1989) 119, 117) which permits the specific and quantitative measurement of mouse IgM, IgA and IgG subclasses with one major exception: IgG2a of the b allotype (Igh-1b in mouse strains such as C57BL/6) could not be reliably quantitated even by a very specific and sensitive asymmetrical sandwich ELISA (using two different anti-IgG2a isotype antibodies for capture and for detection). We now describe a similar method based on the use of two different anti-IgG2a allotype antibodies for the capture and detection of IgG2a in the serum of Igh-1b mouse strains.

Animals↗

PubMed1989

Indirect double sandwich ELISA for the specific and quantitative measurement of mouse IgM, IgA and IgG subclasses.

We have developed sensitive enzyme-linked immunosorbent assays (ELISA) which measure mouse serum heavy chain immunoglobulin isotypes in nanograms per milliliter. In each case the specific isotypic Ig is sandwiched between an isotype-specific antibody used for coating and another isotype-specific antibody coupled to biotin for detection (with alkaline phosphatase coupled to avidin). These methods are simple to perform, specific for each isotype, reproducible with an average coefficient of variation of 5% for IgG1, 3% for IgG2a, 7% for IgG2b, 10% for IgG3, 3% for IgA and 7% for IgM, and at least 100 times more sensitive than radial immunodiffusion. The assays have been used to determine the absolute concentrations of mouse serum heavy chain Ig isotypes.

Animals↗

PubMed1989

The C57BL/6 nude, beige mouse: a model of combined T cell and NK effector cell immunodeficiency.

This article describes the construction and establishment of a double congenic nude, beige C57BL/6 (B6 nu, bg) mouse strain. The mice do not show higher fragility than C57BL/6 nude mice and the double congenic strain can be maintained under conventional mouse housing conditions. Although the B6 nu, bg display a very low natural killer activity which cannot be enhanced by an interferon inducer (poly(I-C], they lack responsiveness to a T cell mitogen (concanavalin A); and they also show extremely low responsiveness to a B cell mitogen (0128: B12 Escherichia coli lipopolysaccharide) probably as a result of combined effects of the beige and nude genes in the C57BL/6 genetic context.

Animals↗