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Rapid blood clearance of injected mouse IgG2a in SCID mice.

SCID mice were found to have rapid blood clearance of injected mouse IgG2a antibodies (Ab), while IgG1 Ab were cleared normally. This effect varied depending on the strain of SCID mice, being very rapid in most Taconic ICR mice and slower in C.B-17 mice. A similar effect was previously described in nude mice, and shown to be due to the very low concentrations of endogenous IgG2a and IgG2b in these mice. Therefore, IgG2a and IgG2b concentrations were assayed in sera from 30 SCID mice: the concentrations were very low, with one exception. Rapid blood clearance in all strains could be strongly inhibited by injection of large amounts of irrelevant IgG2a. Therefore, the low endogenous IgG2a and IgG2b concentrations are responsible for the rapid blood clearance rate of injected IgG2a in these mice, as in nude mice. However, the relatively slow blood clearance of injected IgG2a in certain SCID mice (C.B-17 mice and rare Taconic ICR mice), was not generally due to higher levels of IgG2a or IgG2b, but rather to some other factor that has not been identified. F(ab')(2) Ab fragments were not cleared rapidly, which supports other evidence that clearance is via the CD64 Fcgamma receptor. This rapid clearance of IgG2a affects the ability of such Ab to target tumors, and was also shown to affect the maximum tolerated dose (MTD) of radiolabeled IgG2a Ab, labeled with either (125)I or (111)In. Mice with faster blood clearance had a lower MTD, probably due to the fact that Ab uptake was in the bone as well as the spleen. This effect must be taken into consideration in experiments in which SCID mice are injected with IgG2a or IgG2b Ab.

Animals↗

Mechanisms of innate and acquired resistance to Cryptosporidium parvum infection in SCID mice.

SCID mice, which lack T and B cells, were used as hosts to investigate the nature of both T cell-independent and T-cell-dependent immune responses to infection with Cryptosporidium parvum. We found previously that SCID mice developed chronic infections in which the level of oocyst excretion was low up to about eight weeks post-infection but then increased significantly to cause morbidity and death after 13 weeks. In the present study, weekly administration of an anti-IFN-gamma monoclonal antibody (MoAb) resulted in a shortened prepatent time, significant increase in oocyst excretion and early onset of disease and death. These results suggested an immunologically mediated resistance to C. parvum in the SCID host which required the production of IFN-gamma. Attempts to demonstrate a role for TNF in nonspecific immunity were unsuccessful as injection of mice at weekly intervals with an anti-TNF MoAb failed to alter the course of infection. In contrast to the chronic infection observed in the mice above, SCID mice reconstituted with spleen cells from naive BALB/c mice were able to recover. Depletion of CD4+ cells from the donor population abrogated this protective effect. Mice receiving spleen cells depleted of CD8+ cells were able to recover but the patent infection was prolonged compared with those obtained in mice receiving unfractionated cells. These results demonstrate that CD4+ cells are necessary for the development of immunity to C. parvum infection in reconstituted SCID mice, but, in addition, that CD8+ cells also make a significant contribution to this immunity.

Animals↗

Reduced sensitivity to and ras mutation spectrum of N-ethyl-N-nitrosourea-induced thymic lymphomas in adult C.B-17 scid mice.

Scid mice are defective in the ability to repair DNA double strand breaks and, as a consequence, their cells are radiosensitive. Further, they have been shown to be prone to develop thymic lymphomas (TLs) after small doses of ionizing radiation. Little is known, however, on the role of scid mutation in chemical carcinogenesis. To determine if scid mutation increased predisposition to chemical carcinogenesis, we examined both the susceptibility of scid mice to N-ethyl-N-nitrosourea (ENU)-induced lymphomagenesis and the involvement of ras gene activation. Adult female mice at 8 weeks of age were given ENU in their drinking water at 400 ppm for 2-10 weeks. Contrary to expectations, we observed a two to three-fold reduction in TL development in the scid mice. The highest incidence was achieved by ENU treatment for 8 weeks for scid and wild-type C.B-17 mice, of 42 and 85%, respectively (P<0.05). We investigated whether this was attributable to the usage of the ras mutation pathway. There was, however, no significant difference in the frequency and spectrum of K-ras mutation between the scid and wild-type C.B-17 mice. Most of the K-ras mutations were either GGT to GAT transition in codon 12 (11/23: 48%) or CAA to CCA transversion in codon 61 (8/23: 35%) that was independent of scid background. The incidence of N-ras mutation was very low. These results indicate that scid mice are less susceptible to ENU-induced lymphomagenesis and ras gene mutation frequently occurs in both scid and wild-type C.B-17 mice.

Animals↗

Effect of orally administered monoclonal antibody on persistent Cryptosporidium parvum infection in scid mice.

Scid mice, persistently infected after exposure to 10(7) Cryptosporidium parvum oocysts, were treated daily for 14 to 17 days with 0.4 mg of monoclonal antibody (mAb) 17.41 administered by the oral route. Mice receiving mAb 17.41 shed significantly fewer (P < 0.005) C. parvum oocysts than scid mice receiving isotype control mAb. Intestinal (but not gastric) infectivity scores were also reduced for scid mice treated with mAb 17.41 (P < 0.01).

Administration, Oral↗

Effect of sublethal total body irradiation on acute graft-versus-host disease and graft-versus-leukemia effect in SCID mice.

SCID mice were transplanted with H-2-incompatible C3H/He splenocytes with or without previous TBI with 2Gy to evaluate the influence of sublethal TBI on GVHD and on the graft-versus-leukemia (GVL) effect. Transplantation immediately after TBI induced lethal GVHD, but delayed donor leukocyte infusion (DLI) 5 days after TBI reduced the severity of the GVHD. SCID mice inoculated with L1210 cells after TBI received a DLI 5 days after TBI to induce the GVL effect. Survival of these mice was longer than that of control nonirradiated mice. Serum levels of tumor necrosis factor-alpha, IL-1alpha, IL-6, IL-2 and IFN-gamma were significantly elevated, and they reached maximum levels at 5 days post-transplantation. Except for IFN-gamma, all cytokine levels were higher in irradiated mice than those in nonconditioned mice. Cytotoxicity against L1210 cells mediated by splenocytes from irradiated recipients was greater than that mediated by effector cells from nonirradiated mice. All the irradiated mice survived more than 120 days after L1210 rechallenge, while all nonirradiated mice died of leukemia within 5 weeks. In conclusion, compared with control mice infused with donor splenocytes without previous TBI, SCID mice which received sublethal TBI and DLI showed superior cytotoxicity against L1210 cells and survived longer without severe GVHD.

Acute Disease↗

Low frequency of Ras gene mutation in spontaneous and gamma-ray-induced thymic lymphomas of scid mice.

Scid mice, which have a defect in the capacity to repair DNA double-strand breaks, were highly prone to the induction of thymic lymphomas after exposure to ionizing radiation; approximately 70% of mice developed lymphomas within 1 year after exposure to 1-3 Gy, whereas approximately 20% of unirradiated control mice developed lymphomas. To gain information on the possible role of Ras activation in development of thymic lymphomas in scid mice, we have examined both the frequency and the spectrum of Kras and Nras mutations in spontaneous and radiation-induced lymphomas. Neither activated Kras nor Nras genes were detected in spontaneous lymphomas, while Kras mutations increased in a dose-dependent manner in radiation-induced lymphomas. However, Kras mutations were infrequent (6% in lymphomas in mice exposed to 1 Gy, 12.5% in those exposed to 2 Gy, 16.7% in those exposed to 3 Gy), and no mutations were detected in Nras genes, suggesting that Ras mutation was not significantly involved in the development of thymic lymphomas in scid mice. Analysis of the spectrum of Kras mutations demonstrated unique mutations in both codons 13 (GGC to GAC) and 61 (CAA to CTA) in addition to the commonly identified substitution of GAT for GGT in codon 12 of Kras.

Animals↗

Occurrence of mature B (IgM+, B220+) and T (CD3+) lymphocytes in scid mice.

Scid mice with and without detectable serum Ig (scid Ig+ and scid Ig- mice, respectively) were examined for the presence of mature "leaky" lymphocytes by flow microfluorimetry with the use of antibodies to B (IgM, B220) and T (CD3, CD4, CD8) lymphocyte surface Ag. The data showed that leaky scid mice are more frequent than is evident from serum Ig analysis and that the incidence of detectable B and T cells increases with age. IgM+ B220+ cells were not detectable in young adult mice (3 mo old), but in old mice (greater than or equal to 1 yr old) they were routinely present in the peritoneal cavity though not in the spleen. Striking differences in the representation of T cell subsets were seen in the thymus of these two age groups. Most young adult mice contained CD3- populations of CD4/CD8 double positive cells, and in some cases, CD4 or CD8 single positive cells as well. By contrast, identifiable T lineage cells in old mice were all CD3+ and predominantly single positive for CD4 or CD8. Detectable peripheral T cell populations numbered less than 10(5) cells, and the representation of T subset markers (CD4, CD8) varied widely among individual mice; further, Southern blot analysis of TCR gene rearrangements in the DNA of polyclonally stimulated lymphoid cultures from these mice showed very restricted heterogeneity relative to that of cultures from normal mice. We conclude that most leaky mice contain very few T cell clones.

Aging↗

House dust mite-induced airway changes in hu-SCID mice.

SCID (severe combined immunodeficiency) mice reconstituted with peripheral blood mononuclear cells (PBMC) from Dermatophagoides pteronissynus (Dpt)-sensitive patients and exposed to Dpt aerosol (allergic hu-SCID mice) develop human IgE and pulmonary inflammation. The present study investigated concomitant changes in airway hyperresponsiveness (AHR). No significant difference in baseline airway responsiveness was seen between nonreconstituted SCID mice exposed or not to Dpt aerosol at Day 35. Allergic hu-SCID mice developed AHR (provocative dose of carbachol causing a 50% increase in lung resistance [PD(50) RL] = 96.33 +/- 16.88 microg/kg) compared with nonallergic hu-SCID mice (PD(50) RL = 242.03 +/- 37.84 microg/kg) and nonreconstituted SCID mice (PD(50) RL = 297.60 +/- 45. 60 microg/kg) exposed to Dpt aerosol. An inverse correlation was observed between PD(50) RL (Day 35) and total human IgE at Day 7 (r = -0.58) and Day 15 (r = -0.64). However, no correlation existed between PD(50) RL and human cell number in the lungs of allergic hu-SCID mice. Moreover, despite the absence of eosinophils, the bronchoalveolar lavage fluid (BALF) of allergic hu-SCID mice had more human interleukin-5 (IL-5) (3.28 +/- 0.40 pg/ml, n = 13) than nonallergic hu-SCID mice (< 0.5 pg/ml) which inversely correlated with the PD(50) RL (r = -0.61). No tumor necrosis factor-alpha (TNF-alpha), IL-6, or IL-4 was detected. These observations indicate that humanized allergic hu-SCID mice may develop AHR after exposure to the relevant allergen, suggesting that this model may improve our understanding of AHR, one characteristic feature of allergic asthma.

Airway Resistance↗

EBV-specific cytotoxic T lymphocytes protect against human EBV-associated lymphoma in scid mice.

Scid mice develop human EBV-positive B cell tumors after injection with EBV-transformed human B cells or peripheral blood lymphocytes from EBV-seropositive donors. Injection of cytotoxic T cell (CTL) lines, selectively expanded in vitro to recognize autologous EBV-transformed B cells, protected mice against developing human lymphoproliferative disease. CTL protection required a single dose of polyethylene-glycol-conjugated IL2. Mice were not protected by CTL that did not specifically recognize EBV-transformed B cells or by mitogen-activated lymphocytes.

Adoptive Transfer↗

Inhibitory effect of simvastatin on the proliferation of human myeloid leukaemia cells in severe combined immunodeficient (SCID) mice.

SCID mice were inoculated intravenously with cells from the human HL60 myeloblastic leukaemia cell line and then treated with the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor, simvastatin, by subcutaneous continuous infusion. The effect of the drug was measured by subsequent colony formation of surviving HL60 cells in vitro and flow cytometry. The number of clonogenic HL60 cells was reduced in the bone marrow of mice that received simvastatin compared with control mice by 65% and 68% in two separate experiments. The number of clonogenic, normal, murine, bone marrow progenitor cells concomitantly exposed to simvastatin in vivo, was not affected in either experiment. Flow cytometric analysis of bone marrow and spleen cells confirmed these results by showing that simvastatin had reduced the percentage of human leukaemia cells in these tissues by 70% and 88% respectively. The data show that the reported selective effect of simvastatin against acute myeloid leukaemia cells in vitro, can be extended to this in vivo model. HL60 bears an N-ras mutation. In further in vitro studies, ketoconazole, an inhibitor of cholesterol biosynthesis post farnesyl pyrophosphate synthesis, had a similar effect to simvastatin on HL60 colony development. Furthermore, the clonogenicity of a population of N-ras mutated, primary acute myeloid leukaemia (AML) cells was no more sensitive to simvastatin than a population without the mutation. The data suggest that the inhibition of AML cell proliferation by simvastatin may be independent of the RAS signalling pathway.

Acute Disease↗

Engraftment of bovine leukemia virus infected lymphocytes into SCID mice.

SCID mice inoculated with peripheral blood lymphocytes from a tumor-bearing BLV-positive cow developed lymphosarcomas after 6 months. DNA from the splenic tumor specifically hybridized with a bovine Sstl satellite probe, showing that these tumor cells were of bovine origin. The clonality of the SCID splenic tumor, as measured by the integration pattern of BLV proviruses, was the same as that in the donor lymphocyte population.

Animals↗

Systemic characteristics of chronic arthritis induced by transfer of human rheumatoid synovial membrane into SCID mice (human/murine SCID arthritis).

Erosive human/murine (hu/mu) SCID arthritis, caused by unilateral engrafting of human rheumatoid arthritis synovial membrane (RA-SM) in the knee joints of SCID mice, was monitored for up to 18 weeks by scintigraphic, radiological, morphological and immunohistochemical analyses.(99m)Tc-DPD scintigraphy and histology revealed secondary, oligoarticular spreading of arthritis to contralateral knees and hips, but not to forelimb joints. Also, there were no extraarticular manifestations. At 18 weeks, surviving human cells were found within the pannus, but not directly at the cartilage erosion front, where fibroblast-like cells and macrophages of murine origin predominated. The latter cells also predominated in secondarily affected joints, where no human cells were detectable. Preventive depletion of murine NK-cells by anti-asialo-GMI antibodies, to check the influence of NK cells independently of strain and MHC system, combined with application of autologous human PBMN cells, had virtually no effects on the disease process. The completeness of the SCID defect was not critical, i.e. T cells were completely absent in the organs examined, and the presence of a few B cells in the spleen did not correspond to particular disease features. The SCID defect itself had a clear impact, since, in the chronic phase, SCID.bg and RAG-2(-/-)knockout mice developed less consistent pathological/scintigraphic signs of disease than SCID mice. Thus, unilaterally-induced hu/mu SCID arthritis is an oligoarticular disorder of the hindlimbs. Murine macrophages and fibroblast-like cells appear responsible for tissue destruction in engrafted and non-engrafted arthritic joints.

Animals↗

[Reconstitution of Hu-SCID mice transplanted with human tonsillar lymphocytes immunized with dengue virus-2 in vitro and its immune response].

OBJECTIVE: To study the measure for the reconstitution of severe combined immunodeficient disease mice (SCID mice) transplanted with human lymphocytes immunized with specific antigen in vitro. METHODS: Hu-SCID mice were constructed by intraperitoneal (i.p.) transfer of human tonsillar lymphocytes (TLC) first immunized with dengue virus-2 (DV2) in vitro, then boostered with different doses of DV2 antigen in vivo. RESULTS: Human immunoglobulin (Ig) and specific human anti-DV2 antibodies could be detected in sera of the hu-SCID mice by ELISA. Two weeks after transplantion of the in vitro-immunized hu-TLC, the highest human IgG concentration was 412.86 micrograms/ml, two or four weeks later specific human anti-DV2 IgM or IgG and the neutralizing antibody could found in these sera, respectively, the highest titer was 1:6400. The levels of human IgG and human anti-DV2 antibodies were related to the dose of DV2 antigen. The presence of human B cells (CD20+) and T/cells (CD3+, CD4+, CD8+) were shown in the sleen, lung, intestine and mesentery of the hu-SCID mice as determined by immunoperoxidase staining, and the cells were distributed correspondingly with the lymphocyte cells in proper human tissue. Human anti-DV2 IgG could also be detected in the spleen cell culture obtained from the SCID mice. CONCLUSION: By co-immunized in vitro and in vivo the SCID mice deduced stronger immune response for specific antigen, and the reconstitution of the human lymphocytes could be established successfully.

Animals↗

High efficiency of muscle regeneration after human myoblast clone transplantation in SCID mice.

SCID mouse tibialis anterior muscles were first irradiated to prevent regeneration by host myoblasts and injected with notexin to damage the muscle fibers and trigger regeneration. The muscles were then injected with roughly 5 million human myoblasts. 1 mo later, 16-33% of the normal number of muscle fibers were present in the injected muscle, because of incomplete regeneration. However, > 90% of these muscle fibers contained human dystrophin. Some newly formed muscle fibers had an accumulation of human dystrophin and desmin on a part of their membrane. Such accumulations have been demonstrated at neuromuscular junctions before suggesting that the new muscle fibers are innervated and functional. The same pool of clones of human myoblasts produced only < or = 4% of muscle fibers containing human dystrophin when injected in nude mice muscles. Several of the human myoblasts did not fuse and remained in interstitial space or tightly associated with muscle fibers suggesting that some of them have formed satellite cells. Moreover, cultures of 98% pure human myoblasts were obtained from transplanted SCID muscles. In some mice where the muscle regeneration was not complete, the muscle fibers containing human dystrophin also expressed uniformly HLA class 1, confirming that the fibers are of human origin. The presence of hybrid muscle fibers containing human dystrophin and mouse MHC was also demonstrated following transplantation. These results establish that in absence of an immune reaction, transplanted human myoblasts participate to the muscle regeneration with a high degree of efficacy even if the animals were killed only 1 mo after the transplantation.

Animals↗

Simplified method of identifying severe combined immunodeficient (SCID) mice versus non-SCID mice by flow cytometric analysis of peripheral blood.

Several studies have utilized simple breeding strategies to create new immunodeficient mouse strains from severe combined immunodeficient (SCID) mice and non-SCID mice with secondary traits in order to evaluate the involvement of lymphocytes and immune responses in a variety of processes. We utilized a breeding strategy with C.B-17scid/scid (SCID) (H-2d) mice and SJL (H-2s) mice to generate immunodeficient mice that were histocompatible with the inbred SJL strain (H-2s) in order to evaluate the role of histocompatible recipient lymphocytes in adoptively transferred autoimmune disease mediated by SJL T lymphocytes. [SCID x SJL]F1 mice (heterozygous for H-2 loci and heterozygous for the SCID mutation) were backcrossed with SCID mice and the resulting offspring expressed a variety of phenotypes, including SCID or non-SCID and H-2s/H-2d or H-2d/H-2d. In order to screen offspring for the desired phenotype (SCID, H-2s), a flow cytometric method utilizing forward- and side-scatter parameters of peripheral blood cells was used to distinguish SCID from non-SCID animals. This method simplified the screening process and was as reliable as anti-CD3 fluorescent monoclonal antibody staining for detecting the presence (non-SCID) or absence (SCID) of T lymphocytes in peripheral blood.

Animals↗

Human adult tonsil xenotransplantation into SCID mice for studying human immune responses and B cell lymphomagenesis.

OBJECTIVE: To generate a human-mouse xenochimeric model where human cells remain clustered in the animal to optimize their interactions and recovery. MATERIALS AND METHODS: Severe combined immune deficient mice (SCID) were xenografted subcutaneously with human adult tonsil pieces (hu-ton-SCID mice). Such animals were: (a) compared with those receiving tonsil cells in suspension, and (b) immunized with de novo and recall antigens. RESULTS: Human tonsil pieces survived a long period of time in SCID mice, while polyclonal human T- and B-lymphocytes persisted in close vicinity within the implantation area; however, little or no graft-versus-host disease was detectable. Not surprisingly, local development of lymphoproliferative disease was often observed in animals receiving lymphoid implants from donors previously infected by the Epstein-Barr virus. One month after surgery, higher serum levels of human IgG were found in SCID mice transplanted with tonsil pieces (2x10(7) cells/animal) than in animals injected with 5x10(7) tonsil cells in suspension (1.9 vs. 0.3 mg/mL, p < 0.002). Importantly, the production of human IgG in hu-ton-SCID mice remained polyclonal for at least 6 months and was linked to the presence of cells within the implants. Immunization of hu-ton-SCID mice with hepatitis B core, a de novo antigen, did not produce a significant IgG immune response; however immunization with tetanus toxoid (TT), a thymus-dependent recall antigen, yielded high (> 700-fold increase in anti-TT IgG levels) and long-lasting (> 6 months) secondary immune responses. CONCLUSION: The hu-ton-SCID mouse xenochimeric model described in this report may improve our understanding of human lymphoid cell interactions, secondary immune responses, and lymphomagenesis.

Adult↗

Growth of human T-cell lineage acute leukemia in severe combined immunodeficiency (SCID) mice and non-obese diabetic SCID mice.

Primary leukemic cells from patients with acute lymphoblastic leukemia (ALL) can be injected intravenously into mice with severe combined immunodeficiency (SCID) to create a model of human leukemia. Leukemic cells disseminate to murine tissues in a clinicopathologic pattern similar to that seen in humans. Thus far, reports of engraftment of lymphoid leukemia in SCID mice have mainly been from patients with B-cell lineage ALL, for which engraftment occurs more frequently with cells from high-risk patients. There are few data on the engraftment of T-cell lineage ALL in SCID mice. Leukemic cells from 19 patients (16 adult and three pediatric) with T-cell lineage ALL were injected into SCID mice, with overt engraftment of 12 cases (63%). Engraftment of leukemia in SCID mice was associated with earlier death due to leukemia of the patient donors (P < .01, log-rank test). The recently developed non-obese diabetic (NOD)/SCID mouse may expand the uses of the SCID model. Cells from the seven patients with T-cell lineage ALL that failed to cause leukemia in SCID mice were injected into NOD/SCID mice. Overt leukemia engraftment was observed in all seven cases. Thus, growth of human T-cell lineage ALL cells in SCID mice was associated with a high-risk patient group. However, this association was not observed when NOD/SCID mice were used, suggesting that this model would no longer predict patients likely to die early of leukemia, but may provide a more realistic system for studying the biology and treatment of the disease.

Acute Disease↗