Chronic ataluren (PTC124) treatment of nonsense mutation cystic fibrosis

In a subset of patients with cystic fibrosis (CF), nonsense mutations (premature stop codons) disrupt production of full-length, functional CF transmembrane conductance regulator (CFTR). Ataluren (PTC124) allows ribosomal readthrough of premature stop codons in mRNA. We evaluated drug activity and safety in patients with nonsense mutation CF who took ataluren three times daily (morning, midday and evening) for 12 weeks at either a lower dose (4, 4 and 8 mg·kg(-1)) or higher dose (10, 10 and 20 mg·kg(-1)). The study enrolled 19 patients (10 males and nine females aged 19-57 yrs; dose: lower 12, higher seven) with a classic CF phenotype, at least one CFTR nonsense mutation allele, and an abnormal nasal total chloride transport. Both ataluren doses were similarly active, improving total chloride transport with a combined mean change of -5.4 mV (p<0.001), and on-treatment responses (at least -5 mV improvement) and hyperpolarisations (values more electrically negative than -5 mV) in 61% (p<0.001) and 56% (p = 0.002) of patients. CFTR function was greater with time and was accompanied by trends toward improvements in pulmonary function and CF-related coughing. Adverse clinical and laboratory findings were uncommon and usually mild. Chronic ataluren administration produced time-dependent improvements in CFTR activity and clinical parameters with generally good tolerability.

Transplantation of allogeneic or xenogeneic bone marrow within the donor stromal microenvironment

Successful engraftment of hematopoietic stem cells requires a supportive hematopoietic stromal microenvironment (HSM). Defects in the HSM associated with aplastic anemia, myelofibrosis, or caused by intensive ionizing radiation and chemotherapy generally result in failure of bone marrow (BM) engraftment. Transplantation of donor BM within donor HSM may therefore provide optimal conditions for allogeneic BM transplantation. We have transplanted donor hematopoietic cells together with their own HSM to improve acceptance of allogeneic or xenogeneic BM. The non-myeloablative treatment used induced tolerance to murine allografts and provided conditions for the life-long acceptance of allogeneic HSM. Allogeneic BM transplanted within it's own HSM under the kidney capsule caused less graft-versus-host disease than BM transplanted i.v. Tolerance in mice to xenogeneic (rat) HSM was less complete. Ectopic ossicles were small and contained fewer hematopoietic cells. However, simultaneous transplantation of rat BM and HSM to preconditioned mice improved engraftment of rat BM compared with transplantation of BM alone. Donor hematopoietic cells survived longer on their own HSM than on HSM of recipients.

Allogeneic cell-mediated immunotherapy for eradication of minimal residual disease: comparison of T-cell and IL-2 activated killer (LAK) cell-mediated adoptive immunotherapy in murine models

In the course of allogeneic bone marrow transplantation (BMT), avoiding graft-versus-host disease (GVHD) while retaining the antileukemic effects of the T cells remains a major challenge. T-cell depletion (TCD) reduces the incidence of GVHD but increases the relapse rate after allogeneic BMT. We attempted to develop a regimen that would retain or increase the graft-versus-leukemia effect induced by donor T cells while preventing GVHD. Immunosuppressed mice were given immunocompetent donor cells, i.e., fresh lymphocytes or lymphokine-activated killer (LAK) cells differing from the host in major (MHC) or minor (MiHC) histocompatibility antigens. Engraftment of donor cells was documented by polymerase chain reaction analysis. Administration of MHC- and MiHC-incompatible allogeneic LAK cells, especially in conjunction with recombinant interleukin-2 (rIL-2), increased disease manifestations and mortality associated with GVHD. On the other hand, irradiated LAK cells or TCD-LAK cells prevented GVHD in both mice models studied. Phenotypic analysis of LAK cells demonstrated that CD8(+)-equivalent (Lyt-2) T cells are of significance in aggravation of GVHD. The in vitro cytotoxic capacity of LAK cells against MHC-nonrestricted target cells was not reduced by either irradiation or TCD. These results provide the background for designing improved protocols for immunotherapy of residual disease after BMT. In addition, the data imply that antitumor effects may be retained by irradiated rIL-2-activated allogeneic cells without causing GVHD. Whereas unmodified allogeneic LAK cells can induce more effective graft-versus-leukemia effects at the cost of GVHD, irradiated allogeneic donor LAK cells might play some role in eradication of minimal residual disease following autologous or allogeneic BMT without causing GVHD.

Allogeneic cell-mediated and cytokine-activated immunotherapy for malignant lymphoma at the stage of minimal residual disease after autologous stem cell transplantation

Immunocompetent donor-derived T lymphocytes play a crucial role in the elimination of residual leukemic cells post allogeneic bone marrow transplantation. Because this graft versus leukemia (GVL) effects is absent after autologous stem cell transplantation (ASCT), a high rate of relapse ensues. We introduced cell-mediated immunotherapy at the stage of minimal residual disease in lymphoma patients to help effect a GVL-like reaction by adoptive transfer of immunocompetent human leukocyte antigen-matched donor peripheral blood lymphocytes (PBL). Thirteen consecutive patients with high-risk lymphoma were treated with allogeneic cell therapy (AlloCT) after having undergone ASCT. In the absence of graft-versus-host disease, cell therapy-induced graft-versus-lymphoma reaction was amplified by human recombinant interleukin 2 (rIL-2) during 3 days to activate donor PBL in vivo, followed by infusion of in vitro rIL-2 activated donor lymphocytes combined with 3-day rIL-2 therapy. Nine of the patients underwent the treatment protocol well. In the four other patients, in whom the AlloCT resulted in marrow aplasia due to elimination of host hematopoietic cells, treatment with donor marrow cell infusion without further conditioning was performed. Adoptive cell therapy in the form of AlloCT may turn out to be an effective therapeutic modality for the treatment of resistant residual disease in lymphoma patients.

Tumorigenicity and immunogenicity in a murine model of B-cell leukemia/lymphoma (BCL1)

Multiple injections of intact irradiated BCL1 cells, a murine B-cell leukemia/lymphoma can trigger a dose-dependent anti-tumor immune response in naive syngeneic mice. The ability to induce anti-BCL1 immunity and the effect of various cell-modifications on BCL1 tumorigenicity and immunogenicity was evaluated. Newcastle disease virus (NDV) infection or transfer of cytokine genes by both retroviral and Adeno 5 vectors affect neither tumorigenicity nor immunogenicity of BCL1 cells given as a non-immunogenic cell-dose. New ways will have to be developed to elicit a reliable and reproducible anti-tumor effect in spontaneously arising and non-immunogenic hematological malignancies.

Bone marrow transplantation from a cadaveric donor

A 2.5-year-old girl with neurogenic Gaucher's disease was transplanted with donor bone marrow from her HLA-compatible 12-year-old brother whose marrow was harvested 30 min post-mortem, after he suffered a severe head and neck injury. The marrow was stored in liquid nitrogen for 30 days prior to infusion. The post-transplantation period was uneventful with good engraftment and no signs of graft-versus-host disease. Currently, 6 months post-allogeneic bone marrow transplantation (alloBMT), analysis of both bone marrow and blood samples by PCR documented only cells of donor origin. This case demonstrates the feasibility of cadaveric marrow as a source of donor cells. To our knowledge, this patient is the only survivor of alloBMT from a cadaveric donor.

Donor lymphocyte infusions to displace residual host hematopoietic cells after allogeneic bone marrow transplantation for beta-thalassemia major

PURPOSE

Donor lymphocyte infusion (DLI) was used to reverse relapse after allogeneic bone marrow transplantation (BMT) in a patient with beta-thalassemia major.

PATIENTS AND METHODS

The patient with unstable mixed chimerism after BMT was treated with graded increments of donor lymphocytes (10(5) T cells/kg to 5 x 10(7) T cells/kg) to displace residual hematopoietic host cells.

RESULTS

DLI resulted in complete donor-derived reconstitution of the hematopoietic compartment. The patient developed mild graft-versus-host disease (GVHD) that could be controlled by steroid treatment.

CONCLUSIONS

This case report shows that DLI can effectively eradicate host stem cells in mixed chimeras after BMT in nonmalignant hematopoietic diseases.

Induction of graft vs. tumor effect in a murine model of mammary adenocarcinoma

We have attempted to induce immune-mediated graft-vs.-tumor (GVT) effects against solid tumors, using a murine model of mammary adenocarcinoma derived from BALB/c(H-2d) mice. A cell line (4Tl) isolated from this tumor model was highly tumorigenic in syngeneic (BALB/c) or haplo-identical (BALB/c x C57B1/6)F1 mice (F1), was only partially tumorigenic in an H-2d congenic strain of mice (DBA/2) and was non-tumorigenic in a major histocompatible (MHC)-unrelated (H-2b) strain of mice (C57B1/6). 4Tl cells express class I MHC antigens and adhesion molecules but do not express MHC class II antigens or B7-1 co-stimulatory molecules. Female BALB/c (H-2d) or F1 (H-2d/b) mice were reconstituted with male bone marrow (BM) cells derived from minor histocompatible (MiHC)-mismatched DBA (H-2d) donors or with MHC-mismatched C57B1/6 (H-2b) BM cells, respectively, 24 hr following lethal total body irradiation. Recipient mice carrying MiHC- or MHC-mismatched donor cells were inoculated with 4Tl cells 2-3 months following BM reconstitution. Chimeras reconstituted with allogeneic donor cells that were MiHC- or MHC-incompatible with tumor cells were able to down-regulate the development of the primary tumor expressing host-ype MHC alloantigens. Tumor size in BM chimeras across MiHC or MHC antigens was significantly smaller than tumor size observed in normal BALB/c or F1 controls. The GVT effect might be of help in improving immunotherapy for solid tumors in humans.

Improved single-step PCR assay for sex identification post-allogeneic sex-mismatched BMT

A method is presented which allows sex-identification simultaneously of both male and female cells in cell mixtures. The sensitivity of this PCR-based assay is one male cell in 10(6) female cells. The test can be used routinely to analyze bone marrow and peripheral blood lymphocytes post-allogeneic sex-mismatched bone marrow transplantation to detect early engraftment or rejection, as well as host cell regeneration.

Tumor-cell vaccination induces tumor dormancy in a murine model of B-cell leukemia/lymphoma (BCL1)

Immunity to murine B-cell leukemia/lymphoma (BCL1) induced by multiple injections with irradiated tumor cells, prevented leukemia development in primary and adoptive transfer recipients despite long-lasting persistence of residual tumor cells. Detection of dormant BCL1 cells was carried out by PCR analysis using the VH-rearranged DNA sequence as a BCL1 clonal marker. Dormant tumor cells were detected > 250 days following immunity induction in 40% of spleens from healthy immune mice having no detectable symptoms of disease. Tumor dormancy was not abrogated by adoptive transfer of BCL1-containing splenocytes into syngeneic recipients, indicating that cell-mediated anti-tumor immunity contributes to maintenance of the tumor dormant state and prevents renewed tumor-cell growth. Splenocytes but not sera from immune mice conferred specific radiosensitive protection from a lethal dose of BCL1 cells included in cell mixtures transferred to secondary recipients. A therapeutic effect of transferred immune splenocytes was shown in BCL1-bearing mice, which remained disease-free for > 200 days after inoculation; nevertheless, dormant BCL1 cells were detected by PCR analysis in some of the surviving mice. Our results suggest that an efficient tumor-cell vaccine can lead to induction of tumor dormancy that can be maintained by a cell-derived mechanism for a long period of time.

Minimal residual disease in murine B-cell leukemia (BCL1) detected by PCR

Small proportions of leukemic cells escaping chemo-radiotherapy and/or dormant leukemic cells present in undetectable amounts in patients post therapy, i.e. minimal residual disease (MRD), are a source for relapse. The study of MRD and its treatment in a murine model for human B-cell leukemia/lymphoma, (BCL1), should lead to an improved understanding of the human disease. The standard assay for MRD in experimental mice is the adoptive transfer of spleen cells from experimental animals into naive secondary syngeneic recipients. We describe here the detection of MRD in BCL1-carrying BALB/c mice using the polymerase chain reaction (PCR). A BCL1 specific sequence from the rearranged VH-region was amplified yielding a 456 bp long fragment. PCR products hybridized to the cloned BCL1 sequence allowed the detection of a single BCL1 cell. This assay, therefore, reveals the presence of very small numbers of leukemic cells without sacrificing experimental animals.

Passive immunization of chickens against Eimeria maxima infection with a monoclonal antibody developed against a gametocyte antigen

Eimeria maxima gametocytes contain two major antigens with molecular masses of 56 and 82 kilodaltons (kDa) which are recognized by convalescent sera from immune chickens. Preparations enriched in these two antigens were used to immunize mice, and several monoclonal antibodies which specifically reacted with the 56-kDa antigen were produced. One of these monoclonal antibodies of the immunoglobulin M subclass, along with immune chicken sera raised against affinity-purified 56- and 82-kDa antigens, was used to passively immunize chicks. On the basis of the parameter of total oocyst output, it was found that these antibodies provided partial protection (40 to 50% inhibition) against E. maxima challenge infections.

Eimeria maxima: isolation of gametocytes and their immunogenicity in mice, rabbits, and chickens

Eimeria maxima gametocytes were isolated from infected chicken intestinal tissue by treatment with hyaluronidase and subsequent filtration through polymon filters. The isolated gametocytes were analyzed by microscopical and biochemical methods and shown to be highly enriched. The antigenicity of the gametocytes was analyzed in mice, rabbits, and chickens by ELISA and indirect immunofluorescence. Contrary to published results, we have found gametocytes to be highly immunogenic in all animals tested.

Eimeria maxima: identification of gametocyte protein antigens

The antigenicity of Eimeria maxima gametocyte proteins during the course of an infection and when injected into mice and rabbits was demonstrated using the Western blotting technique. Serum taken from chickens at various times postinfection reacted to a few gametocyte proteins, with the strongest reactivity seen with serum taken 14-days postinfection. Two major antigens having molecular weights of 56,000 and 82,000 were consistently detected by these sera. Using immune rabbit or mouse sera to whole gametocyte detergent extracts, the 56,000 and 82,000 molecular weight proteins were again the immunodominant antigens, despite their representing only a small proportion of the extract which was used to immunize the animals. These results, together with those obtained by Rose (1971) using recovered chicken serum to passively immunize chickens, indicate that these two gametocyte antigens may play a role in protective immunity to E. maxima.

Antigenic proteins of Eimeria maxima gametocytes: cell-free translation and detection with recovered chicken serum

RNA was extracted from isolated Eimeria maxima gametocytes and translated in a rabbit reticulocyte cell-free protein synthesis system. The major cell-free translation products from E. maxima gametocyte RNA ranged from 225 to 50 kDa, distinct and different from uninfected chicken intestine cell-free translation products. Rabbit antiserum to E. maxima gametocytes as well as recovered chicken sera specifically precipitated some of the major gametocyte cell-free products. A time course of infected intestine RNA indicated that these cell-free synthesized gametocyte antigens appear at 130 to 138 hr postinfection.

Identification of a sequence likely to be required for avian retroviral packaging

Two assays have been utilized to assess the ability of avian retroviral molecules to be packaged into virus particles. Cloned viral genomic molecules were microinjected into the nuclei of chick cells infected by either a lymphoid leukosis virus or an envelope glycoprotein-deficient sarcoma virus. The titer of focus-forming virus released by injected cells, or the ratio of these to helper virus, is then used to determine packaging efficiency, although biological properties other than packaging might also effect these assays. With either assay, deletions up to 3.0 kbp introduced in the viral gag or pol genes did not affect packaging unless sequences near the SstII restriction site (approximately 150 bp 3' of the splice donor site) were deleted. Deletions differing by 2 bp at the SstII site were found to express radically different packaging efficiencies.

Analysis by microinjection of the biological effects of site-directed mutagenesis in cloned avian leukosis viral DNAs

Cloned avian leukosis viral DNAs were mutagenized in the long terminal repeat, in the leader sequence for env mRNA, and at the poly-env junction. The effect of these mutations in the viral DNA upon its ability to direct virus production or env mRNA synthesis was analyzed by microinjecting the mutant DNAs into chicken embryo fibroblasts and into chicken cells transformed by the env-deficient Bryan strain of Rous sarcoma virus, respectively. The results indicated that: (i) addition of up to 8 base pairs 19 nucleotides upstream of the Hogness box did not block transcription; (ii) deletion of 26 base pairs, including the tRNA primer binding site, allowed synthesis of all viral products and participation in recombination, but replication was blocked; (iii) deletion of fewer than 50 base pairs 250 bases downstream of the long terminal repeat depressed expression of all viral genes; and (iv) deletion of most of the gag and pol genes did not inhibit env mRNA synthesis, but virion packaging of the unspliced transcript was inefficient.

A thermostable, sequence-specific restriction endonuclease from Bacillus stearothermophilus: BstPI

A restriction endonuclease, BstPI, was purified from a strain of B. stearothermophilus, and its cleavage specificity was determined. The enzyme cleaves at palindromic sites of the general structure: (Formula: see text) where N.N' can be any base pair. It produces phosphorylated 5'-termini which are single stranded over a length of 5 nucleotides. Ends generated by cleavage with BstPI can be rejoined by DNA ligase.