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Biomedical subjects

S Mackinnon

Publications and source records attributed to S Mackinnon.

At least 19 recordsLinked to original sources
PubMed2001

Induction of cytomegalovirus (CMV)-specific T-cell responses using dendritic cells pulsed with CMV antigen: a novel culture system free of live CMV virions.

Recipients of allogeneic transplants are at risk of cytomegalovirus (CMV) infection and disease during the period of immune compromise after transplantation. The limitations of current antiviral pharmacotherapy have led to attempts to develop alternative strategies for preventing or treating CMV infection, such as adoptive transfer of donor-derived virus-specific T cells. Methods for generating CMV-specific T cells either use live CMV to infect autologous antigen-presenting cells (APCs) or require some knowledge of the immunodominant peptides involved in the immune response. A novel culture system was developed that does not use live virions and in which the APCs are monocyte-derived dendritic cells (DCs). APCs were pulsed with CMV antigen and cocultured with autologous peripheral blood lymphocytes from donors seropositive for CMV. The culture-output cells consisted of both CD4- and CD8-expressing T cells. Proliferation, as determined by a tritium-thymidine-incorporation assay, showed significant CMV-antigen specificity in cultures from 15 of 15 donors seropositive for CMV. In cytotoxicity assays, cytotoxic T lymphocytes from 10 of 12 cocultures specifically lysed autologous CMV-infected fibroblasts or DCs but not HLA-mismatched or uninfected target cells, and this activity was shown to be blocked by HLA class 1 blocking antibodies. T-cell-receptor spectratyping of cells from the cultures typically showed complex size-distribution patterns, with all size classes of a normal preculture distribution present. However, a few size-class peaks were expanded compared with the preculture patterns and these may have represented expansions of CMV-specific T-cell clones. Advantages of this culture system are that it requires no live virions and no detailed knowledge of the antigenic peptides involved and it is applicable to CMV-seropositive donors of any HLA type.

Antibodies, Viral↗
PubMed2000

In vivo CAMPATH-1H prevents graft-versus-host disease following nonmyeloablative stem cell transplantation.

A novel nonmyeloablative conditioning regimen was investigated in 44 patients with hematologic malignancies. The median patient age was 41 years. Many of the patients had high-risk features, including 19 patients with a previous failed transplant. Recipient conditioning consisted of CAMPATH-1H, 20 mg/day on days -8 to -4; fludarabine, 30 mg/m(2) on days -7 to -3; and melphalan, 140 mg/m(2) on day -2. Thirty-six recipients received unmanipulated granculocyte colony-stimulating factor-mobilized peripheral blood stem cells from HLA-identical siblings, and 8 received unmanipulated marrow from matched unrelated donors. GVHD prophylaxis was with cyclosporine A alone for 38 patients and cyclosporine A plus methotrexate for 6 sibling recipients. Forty-two of the 43 evaluable patients had sustained engraftment. Results of chimerism analysis using microsatellite polymerase chain reaction indicate that 18 of 31 patients studied were full-donor chimeras while the other patients were mixed chimeras in one or more lineages. At a median follow-up of 9 months (range 3 to 29 months), 33 patients remain alive in complete remission or with no evidence of disease progression. Seven patients relapsed or progressed post-transplantation, and 4 of them subsequently died. Four patients died of regimen-related complications. There were no cases of grades III-IV acute GVHD. Only 2 patients developed grade II acute GVHD, and only 1 had chronic GVHD. The estimated probability of nonrelapse mortality was 11%. Although longer follow-up is needed to establish the long-term remission rates, this study demonstrates that this nonmyeloablative preparative regimen is associated with durable engraftment, minimal toxicity, and low incidence of GVHD.

Adolescent↗
PubMed2000

Longitudinal monitoring of immune reconstitution by CDR3 size spectratyping after T-cell-depleted allogeneic bone marrow transplant and the effect of donor lymphocyte infusions on T-cell repertoire.

Delayed immune reconstitution after allogeneic bone marrow transplantation (BMT) with associated infection is a major cause of morbidity and mortality. We used third complementarity region (CDR3) size spectratyping as a tool for monitoring T-cell repertoire reconstitution in 19 patients over a median time of 40 months after T-cell-depleted allogeneic BMT for chronic myeloid leukemia (CML). Furthermore, the effect of donor lymphocyte infusions (DLI) for the treatment of relapse in 18 of the 19 patients was analyzed. All BMT recipients had irregular spectratypes in the first 3- to -6 months after transplant. These evolved to more normal patterns by 12 months after transplant and continued to improve thereafter. In approximately a third of the patients, it took 2 to 3 years for all spectratypes to normalize, whereas in the other two thirds, some abnormal spectratypes persisted even after several years. In 9 patients, there was no immediate change in the CDR3 size profiles after DLI. In 3 patients, spectratypes improved slightly after DLI, whereas in 6 patients, spectratypes became more restricted and irregular. Overall, T-cell spectratypes in BMT patients were characterized by instability over time and in patients with graft-versus-host disease (GVHD), this was even more exaggerated. Several factors, such as pre-BMT conditioning, T-cell depletion of the donor marrow, loss of thymic function in adults, exposure to infectious agents, GVHD, and immunosuppressive treatment, are likely contributors to the delay in T-cell-repertoire reconstitution. (Blood. 2000;95:3990-3995)

Adolescent↗
PubMed2000

One antigen mismatched related donor bone marrow transplant in a patient with acute lymphoblastic leukaemia and beta-thalassaemia major: potential cure of both marrow disorders.

We report a case of a 34-year-old man with T-ALL and beta-thalassaemia major who underwent a one antigen mismatched related donor bone marrow transplant. Five months post transplant chimeric studies revealed full donor haemopoiesis and the patient remains leukaemia and thalassaemia free at 12 months post transplant. Cumulative risk factors contributing to the increased transplant-related mortality in patients with two different marrow disorders are discussed.

Adult↗
PubMed2000

MR angiographic diagnosis of cerebral venous sinus thrombosis following allogeneic bone marrow transplantation.

Allogeneic bone marrow transplantation is frequently associated with neurological complications, particularly intracerebral bleeds and infections. Cerebral venous sinus thrombosis has only rarely been reported following allogeneic transplants. We report three cases of cortical venous thrombosis following allografting for acute lymphoblastic leukaemia. Two patients received marrow from HLA-identical siblings and one from an unrelated donor. Two of the patients presented with grand mal seizures and one presented with a headache. No neurological abnormalities were found upon clinical examination and lumbar puncture was normal in all three cases. In two of the patients computed tomography (CT) of the brain was normal and in the third showed non-specific abnormalities. Magnetic resonance imaging (MRI) with MR angiography (MRA) demonstrated cerebral venous sinus thrombosis in all three patients. In conclusion, cerebral venous sinus thrombosis should be considered in the differential diagnosis when neurological symptoms occur following allogeneic bone marrow transplantation. We therefore advocate the use of MRA for unexplained neurological symptoms post-allograft since without it cerebral venous sinus thrombosis may easily be missed.

Adolescent↗
PubMed2000

Cavernosal arterial insufficiency is a major component of erectile dysfunction in some recipients of high-dose chemotherapy/chemo-radiotherapy for haematological malignancies.

We studied 24 male patients aged 26-62 years (median 41) prospectively presenting over a 5 year period with clinical features of hypogonadism and erectile dysfunction (ED), who had been treated with autologous or allogeneic bone marrow/stem cell transplant for a variety of haematological malignancies and had received either high-dose chemotherapy or high-dose chemotherapy combined with total body irradiation (TBI). Ten healthy adult controls (aged 35-50 years) were also studied. Erectile dysfunction (ED) was assessed clinically and by colour flow Doppler studies of the cavernosal vessels. Testicular function was assessed by testicular volume including orchidometry, FSH, LH and testosterone measurements. Libido and ejaculatory function were also recorded. Patients had severe hypogonadism as evidenced by low mean testicular volume (7.0 +/- 2.4 ml vs 20 +/- 2.0 ml; P < 0.001), elevated gonadotrophins (FSH = 18.54 +/- 7.61 vs 5 IU/l (P < 0.001); LH = 8.02 +/- 2.89 vs 3. 9 IU/l (P < 0.001)) and low normal mean testosterone levels (16.4 nmol/l +/- 9.1 vs 22.4 nmol/l (P < 0.5)). Cavernosal arterial insufficiency was found in 11/14 of TBI-treated and in 3/10 HDC-treated patients, indicative of vasculogenic damage to corpora cavernosal vessels. Patients were given a therapeutic trial with testosterone replacement therapy (TRT). Those who had diminished libido had a marked improvement in their symptoms but the effect of TRT on ED was equivocal. In conclusion, this is the first report to show vasculogenic insufficiency in patients with haematological malignancies treated by BMT. Although hypogonadism can account for diminished libido, arteriogenic insufficiency is likely to be an important factor accounting for ED in these patients, especially those treated by TBI. We recommend a comprehensive assessment including endocrine profile and colour flow Doppler study in formulating the best management plan in recipients of high-dose therapy presenting after transplant with ED.

Adult↗
PubMed2000

Nerve dependency in scarless fetal wound healing.

The human fetus is capable of healing cutaneous wounds without scar up to the third trimester of development This process of tissue repair is more akin to newt limb regeneration than classic adult scar forming wound repair. Regeneration of the newt limb is dependent on neural input in its early stages. This study was an attempt to determine whether a similar dependence on neural input exists for mammalian fetal wounds to heal without scar. The left hind limb of six fetal lambs was denervated during the early second trimester of development (day 55; term = 145 days). Two weeks after denervation, the animals were again exposed to create bilateral incisional and 6-mm-diameter excisional wounds on their innervated right and denervated left lower extremities. Five days after creation of these defects, the wounds were examined for alterations in repair. Four fetal lambs survived, and three were suitable for evaluation. There were marked alterations in wound healing seen after denervation. Excisional wounds on the innervated side contracted and decreased their surface area by 14 percent. In contrast, the denervated wounds not only failed to contract, but increased in size by 60 percent. Changes in the incisional wounds were equally distinctive. Innervated incisional wounds healed completely without scar and had a wound breaking strength comparable to that of normal skin (Table I). In contrast, two of the three denervated incisional wounds dehisced and failed to heal, even in the regions where the skin was approximated by suture. The third denervated incisional wound did heal but with a significant amount of scar. Electron microscopy confirmed this finding by clearly demonstrating thickened and irregular collagen deposition in the extracellular matrix of all the denervated incisional specimens. In summary, like the regenerating newt limb, scarless fetal skin wound repair requires neural stimulation for tissue regeneration to occur. Therefore, in the mammal, the primary regulator for this unique type of tissue repair may have a central neural, rather than a local, tissue origin.

Adult↗
PubMed2000

Extended routine polymerase chain reaction surveillance and pre-emptive antiviral therapy for cytomegalovirus after allogeneic transplantation.

Pre-emptive treatment strategies based on sensitive screening for cytomegalovirus (CMV) infection up to day +100 after allogeneic transplantation have been shown to reduce the incidence of CMV disease during the period of surveillance. However, the use of ganciclovir has been associated with delays in immune reconstitution and an increased incidence of late CMV disease after day +100. In the present study, 81 patients undergoing allogeneic transplantation received polymerase chain reaction (PCR)-guided pre-emptive therapy based on detection of CMV DNA by PCR on 2 consecutive weeks up to day +180. Thirty-three of the 52 high-risk patients (CMV-seropositive donor or recipient) received a total of 45 treatment episodes up to day +100. Three of these patients (5.7%) developed CMV disease, with one fatality. Twelve of the surviving 44 high-risk patients (27%) required pre-emptive treatment between days +101 and +192, but none of these patients developed late CMV disease with a median follow-up of 402 d (range 117-952 d). Antiviral therapy was stopped after a single negative PCR result with no subsequent episodes of CMV disease while patients remained off antiviral treatment. As all initial episodes of CMV DNA detection occurred within 60 d of transplantation, it may be possible to discontinue monitoring beyond day +100 in patients who have remained CMV PCR negative before this. Thus, we have confirmed that PCR-guided pre-emptive therapy results in a low incidence of CMV disease before day +100 and that discontinuing treatment on the basis of viral clearance as determined by CMV PCR appears to be safe practice. In addition, we have observed no episodes of late CMV disease with an extension of surveillance to 26 weeks.

Acyclovir↗
PubMed1999

Early PCR-negativity after allogeneic BMT in adults with t(4;11) ALL in the absence of acute or chronic GVHD.

Acute lymphoblastic leukaemia (ALL) with the t(4;11) translocation has a very poor prognosis following conventional chemotherapy. Many patients are offered an allogeneic BMT in first remission. We report on the impact of allogeneic BMT on three patients with t(4;11) ALL in first remission. Median age was 20 years. One patient received marrow from an HLA-identical sibling and the other two from unrelated donors. All three engrafted and none of the patients developed acute or chronic GVHD. Remission status was monitored using a sensitive nested RT-PCR to detect the ALL-1/AF-4 hybrid transcript. All three were PCR-negative at 3 months post-BMT. One of the unrelated recipients died of a fungal infection 4 months post-BMT. The other two are alive and in molecular remission at 21 and 24 months post-BMT. This is the first report of longitudinal follow-up of t(4;11) ALL post-allogeneic BMT by PCR. The early attainment of molecular remission in the absence of GVHD suggests that the conditioning regimen may have been more important than a graft-versus-leukaemia effect in these patients. Follow-up of larger numbers of patients will be required to confirm these preliminary observations.

Acute Disease↗
PubMed1999

A fatal case of autoimmune thrombocytopenia with an IgM anti-GPIb/IX following one antigen mismatched unrelated donor bone marrow transplantation.

We report the case of a 32-year-old patient with ALL who developed autoimmune thrombocytopenia 2 months following allogeneic bone marrow transplantation. An IgM autoantibody against the platelet glycoprotein Ib/IX complex was observed. Treatment with high-dose steroids and intravenous immunoglobulin G failed to produce any benefit and the thrombocytopenia led to fatal gastrointestinal haemorrhage. The possible factors contributing to post-allograft thrombocytopenia and potential management strategies are discussed.

Adult↗
PubMed1999

Fulminant hepatic failure caused by adenovirus infection following bone marrow transplantation for Hodgkin's disease.

Adenoviruses are increasingly realised to be responsible for serious morbidity and mortality following allogeneic bone marrow transplantation. We describe a case of fulminant hepatic failure due to adenovirus serotype 2 in a 39-year-old woman who received a matched sibling allogeneic bone marrow transplant for multiply relapsed Hodgkin's disease. Isolated fulminant hepatic failure caused by this serotype of adenovirus has not previously been described.

Adenoviridae Infections↗
PubMed1999

An unusual case of intrapulmonary granulocytic sarcoma presenting as interstitial pneumonitis following allogeneic bone marrow transplantation for acute myeloid leukaemia and responding to donor lymphocyte infusion.

We report a 45-year-old female with AML who underwent a T cell-depleted sibling allograft and relapsed a year later with extramedullary disease involving the lung parenchyma and presenting with the clinical and radiological features of interstitial pneumonitis. The patient was treated with donor lymphocyte infusion (DLI) resulting in complete resolution of the radiological signs. The unusual presentation and the management options are discussed.

Bone Marrow Transplantation↗
PubMed1998

T-cell-depleted allogeneic bone marrow transplantation as postremission therapy for acute myelogenous leukemia: freedom from relapse in the absence of graft-versus-host disease.

Thirty-one consecutive patients with acute myelogenous leukemia (AML) in first complete remission and 8 with AML in second complete remission received T cell-depleted allogeneic bone marrow transplants from HLA-identical sibling donors. Patients received myeloablative cytoreduction consisting of hyperfractionated total body irradiation, thiotepa, and cyclophosphamide. Those patients at risk for immune-mediated graft rejection received additional immune suppression with antithymocyte globulin and methylprednisolone in the early peritransplant period. Patients with AML who underwent allogeneic T-cell-depleted bone marrow transplantations (BMT) in first or second remission have achieved respective disease-free survival (DFS) probabilities of 77% (median follow-up at approximately 56 months) and 50% (median follow-up at approximately 48 months). Ten of 31 patients transplanted in first remission were > or = 40 years old and have attained a DFS at 4 years of 70%. For patients with AML transplanted in first or second remission, the respective cause-specific probabilities of relapse were 3.2% or 12.5%, and those of nonleukemic mortality were 19.4% or 37.5%. There were no cases of immune-mediated graft rejection and no cases of grade II to IV acute graft-versus-host disease (GVHD). All survivors enjoy Karnofsky performance scores (KPS) of 100%, except 2 patients with KPS of 80% to 90%. T-cell-depleted allogeneic BMT can provide durable DFS together with an excellent performance status in the majority of patients with de novo AML. In addition, GVHD is not an obligatory correlate of the graft-versus-leukemia benefit or freedom from relapse afforded by allogeneic BMT administered as postremission therapy for AML. This study provides a basis for prospective comparison with other postremission therapies considered standard in the management of patients with this disease.

Adolescent↗
PubMed1997

Donor leukocyte infusions.

Donor leukocyte therapy has resulted in a remission rate in excess of 70% in patients with relapse of chronic myeloid leukaemia (CML) following allogeneic bone marrow transplantation (BMT). Induction of remission with donor leukocyte infusions has been primarily successful for CML patients who have cytogenetic relapse or those with chronic-phase haematological relapse. Response rates appear to be lower in patients who have advanced-phase CML. The majority of patients with CML who enter remission have no detectable minimal residual disease when analysed for BCR-ABL mRNA transcripts by reverse-transcription polymerase chain reaction. The efficacy of donor leukocyte infusions and the ease of therapy are balanced by the potential for significant toxicity. The reported treatment-related mortality rate is almost 20%. The major toxicities of this treatment are secondary to marrow aplasia and graft-versus-host disease (GVHD) which may occur in up to 50% and 90% of responders respectively. Donor leukocytes with a T-cell content of only 1 x 10(7)/kg, approximately a factor of 10 fewer T cells than used in most early studies, are capable of inducing remissions in some patients. The use of lower doses of T cells or CD8+ depleted T cells may be associated with less GVHD. The optimal treatment schedule using donor leukocytes has yet to be determined. Factors which might influence outcome include phase of disease, use of interferon alpha, use of unrelated donors and human leukocyte antigen disparity, T-cell dose, CD8+ depletion of leukocytes and time from BMT to leukocyte infusion.

Humans↗
PubMed1996

Specific human cellular immunity to bcr-abl oncogene-derived peptides.

Chronic myelogenous leukemia (CML) cells are characterized by a t(9;22) translocation, which can encode one of two chimeric P210 bcr-abl fusion proteins, comprising products of either the b2a2 or the b3a2 exon junction. The junctional sequences represent potentially immunogenic tumor-specific antigens. Despite their intracellular location, the fusion proteins might be recognized immunologically by T lymphocytes if peptides, derived from these unique sequences, are capable of presentation by the major histocompatibility complex molecules. We previously found that four peptides, 9 to 11 amino acids long, spanning the b3a2 CML breakpoint bind with high or intermediate affinity to purified HLA class I molecules A3, A11, B8, or both A3 and A11. We tested the ability of these peptides to elicit specific class I restricted cytotoxic T lymphocytes (CTLs) in vitro in HLA-matched healthy donors. In addition, a longer b3a2 CML-breakpoint-derived peptide, 25 aminoacids in length (b3a2-25), was studied for its ability to induce peptide-specific, class II-mediated, T-cell proliferation. In four of four HLA-A3 donors tested, CML-A3/A11-peptide specific CTLs were induced that killed an allogeneic HLA-A3-matched peptide pulsed leukemia cell line. In two of three HLA-A3 donors, the CML-A3/A11 peptide was able to induce killing of autologous and allogeneic HLA-matched peptide-pulsed peripheral blood mononuclear cells (PBMC). CML-A3 peptide induced peptide specific CTLs in one of the four HLA A3 donors tested. No killing was observed in two HLA-B8 and two HLA-A11 donors. PBMC from seven donors were also tested for anti b3a2-25 peptide proliferation in a thymidine incorporation assay. Specific proliferation was detected in three donors, all of the HLA-DR11 haplotype. These data represent the first evidence of a cytolytic human immune response against CML bcr-abl oncogene-derived peptides and provide a rationale for developing peptide-based vaccines for this disease.

Amino Acid Sequence↗