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L D Christensen

Publications and source records attributed to L D Christensen.

At least 19 recordsLinked to original sources
PubMed2001

Extracellular accumulation of bioactive substances during preparation and storage of various platelet concentrates.

BACKGROUND: Side effects of platelet transfusion may be associated with infusion of bioactive substances. We therefore studied extracellular accumulation of histamine, plasminogen activator inhibitor (PAI)-1, vascular endothelial growth factor (VEGF), and interleukin (IL)-6 during preparation and storage of various platelet concentrates. METHODS: Twenty buffy-coat-derived platelet pools (BCPC) were prepared and stored in platelet additive solutions (PAS). Twelve apheresis platelet (APC) units were prepared using the COBE Spectra LRS, and 14 were prepared using the Fenwal Amicus Separator. After preparation half of the content was drawn from each APC unit. The normal ranges of the substances were determined in plasma from all donors, and the extracellular concentrations of the substances were determined in supernatants collected on days 0, 1, 3, 5, and 7 of storage from all platelet preparations. RESULTS: The platelet counts were not significantly different in BCPC units and APC units. The BCPC units had a significantly higher white cell count than the APC units (P < 0.0001), but the count was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.0001). The extracellular histamine concentration was significantly (P < 0.001) increased in BCPC units after preparation and without further increase during storage, while there was no accumulation of histamine in APC units. After preparation the PAI-1 concentration was significantly (P < 0.02) higher in BCPC units than in APC units, but during storage PAI-1 increased significantly (P < 0.05) more in APC units than in BCPC units. Similarly, VEGF concentration was significantly (P < 0.05) higher in BCPC units than in APC units after preparation. During storage, however, VEGF increased more in BCPC units compared with COBE Spectra APC units (P < 0.05), but compared with Amicus Separator APC units only for the first 3 days of storage. At days 5 and 7 of storage the VEGF concentration was significantly higher in the Amicus APC units than in the COBE APC units (P < 0.05). IL-6 was not detectable in any of the concentrates after preparation or during storage. CONCLUSION: Platelet concentrates prepared by the apheresis method may contain less white cell derived bioactive substances than platelet concentrates prepared by the buffy-coat method. However, a substantial storage time dependent platelet derived bioactive substance accumulation takes place in all platelet concentrates tested, presumably due to platelet disintegration.

Adult↗
PubMed2001

Recruitment of CD34+ cells during large-volume leukapheresis.

Mobilized peripheral blood stem and progenitor cells (PBPCs) are increasingly used to restore hematopoiesis after myeloablative treatment. To obtain a sufficient number of CD34(+) cells, many studies have focused on the improvement of the collection technique during the leukapheresis procedure (LP), and so-called large-volume leukapheresis (LVL) procedures have been developed. Such procedures can be performed by extending the duration of the LP and/or by increasing the inlet flow rate. However, no previous studies have compared the efficiency of these procedures. In the present study, we compared the kinetics of PBPCs recruitment (including CD34(+) cell subsets), the PBPCs yield, and the collection efficiency as well as the overall feasibility of the procedures during a single LVL performed by standard (group I) (median 85 ml/min; range 50-97 ml/min) and high inlet flow rates (group II) (median 130 ml/min; range 110-150 ml/min). Seven patients with hematological malignancies were enrolled and allocated to each group. The patients' blood volumes (BV) were processed four times. The apheresis product (AP) was collected in four separate bags, which were changed every time one BV had been processed. The CD34(+) cell number and CD34(+) cell subsets were assessed in the four collection bags and in peripheral blood (PB) before every time one BV had been processed and after the leukapheresis. The CD34(+) cell yield exceeded the pre-apheresis CD34(+) cell number per ml BV in 6 out of 7 patients in group I and in 3 out of 7 patients in group II. In group II, the recruitment of CD34(+) cells from the bone marrow (BM) to PB starts in the second collection period--as early as 30-60 min after initiating the procedure. No exhaustion in the recruitment was observed in the two groups for at least 5 h during the leukapheresis, and all CD34(+) cell subsets were recruited at a steady rate. However, the collection efficiency in group II was only half of that in group I. In addition, we experienced many technical problems during the leukapheresis in group II. Thus, in 4 out of 7 patients in this group, it was not possible to perform the maximal inlet flow rate because of catheter problems. In conclusion, due to the technical problems associated with the high inlet flow rate procedure and the fact that the relative number of CD34(+) cells harvested and recruited during the leukapheresis was higher in group I than II and, also reflected an approximately two-fold higher collection efficiency, we recommend that LVL be performed by standard inlet flow rate.

Adult↗
PubMed2000

Monoclonal antibodies with neuroblastoma specificity: a flow cytometric analysis of cross-reactivity with CD34+ hematopoietic stem cells.

The aim of this study was to evaluate the specificity of a number of monoclonal antibodies (MAbs) used for immunological in vitro purging of stem cell grafts from neuroblastoma patients. The extent of cross-reactivity of 10 neuroblastoma-specific MAbs (NB-MAb) with CD34+ stem cells from 14 leukapheresis products was analyzed. The level of cross-reactivity was analyzed on a Coulter (Fullerton, CA) flow cytometer using biotinylated NB-MAbs. There was a marked difference in the reactivity of the ten NB-MAbs with CD34+ stem cells. The antibodies could be divided into three groups with increasing levels of cross reactivity. Four antibodies (126-4, 5.1 H11, UJ127.11, and 14.G2a) all reacted with median levels of less than 2% (range 0.0 to 5.4) of CD34+ stem cells (median of 14 patients). Another three antibodies reacted with a median of 3.1-4.1% of the stem cells (UJ13A, Ab390, and Ab459) but with a wide range (0.2 to 25.6). Finally, M340, HSAN 1.2, and antiThy-1 reacted with a median of 9-16% of the stem cells (range 0.6 to 51.5). We conclude that there is a significant variation in the proportion of CD34+ stem cells reacting with each of the ten neuroblastoma antibodies investigated in this study. Therefore, to avoid a significant loss of CD34+ cells from the stem cell product, we find it important to carefully consider which antibodies to use for immunomagnetic purging.

Animals↗
PubMed1999

Linear reduction of clonal cells in stem cell enriched grafts in transplanted multiple myeloma.

In 30 patients with multiple myeloma who were scheduled for peripheral blood stem-cell transplantation, a quantitative analysis of the stem cells following enrichment by anti-CD34 was carried out. To detect the cells of the specific myeloma clone, polymerase chain reaction (PCR) was performed using unique allele-specific oligo primers for the immunoglobulin heavy chain rearrangement. The clonogenic cells before and after stem-cell enrichment, were quantified by a limiting dilution assay and a highly sensitive semi-nested PCR combined with a real-time quantitative PCR. In order to accomplish a statistically adequate end-point analysis, a large number of PCR analyses (40 per sample) were performed. By this technique the lowest detection limit observed was one myeloma cell per 106 cells. Myeloma cells were detected in 29/30 samples from the CD34-enriched fraction. The CD34 selection procedure resulted in a median 28-fold enrichment of CD34+ haemopoietic precursor cells. The stem-cell selection reduced the median concentration of clonal cells per million total cells by half, with a highly significant linear relationship between the number of myeloma cells before and after stem cell enrichment. The median depletion of clonal cells by the overall procedure was 2.15 log units, corresponding to a reduction of the total quantity of clonal cells reinfused into the patients by at least 99.3%. We conclude that CD34+ cell enrichment led to a reliable tumour cell depletion of the order of 2 log, which may not be sufficient since the total number of tumour cells in the leukapheresis product was 7.2 log (median).

Adolescent↗
PubMed1998

BEAM+autologous stem cell transplantation in malignant lymphoma: 100 consecutive transplants in a single centre. Efficacy, toxicity and engraftment in relation to stem-cell source and previous treatment.

One hundred consecutive patients with malignant lymphoma treated with high-dose chemotherapy and autologous stem cell transplantation, followed at least 1 yr post-transplant, are reported, 68 with non-Hodgkin's lymphoma and 32 with Hodgkin's disease. At transplant, 23 patients were in first remission, 69 in later chemosensitive disease and 8 were chemotherapy resistant. Based on previous treatment and stem-cell source, the patients were subdivided into 3 cohorts: BMT1: bone-marrow harvest and transplant after > or =3 treatment regimens (38 patients); BMT2: bone marrow harvest and transplant after less than 3 treatment regimens (24 patients); PBSCT: peripheral-blood stem cell transplant (38 patients, 5 of these with CD34+ cell selected PBSC). The 4-yr survival and progression-free survival of all patients was 45 and 40%, respectively. Forty-one patients have died, 27 of lymphoma, evenly distributed in the cohorts. Fourteen treatment-related deaths occurred, 13 of these in the BMT1 cohort, significantly more than in the other cohorts (p=0.001). In univariate survival analysis cohort, age, disease status at transplant and number of previous treatment regimens were significant. In multivariate survival analysis cohort, age and sex were independently significant, women having a shorter survival. The patients transplanted with unselected PBSC had significantly shorter duration of pancytopenia and hospital stay than the otherwise comparable BMT2 patients, but their progression-free survival was identical. We confirm that high-dose therapy with autologous stem cell transplant from blood or bone marrow in not-too-heavily pretreated patients is a safe procedure but will cure only half the patients.

Adult↗
PubMed1996

[Autologous stem cell transplantation. From bone marrow to selected blood stem cells: 100 consecutive procedures at a single center].

One hundred consecutive autologous stem cell transplants are reported: Non-Hodgkin's lymphoma 51 cases, Hodgkin's disease 27 cases, acute leukaemia 14 cases, multiple myeloma seven cases and chronic myeloid leukaemia one case. Most patients were in their second or later remission. The overall three-year survival for all patients was 60% and the three-year disease-free survival was 50% for lymphoma patients and 30% for acute leukaemia patients. The dominant source of stem cells was bone marrow during 1993, but from 1994 it has been peripheral blood, now totalling 33 cases. There were 12 toxic deaths, all among patients who were heavily treated before bone marrow harvest and transplantation. The patients transplanted with blood stem cells had significantly shorter duration of pancytopenia, and hospital stay, but their disease-free survival was not longer than that of a comparable group of bone marrow transplanted patients. Six patients were transplanted with purified CD34+ cells (selected by avidity column (Ceprate (R)), and had duration of thrombocytopenia and hospital stay similar to the patients transplanted with unmanipulated blood stem cells, but slightly longer duration of neutropenia. We conclude that high-dose therapy with autologous stem cell transplantation in not too heavily pretreated patients is a safe procedure irrespective of the source of stem cells.

Adolescent↗
PubMed1996

Decreased number of CD73 (ecto-5'-nucleotidase) molecules on lymphocytes from patients with primary immunoglobulin deficiencies. Correlation between number of CD73 molecules and T-lymphocyte function in vitro.

CD73 is a bifunctional glycosyl phosphatidylinositol anchored leucocyte differentiation antigen which has specific ecto-5'-nucleotidase (ecto-5'-NT) activity and is an accessory T-lymphocyte activation molecule. The aim of the present study was to investigate the CD73 expression on blood mononuclear cells (BMC) from a group of patients with primary immunoglobulin deficiency (IGD). This group of patients had both significantly decreased levels of ecto-5'-NT on BMC (P = 0.002) and decreased numbers of CD73 molecules per CD73+ lymphocyte (P = 0.01). Five of the 10 patients had a decreased percentage of CD73+ lymphocytes. Among B-lymphocytes the patients had normal percentages of CD73+ cells but four of the 10 patients had numbers of CD73 molecules per CD73+ B-lymphocyte below the normal range. Among CD4-lymphocytes three out of 10 patients had percentages of CD73+ below the normal range and four out of 10 patients had decreased percentages of CD73+ CD8-lymphocytes. Significant correlations were found between in vitro proliferative responses to mitogens and the number of CD73 molecules per CD73+ lymphocyte (rs = 0.60, P < 0.01) and per CD73+ CD8-lymphocyte (rs = 0.64, P < 0.02). In addition, a positive correlation was found between ability to proliferate and level of ecto-5'-NT on BMC (rs = 0.53, P < 0.05). Furthermore the ability of BMC to synthesize ecto-5'-NT was studied. During 2 days culture ecto-5'-NT activity increased markedly on BMC from both patients and healthy donors. The level of activity on BMC from all patients attained levels higher than on freshly isolated BMC from healthy donors. This shows that the decreased levels of ecto-5'-NT found on freshly isolated BMC from patients with IGD is due to defective regulation of the enzyme activity in vivo.

5'-Nucleotidase↗
PubMed1996

No correlation between CD73 expression and ecto-5'-nucleotidase activity on blood mononuclear cells in vitro. Evidence of CD73 (ecto-5'-nucleotidase) on blood mononuclear cells with distinct antigenic properties.

Monoclonal antibodies against ecto-5'-nucleotidase (ecto-5'-NT) have been clustered to CD73. The aim of the present study was to elucidate whether specific ecto-5'-NT activity on blood mononuclear cells (BMC) was correlated with CD73 expression measured by flow cytometry. During culture of CD73-negative lymphocytes the percentage of cells with ecto-5'-NT activity increased without there being a comparable increase in CD73 expression. After 2 days' culture, 9% (3-16, median and range given) demonstrated ecto-5'-NT activity, whereas CD73-positive cells comprised only 1.6% (0.0-3.0). These results show the existence of lymphocytes with ecto-5'-NT activity but without expression of CD73. The ecto-5'-NT activity increased significantly (p<0.02) during culture of unseparated BMC, whereas the number of anti-CD73 binding sites did not change. As a consequence. the number of anti-CD73 binding sites per U ecto-5'-NT activity decreased during culture. Exposure to interleukin-4 or prostaglandin E2 changed the enzymatic activity but not the number of anti-CD73 binding sites. Treatment of BMC with phosphatidylinositol-specific phospholipase-C released 57% (51%-75%) of the ecto-5'-NT activity into the supernatants, without a detectable decrease in CD73 expression. The fact that ecto-5'-NT was removed from the supernatant after precipitation with anti-CD73 showed that the released ecto-5'-NT activity was due to enzymatic activity of CD73 molecules. The results of this study indicate that CD73 exists on BMC in isoforms with distinct capacities to bind mouse monoclonal anti-CD73.

5'-Nucleotidase↗
PubMed1996

Treatment of relapse after allogeneic BMT with donor leukocyte infusions in 16 patients.

Sixteen patients with relapse after allogeneic BMT were treated with donor leukocyte infusions (DLI) from the original donor. The diagnoses at relapse were: CML in chronic phase (CP) (two patients), CML in accelerated phase (AP) (four patients), AML (four patients), MDS (one patient), ALL (four patients) and relapse of Hodgkin's disease (one patient). The patients received a mean of 5.2 x 10(8) leukocytes/kg with a range of 1.4-12.3 x 10(8) leukocytes/kg. Six patients obtained complete remission (CR), one with CML in CP, three with CML in AP, one MDS and one ALL. Partial remission (PR) was seen in three patients, one patient with CML in AP, one with AML and one with Hodgkin's disease. Seven patients had no response (NR) to the infusions, including one patient with CML in CP transplanted with a syngeneic donor. Four patients developed marrow hypoplasia after DLI (three CR and one PR) and two patients (ALL with CR and MDS with CR) were hypoplastic at relapse and marrow hypoplasia continued after DLI. GVHD occurred without GVL, but GVL only occurred in one patient with absence of GVHD. Eleven patients died of leukemia, six patients are alive. Three patients with CML are in CR 12, 12 and 32 months after DLI and one patient with ALL is in CR 15 months after DLI.

Adolescent↗
PubMed1994

In vitro evaluation of a new filter for leucocyte depletion of platelet concentrate during component preparation.

A newly developed filter for prestorage leucocyte depletion of platelet concentrates (PC) was studied. The filter is designed for leucocyte depletion during the preparation of the pool PC from platelet rich buffy coats. In all the leucocyte depleted PC (LD-PC) leucocyte depletion was satisfactory. 19 of 20 units of LD-PC had a leucocyte content below 3 x 10(5) per PC and 1 contained 8 x 10(5) leucocytes. The standard PC contained 2.53 x 10(8) (0.87 x 10(8)-15.3 x 10(8); n = 20) leucocytes per PC (median and range). The quality of the LD-PC was evaluated by measuring platelet activation, platelet morphology, and pre- and poststorage pH. There were no differences in any of the parameters studied.

Blood Platelets↗
PubMed1992

Effects of immunomodulators on ecto-5'-nucleotidase activity on blood mononuclear cells in vitro.

In this study the effects of immunomodulators on the ecto-5'-nucleotidase (ecto-5'-NT) activity on blood mononuclear cells (BMC) were examined in vitro. Interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) decreased the level of ecto-5'-NT activity on BMC whereas prostaglandin E2 (PGE2) increased the ecto-5'-NT level. All three immunomodulators influenced the ecto-5'-NT activity of isolated monocytes whereas only IL-4 and PGE2 had an effect on the enzyme level on isolated lymphocytes. The effect was dependent upon protein synthesis. The effect was dose dependent: IL-4 was effective at concentrations down to 0.5 U/ml, IFN-gamma down to 40 U/ml and PGE2 at nanomolar concentrations. These data indicate that immunomodulators may also take part in the regulation of ecto-5'-NT activity on BMC in vivo. BMC from 7 patients with different immunodeficiency syndromes showed decreased ecto-5'-NT activity on freshly isolated cells. However, following culture ecto-5'-NT activity was increased above the level found on freshly isolated BMC from healthy persons. On BMC from 3 patients with hypogammaglobulinaemia, the effect of IL-4 on the level of ecto-5'-NT activity was identical to that found on BMC from healthy donors, whereas PGE2 increased ecto-5'-NT activity on BMC from only 1 of the 3 patients investigated. The decreased ecto-5'-NT activity of BMC from patients with immunodeficiency may thus be due to a defective regulation of ecto-5'-NT activity in vivo.

5'-Nucleotidase↗
PubMed1991

Complement receptor type 1 (CR1, CD35) expression on peripheral T lymphocytes: both CD4- and CD8-positive cells express CR1.

T lymphocytes from 42 healthy blood donors were examined for expression of CR1 on the cell surface using a fluorescence-activated cell sorter. The fraction of CR1-positive T lymphocytes varied in the range from 1 to 8% (median 2.4%). The CR1-positive T lymphocytes constituted a homogeneous group of cells regarding both size and granulation; they seemed to be larger and more granulated than the average T lymphocytes. The CR1-expressing T lymphocytes were found both in the CD4- and in the CD8-positive subpopulations of T lymphocytes, and although the CD4-positive cells expressed CR1 with a slightly higher percentage than did the CD8-positive cells, this difference was not significant. The number of CR1-positive T lymphocytes did not correlate with the level of CR1 on erythrocytes. The presence of CR1 on a small T lymphocyte population suggests that CR1 on T lymphocytes might play a role in the immune regulation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Lack of immunomodulating effect of disulfiram on HIV positive patients.

Disulfiram (Antabuse (R)) is metabolized to two molecules of diethyldithiocarbamate, which has been reported to be an immunomodulating agent. In a double blind trial, 15 HIV antibody positive homosexual men were given daily doses of 100 mg or 400 mg of disulfiram or placebo, for 4 weeks. All had a CD4-count below 500 X 10(6)/l and/or a pokeweed mitogen response in a lymphocyte proliferation assay less than 50% of normal controls. None suffered from opportunistic infections. No significant effect of disulfiram on immunological, haematological, biochemical or clinical variables was observed in this short-term trial.

Adjuvants, Immunologic↗
PubMed1990

Indomethacin in vitro and in vivo abolishes post-exercise suppression of natural killer cell activity in peripheral blood.

The present study was designed to explain the mechanism of the post-exercise down-regulation of human natural killer (NK) cell activity recently described by us. Fifteen young, healthy volunteers underwent 60 min of bicycle exercise at 75% of maximal oxygen uptake (VO2max). Six of the volunteers were exercised twice with an interval of at least one month. At the second exercise test they received oral indomethacin. Blood samples were collected before and during the last minutes of exercise as well as 2 h and 24 h after work. The NK cell activity (lysis fixed number of mononuclear cells) increased during bicycle exercise, dropped to a minimum 2 h later and returned to pre-exercise levels within 24 h. During bicycle exercise the percentage of NK cells (CD16+ cells) of mononuclear cells increased significantly but returned to normal within 2 h after exercise. Two hours after exercise, however, increased monocyte cell count and neutrophils were found. The in vitro release of prostaglandin E2 from mononuclear cells was increased. Furthermore, the neutrophil chemiluminescence response was also increased in the 2 h post-exercise period; this response is associated with prostaglandin E2 production by neutrophils. Indomethacin, whether administered in vivo or in vitro, fully restored the suppressed post-exercise NK cell activity. Finally, the NK cell activity of monocyte depleted mononuclear cells did not decrease below basal levels after exercise. These findings strongly indicate that prostaglandins released from monocytes and neutrophils are involved in the post-exercise down-regulation of NK cells.

Adult↗
PubMed1989

Natural killer cell activity in peripheral blood of highly trained and untrained persons.

Natural killer (NK) cell activity and concentration of CD16+ cells (NK cells) and CD20+ cells (monocytes) in peripheral blood were measured in highly trained racing cyclists and in age- and sex-matched untrained controls. Median NK cell activity was 38.1% (range 20.0%-57.1%) in trained vs 30.3% (range 19.7%-43.1%) in untrained (P = 0.008). Median %CD16+ cells was 17% (range 7%-33%) in trained vs 11% (3%-29%) in untrained (P = 0.007). Indomethacin in vitro enhanced the NK cell activity in both groups. There was, however, no significant difference between the NK cell activity in trained and untrained after exposure to indomethacin in vitro. Indomethacin-enhanced NK cell activity was 45.9% (range 24.4%-67.5%) in trained and 40.0% (range 23.9%-68.5%) in untrained (P = 0.138). Mean %CD14+ cells was 8.3% (range 2%-15%) in trained vs 3.8% (2%-8%) in untrained (P less than 0.0001). The increased NK cell function thus demonstrated in highly trained persons might result in better resistance against infectious disease.

Adult↗
PubMed1989

Effect of physical exercise on blood mononuclear cell subpopulations and in vitro proliferative responses.

The present study was designed to examine the effect of physical exercise on subsets and proliferative responses of blood mononuclear cells. Sixteen young, healthy volunteers underwent 60 min of bicycle exercise at 75% of maximal oxygen uptake (VO2max). After an interval of at least 1 week, six of the subjects underwent a 60-min back muscle training period at up to 30% of VO2max. Blood samples were collected before and during the last minutes of exercise, as well as 2 and 24 h later. Blood mononuclear cell (BMNC) subpopulations were determined and the proliferative responses after incubation with phytohaemagglutinin (PHA) or purified derivative of tuberculin (PPD), were quantified by [3H]thymidine incorporation. During bicycle exercise the relative blood concentration of T cells (CD3+ cells) declined, mainly due to a fall in T helper cells (CD4+ cells). The natural killer (NK) cell subset (CD16+ cells) increased during work, but reverted after; the monocytes (CD14+ cells) increased 2 h after work, whereas the B-cell subset (CD20+ cells) did not change. BMNC subsets were not significantly changed by back muscle exercise. The PHA-induced proliferative response decreased during bicycle exercise, whereas the PPD-induced response did not change. No significant changes occurred during back muscle exercise. Investigation of subgroups after incubation with [3H]thymidine showed that the proliferative response per CD4+ cell did not change in relation to exercise, but the contribution of the CD4+ subgroup to proliferation declined during bicycle exercise due to the decreased proportion of CD4+ cells. The suppression of the PHA response during bicycle exercise can be explained in part by a relative fall in CD4+ cells. The pool sizes of BMNC subfraction may be elicited by increased catecholamine and cortisol levels.

Adult↗