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Biomedical subjects

B Amill

Publications and source records attributed to B Amill.

24 records · Page 2Linked to original sources
PubMed1993

Differential effect of cryopreservation on natural killer cell and lymphokine-activated killer cell activities.

The use of lymphokine-activated killer (LAK) cell therapy in delayed treatment requires the use of cryopreserved effector cells. The purpose of this study was to determine the optimal cryopreservation protocol for the maintenance of cytotoxic activity in mononuclear cells (MNCs). MNCs were cryopreserved with dimethyl sulfoxide or 1,2-propanediol before and after 3 days of culture with recombinant interleukin 2. The effects of cryopreservation on cell recovery, LAK cell and natural killer (NK) cell cytotoxic activities, and surface antigen markers were studied. Recovery of nonactivated MNCs was higher with 1,2-propanediol than with dimethyl sulfoxide (p < 0.05). Cytotoxic activities, measured with a 51Cr release assay, significantly decreased after thawing, on both activated cells (76.3%; range, 35.8-92.2%) and fresh cells (54.6%; range, 17.5-75.4%). A 6-day kinetic test was used to compare the cytotoxic activity of cryopreserved and fresh cells. The results showed different patterns for NK cells (cryopreserved cells had lower levels of activity than fresh cells) and LAK cells (cryopreserved cells had higher levels of activity than fresh cells). Phenotype changes of effector cells in culture, with and without cryopreservation, were monitored by flow cytometry using monoclonal antibodies. These results were compared with changes in the cytotoxicity of cells with and without cryopreservation. After thawing, there was a decrease in MNCs expressing CD14 and CD56. Recovery of the CD56 marker correlates with increased cytotoxic activity. Despite some loss of NK cell activity, it is concluded that MNCs may be successfully cryopreserved before their use in immunotherapeutic treatment.

CD4-CD8 Ratio↗
PubMed1990

Activated T-lymphocytes in newly diagnosed type I diabetic patients: relationship to residual beta cell function.

The relationship between T-lymphocyte activation and residual beta-cell function was studied in 19 newly diagnosed Type I (insulin dependent) diabetic patients, aged 6-43 years, 7-10 days after beginning insulin therapy and once normoglycemia had been achieved. Residual beta-cell function was studied by measurement of plasma C-peptide concentration 6 minutes after intravenous glucagon administration. T-lymphocyte activation markers, HLA-DR/CD3 and interleukin-2 receptor (Tac) expression, were measured in peripheral blood mononuclear cells by dual- or single-colour flow cytometry. Six patients showed increased percentages of activated T lymphocytes (increased HLA-DR positivity in four patients, and an excess of Tac-positive cells in two). The mean percentage of activated T lymphocytes was higher in patients with stimulated C-peptide levels below 300 pmol/l (8.32 +/- 1.32%) than in those with plasma stimulated C-peptide above 300 pmol/l (3.93 +/- 0.49%), P less than 0.01, or controls (3.48 +/- 0.60%), P less than 0.01. Furthermore, the six patients with increased percentages of activated T lymphocytes were in the low stimulated C-peptide group. A negative correlation was found between the percentage of activated T lymphocytes and glucagon-stimulated C-peptide (r = -0.5877, P less than 0.01). We conclude that increased T-lymphocyte activation is associated with a higher impairment of beta-cell function at the onset of Type I diabetes mellitus.

Adolescent↗
PubMedDate not supplied

Peripheral blood CD34+ cell immunomagnetic selection in breast cancer patients: effect on hematopoietic progenitor content and hematologic recovery after high-dose chemotherapy and autotransplantation.

BACKGROUND: Tumor cells have been detected in mobilized peripheral blood of breast cancer patients, and they may contribute to tumor recurrence after the transplantation of peripheral blood progenitor cells. One of the most widespread technologies for tumor purging of the graft is immunomagnetic hematopoietic progenitor cell selection. STUDY DESIGN AND METHODS: The study assessed the effectiveness of a magnetic cell-separation system in selecting functional subpopulations of hematopoietic progenitors from 14 blood-derived harvests of 11 patients with high-risk breast cancer after mobilization following cytotoxic chemotherapy supported by granulocyte--colony-stimulating factor, as well as the feasibility of transplanting these selected subpopulations. RESULTS: CD34(+)-enriched cell fractions had a median purity of 93.0 percent (72.7-98.5%). The procedure yielded 52.6 percent of the CD34+ cell input (39.4-116.8%). Median recoveries of colony-forming units (CFUs) (36.87%) and cobblestone area-forming cells (CAFCs) (152.5%) were, respectively, 0.70 and 2.87 times those of CD34+ cells (52.6%). Moreover, CAFC efficiency in the positive cell fraction was 2.57 times that in the starting cell fraction. Peripheral blood neutrophil counts of 0.5 x 10(9) per L and platelet counts of 20 x 10(9) per L were reached after median times of 9 and 11 days, respectively. The number of transfused CAFCs per kg, CD34+ cells per kg, and postthaw CFU-granulocyte-macrophage per kg was correlated, respectively, with the speed of engraftment of neutrophils, platelets, or both. Tumor cells detected in one patient's peripheral blood were not found after CD34+ cell selection. CONCLUSION: Transplantation of immunomagnetically purified peripheral blood CD34+ cells does not increase transplantation-related morbidity. It induces a selective enrichment of more immature hematopoietic progenitors, which makes it suitable for use in cell expansion and gene therapy protocols.

Adult↗