Development of a sensitive, specific reverse transcriptase polymerase chain reaction-based assay for epithelial tumour cells in effusions.
(1/638)
We developed a sensitive and specific method for the detection of epithelial cancer cells in effusions with a two-stage molecular-based assay which combined enrichment for cancer cells by immunomagnetic bead selection and reverse transcriptase polymerase chain reaction (RT-PCR) detection of epithelial glycoprotein 2 (EGP-2) RNA. Preliminary experiments indicated that immunobead selection was essential to avoid occasional false-positive RT-PCR results, and this method detected ten breast cancer cells electively added to 10(7) cytologically negative effusion cells. We studied 110 cases of pleural (n = 68) and peritoneal (n = 42) effusions (30 from patients with known carcinoma and 80 from those without known carcinoma), and the results were compared with cytological findings. Of 18 effusions that were cytologically positive or suspicious for malignant cells, 17 (94%) were positive for EGP-2 RNA (the one negative sample was from a patient who recently received combination chemotherapy). Of 92 cytologically negative samples, 11 (12%) were positive for EGP-2, including six patients with a history of previous or current carcinoma. Our method appears to be highly specific and increases the sensitivity of detection of malignant cells; it may be a useful adjunct to routine cytopathological examination. (+info)
Immunochemical detection and isolation of DNA from metabolically active bacteria.
(2/638)
Most techniques used to assay the growth of microbes in natural communities provide no information on the relationship between microbial productivity and community structure. To identify actively growing bacteria, we adapted a technique from immunocytochemistry to detect and selectively isolate DNA from bacteria incorporating bromodeoxyuridine (BrdU), a thymidine analog. In addition, we developed an immunocytochemical protocol to visualize BrdU-labeled microbial cells. Cultured bacteria and natural populations of aquatic bacterioplankton were pulse-labeled with exogenously supplied BrdU. Incorporation of BrdU into microbial DNA was demonstrated in DNA dot blots probed with anti-BrdU monoclonal antibodies and either peroxidase- or Texas red-conjugated secondary antibodies. BrdU-containing DNA was physically separated from unlabeled DNA by using antibody-coated paramagnetic beads, and the identities of bacteria contributing to both purified, BrdU-containing fractions and unfractionated, starting-material DNAs were determined by length heterogeneity PCR (LH-PCR) analysis. BrdU-containing DNA purified from a mixture of DNAs from labeled and unlabeled cultures showed >90-fold enrichment for the labeled bacterial taxon. The LH-PCR profile for BrdU-containing DNA from a labeled, natural microbial community differed from the profile for the community as a whole, demonstrating that BrdU was incorporated by a taxonomic subset of the community. Immunocytochemical detection of cells with BrdU-labeled DNA was accomplished by in situ probing with anti-BrdU monoclonal antibodies and Texas red-labeled secondary antibodies. Using this suite of techniques, microbial cells incorporating BrdU into their newly synthesized DNA can be quantified and the identities of these actively growing cells can be compared to the composition of the microbial community as a whole. Since not all strains tested could incorporate BrdU, these methods may be most useful when used to gain an understanding of the activities of specific species in the context of their microbial community. (+info)
Identification of cord blood dendritic cells as an immature CD11c- population.
(3/638)
Dendritic cells (DC) are the main stimulators of primary T-cell responses and, thus, probably play a role in the immune reactions after stem cell transplantation. Very little is known about DC in cord blood (CB) and about their potential involvement in the low incidence and severity of acute graft-versus-host disease after CB transplantation. Here, CBDC were identified as a HLA-DR+ cell population, lacking the CD3, CD11b, CD14, CD16, CD19, CD34, CD56, and glycophorin A lineage markers (lin). This lin-/HLA-DR+ population represented 0.3% +/- 0.1% (mean +/- SD; range, 0.1% to 0. 6%; n = 15) of CB mononuclear cells, and CB contained 5.4 +/- 3.2 x 10(3) CBDC/mL (1.8 to 13.0 x 10(3); n = 15). CBDC expressed CD4, CD11a, CD18, CD45RA, CD50, CD54, and CD123, but showed no expression of CD1a, CD11c, CD33, CD40, CD45R0, CD80, CD83, and CD86 and only limited expression of CD58, CD102, and CD116. Despite this immature phenotype, immunomagnetically lin--enriched CBDC were potent stimulators of allogeneic CB T cells. As few as 266 +/- 107 (193 to 530; n = 10) lin-/HLA-DR+ CBDC stimulated a significant response. However, CBDC failed to take up protein or peptide antigens. Thus, in CB there is a prevalence of a DC subpopulation, resembling the CD11c- DC identified in tonsils, the so-called plasmacytoid T cells, which may exert a function distinct from the CD11c+ DC subpopulation. (+info)
Prevention of graft-versus-host disease in high risk patients by depletion of CD4+ and reduction of CD8+ lymphocytes in the marrow graft.
(4/638)
From March 1994 to September 1997, 30 patients with hematological malignancies (12 ANLL, 10 CML, four ALL and four multiple myeloma) received HLA-identical allogeneic bone marrow transplants with the marrow graft selectively depleted of CD4+ lymphocytes and the CD8+ cell content adjusted to 1x10(6)/kg. Total depletion of CD4+ and partial depletion of CD8+ lymphocytes was carried out by an immunomagnetical method. All patients were considered as having high risk for developing GVHD by at least one of the following criteria: patient age >35 years; donor age >35 years; donor multiparity or marrow from an unrelated donor. Twenty-four cases received marrow from an identical sibling and six from an unrelated donor. In order to assess the role of methotrexate (MTX) in addition to cyclosporin A (CsA) after transplant, patients were randomly assigned to received either CsA alone (n = 15) or CsA plus a short course of MTX (n = 15). No case of primary graft failure was observed, but two patients developed late graft failure. Six patients presented grade II acute GVHD and no case of severe III-IV GVHD was seen. The actuarial probability of developing grade II-IV acute GVHD was 25.9+/-9.6% for the entire population. Patients receiving post-transplant CsA + MTX had significantly less probability of acute GVHD than those receiving CsA exclusively (6.7+/-6.4% vs. 50.5+/-17.8%, P = 0.03) and the schedule of post-transplant immunosuppression was the only factor associated with the incidence of acute GVHD in a multivariate analysis. The actuarial incidence of chronic GVHD for the entire population was 31.8+/-12.5, and there was no significant difference between both groups with additional prophylaxis. Four patients with CML and three with ANLL relapsed: the actuarial probability of remaining in complete remission for all patients was 53.6+/-17.3%. For patients with acute leukemia, the probability of remaining in complete remission did not differ significantly between those transplanted in first complete remission and those receiving a transplant in more advanced phases of the disease (87.5+/-11.6% vs. 72.9+/-16.5%; P = 0.44). The incidence of mixed chimerism assessed by PCR was 34%. Nineteen patients are alive between 2 and 43 months post-transplant, the probability of overall survival being 57.8+/-10.4%. Our data indicate that this method of selective T cell depletion is very effective in preventing acute GVHD in high risk patients, particularly when used in combination with post-transplant CsA + MTX. (+info)
Development and characterization of a fluorescent-bacteriophage assay for detection of Escherichia coli O157:H7.
(5/638)
In this paper we describe evaluation and characterization of a novel assay that combines immunomagnetic separation and a fluorescently stained bacteriophage for detection of Escherichia coli O157:H7 in broth. When it was combined with flow cytometry, the fluorescent-bacteriophage assay (FBA) was capable of detecting 10(4) cells/ml. A modified direct epifluorescent-filter technique (DEFT) was employed in an attempt to estimate bacterial concentrations. Using regression analysis, we calculated that the lower detection limit was between 10(2) and 10(3) cells/ml; however, the modified DEFT was found to be an unreliable method for determining bacterial concentrations. The results of this study show that the FBA, when combined with flow cytometry, is a sensitive technique for presumptive detection of E. coli O157:H7 in broth cultures. (+info)
Immunomagnetic bone marrow (BM) and peripheral blood progenitor cell (PBPC) purging in follicular lymphoma (FL).
(6/638)
Twenty-nine B cell follicular lymphoma (FL) patients had their BM (n = 12) or PBPC (n = 17) purged using a panel of monoclonal antibodies and immunomagnetic beads (IMB). The median recovery of nucleated cells (NC) and CD34+ cells was 59.3% (40.5-74) and 56.1% (30.8-82.9) in BM and 77.2% (64.7-88.3) and 73.5% (61.5-98.6) in PBPC (P<0.0005). A median of >1.62 and >1.02 log of target cell depletion was achieved as judged by flow cytometry analysis in BM and PBPC, respectively. Of 29% of initial harvests that had a bcl2 PCR-amplified signal, 37.5% became PCR negative in the final purged products. Absorbed cells containing IMB-target cell complexes gave bcl2 rearrangement signal in 20% of samples in which the start and final purged components were negative. Twenty-three of 26 patients receiving an autologous purged product are evaluable for engraftment. Median time to reach an ANC >0.5x10(9)/l and platelet count >20x10(9)/l was 21 (11-43) and 41 days (13-70) for BM (n = 9) and 14 (10-31) and 14 (8-37) for PBPC (n = 14) autografted patients (P = 0.01 and 0.001). One patient did not engraft and was rescued with a back-up BM. These data demonstrate that this indirect immunomagnetic technique is able to achieve a high grade of lymphoma cell depletion in BM and PBPC and that these purged products are capable of rapid engraftment after autologous transplantation. (+info)
Sensitive detection of Escherichia coli O157:H7 in food and water by immunomagnetic separation and solid-phase laser cytometry.
(7/638)
Rapid, direct methods are needed to assess active bacterial populations in water and foods. Our objective was to determine the efficiency of bacterial detection by immunomagnetic separation (IMS) and the compatibility of IMS with cyanoditolyl tetrazolium chloride (CTC) incubation to determine respiratory activity, using the pathogen Escherichia coli O157:H7. Counterstaining with a specific fluorescein-conjugated anti-O157 antibody (FAb) following CTC incubation was used to allow confirmation and visualization of bacteria by epifluorescence microscopy. Broth-grown E. coli O157:H7 was used to inoculate fresh ground beef (<17% fat), sterile 0.1% peptone, or water. Inoculated meat was diluted and homogenized in a stomacher and then incubated with paramagnetic beads coated with anti-O157 specific antibody. After IMS, cells with magnetic beads attached were stained with CTC and then an anti-O157 antibody-fluorescein isothiocyanate conjugate and filtered for microscopic enumeration or solid-phase laser cytometry. Enumeration by laser scanning permitted detection of ca. 10 CFU/g of ground beef or <10 CFU/ml of liquid sample. With inoculated meat, the regression results for log-transformed respiring FAb-positive counts of cells recovered on beads versus sorbitol-negative plate counts in the inoculum were as follows: intercept = 1.06, slope = 0.89, and r2 = 0. 95 (n = 13). The corresponding results for inoculated peptone were as follows: intercept = 0.67, slope = 0.88, and r2 = 0.98 (n = 24). Recovery of target bacteria on beads by the IMS-CTC-FAb method, compared with recovery by sorbitol MacConkey agar plating, yielded greater numbers (beef, 6.0 times; peptone, 3.0 times; water, 2.4 times). Thus, within 5 to 7 h, the IMS-CTC-FAb method detected greater numbers of E. coli O157 cells than were detected by plating. The results show that the IMS-CTC-FAb technique with enumeration by either fluorescence microscopy or solid-phase laser scanning cytometry gave results that compared favorably with plating following IMS. (+info)
Improvement of tumor cell depletion by combining immunomagnetic positive selection of CD34-positive hematopoietic stem cells and negative selection (purging) of tumor cells.
(8/638)
One possible reason for relapse after high-dose chemotherapy is retransplantation of tumor cells contaminating autologous hematopoietic stem cell transplants. Residual tumor cells can be diminished by various purging methods. We studied tumor cell depletion by sequentially combining immunomagnetic positive selection of CD34+ hematopoietic stem cells using Isolex50 or Isolex300SA and negative tumor cell depletion using MACS, MaxSep or Isolex50 systems. Using these separation systems in different selection sequences, i.e. positive followed by negative selection (+/- selection) or vice versa, four groups of double selections (Isolex50/MACS, Isolex50/MaxSep, MaxSep/Isolex50, Isolex300SA/Isolex50) were studied. Testing these double-purging procedures mean additional tumor cell depletion (deltaTCD) achieved by the second selection step ranged from 1.1+/-0.58 log (n = 5, +/- Isolex50/MACS) to 2.0+/-1.1 log (n = 7, -/+ MaxSep/Isolex50). Loss of CD34+ cells during double selection sometimes was extensive and mean yield of CD34+ cells ranged from 12.8+/-11.5% (n = 6, +/- Isolex50/MaxSep) to 43.2% (n = 2, +/- Isolex300SA/Isolex50). Calculated values for mean yield-corrected deltaTCD ranged from 0.64+/-0.3 log (n = 5, +/- Isolex50/MACS) to 1.4+/-1.3 log (n = 7, -/+ MaxSep/Isolex50). During positive selection of -/+ selection (MaxSep/Isolex50) relative tumor cell enrichment was detectable leading to an increment of mean tumor cell contamination rate. Best results for total TCD were achieved by the combination of Isolex50/MaxSep (n = 6; TCD: 4.2 log; yield CD34+: 12.8%) and Isolex300/Isolex50 (n = 2; TCD: 3.8 log; yield CD34+: 43.2%). Furthermore, we have established and tested a new simultaneous +/- selection method by using CD34-specific releasing agent PR34+ in the Isolex300i. With this method we have obtained a mean total yield-corrected TCD of 4.7 log (n = 4; range: 4.1-6.0 log) with high CD34+ cell yield (mean: 69.8%) and CD34+ cell purity (mean: 92.8%). Since this new simultaneous +/- purging procedure is safe, applicable within a closed system (GMP-like) and most effective, we recommend it for further testing in a clinical setting. (+info)