PubMed Health⌕ Search

Biomedical subjects

E Lizzio

Publications and source records attributed to E Lizzio.

6 recordsLinked to original sources
PubMed1994

Murine splenic hematopoietic subpopulations: the enlarged undifferentiated subset in New Zealand black mice is multipotent stem cells.

We recently reported that a significant population of the murine splenic non-T, non-B "null" cell compartment consists of non-lineage-specific, undifferentiated cells which are in the G0 and G1 phases of the cell cycle and that their numbers are particularly high in the spleens of New Zealand Black mice. A highly enriched population of these non-lineage-specific cells obtained by successive elimination of differentiated cells was further purified to homogeneity by fluorescence-activated cell sorting. The morphologic, phenotypic, and histochemical characteristics of this purified population suggest that these cells may be primitive hematopoietic stem cells. The germ line configuration of the genomic DNA establishes that these are uncommitted stem cells. In vivo, these cells form day 12 colonies in the spleen and liver of lethally irradiated recipients and confer radioprotection. These cells also differentiate into T- and B-cell lineages and reconstitute the immunodeficiency in mice with severe combined immunodeficiency. In response to a combination of a very few early-acting lymphokines and/or stromal cell-conditioned medium in vitro, these cells differentiate into both myeloid and lymphoid cell types. More of these cells are obtained from the enlarged spleens of New Zealand Black mice than from those of BALB/c mice. The presence of a comparatively higher number of stem cells in the spleen than in the marrow or fetal liver provides an alternative, and possibly superior, source of uncommitted stem cells for a variety of experimental investigations or therapeutic manipulations.

Animals↗
PubMed1991

Production of a novel antigen by conjugation of HIV-1 to Brucella abortus: studies of immunogenicity, isotype analysis, T-cell dependency, and syncytia inhibition.

In the present study inactivated human immunodeficiency virus type 1 (HIV-1) was conjugated to Brucella abortus and tested for immunogenicity in normal and anti-L3T4-treated BALB/c mice. HIV-BA was more immunogenic than uncoupled HIV in normal mice, since 6-fold less virus in HIV-BA preparations elicited higher titer responses than HIV-1 alone. Furthermore, the HIV-BA antibody response reached higher levels before the HIV-1 response. Immunoblot analysis showed that most of the HIV-1 antigens were recognized by antibodies induced by either HIV-1 or HIV-BA. Isotype analysis revealed that HIV-1 induced similar levels of IgG1 and IgG2a antibodies, whereas the IgG2a responses to HIV-BA were more pronounced than the IgG1 response. These different IgG subclass patterns suggest that conjugation of HIV-1 to BA changed the immunogenic nature of HIV-1. The requirement for helper T cells was examined by immunizing mice that were depleted of CD4+ T cells by in vivo anti-L3T4 treatment. Under these conditions the IgG responses to HIV-1 were completely eliminated. Although HIV-BA antibody responses were markedly reduced in anti-L3T4-treated mice, anti-HIV-1 antibodies, mainly of the IgG2a isotype, were produced. The antibodies generated by HIV-1 and HIV-BA immunization were also tested for their ability to inhibit syncytia formed by infecting CD4 + CEM cells with gp160 vaccinia. Sera from normal mice, immunized with either HIV-1 or HIV-BA were capable of inhibiting syncytia. In contrast, following anti-L3T4 treatment, only mice immunized with HIV-BA, but not HIV-1, produced antibodies capable of inhibiting syncytia.

Animals↗
PubMed1980

Variable expression of delayed hypersensitivity in different mouse strains using dimethyl dioctadecyl ammonium bromide as an adjuvant.

Delayed-type hypersensitivity measured as footpad swelling was studied in large number of inbred mouse strains. A conjugate of bovine serum albumin (BSA) with the small 2,4-dinitrophenyl (DNP) hapten served to generate strong reactions, specific for the DNP group. Delayed hypersensitivity was produced with the DNP-BSA complex mixed with the cationic, surface active lipid, dimethyl dioctadecyl ammonium bromide (DDA). Great variation was observed in delayed hypersensitivity among different mouse strains. For convenience, the mice were classified into five groups, notably: non-, low, moderate, good and high responders. The highest responding animals were BALB/cJ mice, the lowest were P/JN and outbred nu/nu mice. No correlation was observed between H-2 type and the intensity of the elicited reactions.

Adjuvants, Immunologic↗
PubMed1977

Increased spontaneous activity of antibody-forming cells in the peripheral blood of patients with active SLE.

Thirty-seven patients with criteria for systemic lupus erythematosus (SLE) and 18 normal controls were studied for their spontaneous background IgM antibody plaque-forming clell number to specific chemical haptens. Active SLE patients had significantly more plaque-forming cells in their peripheral blood to a total of five chemical determinants than did patients with inactive disease or controls. This increased number of plaque forming-cells correlated with depressed serum C3 levels by Spearman rank-order analysis. The finding of elevated numberof spontaneous IgM plaque-forming cells to defined chemical haptens supports the concept that active SLE demonstrates a generalized increase in B-cell activity toward a variety of antigens.

Adult↗
PubMedDate not supplied

Use of a quantitative product-enhanced reverse transcriptase assay to monitor retrovirus levels in mAb cell-culture and downstream processing.

Murine hybridoma cells used in the production of monoclonal antibodies (mAb's) produce endogenous type C retrovirus particles. Regulatory agencies require a demonstration that mAb's intended for human use are free of retrovirus with an adequate margin of safety. This is usually achieved by validation studies, performed at small scale, to demonstrate that the manufacturing process is capable of removing or inactivating several different model viruses, including a murine retrovirus. In this report, we assess the utility of the TaqMan fluorogenic 5'-nuclease Product-Enhanced Reverse Transcriptase (TM-PERT) assay for measuring reverse transcriptase (RT) activity in cell-culture samples and RT removal by models of processing steps. The levels of RT activity contained in laboratory-scale cell-culture harvests (10(8)-10(13) pU/mL) were substantially above the detection limit of the TM-PERT assay ( approximately 10(6) pU/mL). The nature of the RT activity from cell culture was complex, but the bulk of RT activity in clarified mAb harvests appears to be contained in large molecular weight viral particles. In laboratory-scale chromatographic runs, sufficient RT activity was present in mAb-containing eluates to accurately calculate its log(10) reduction value (LRV), typically between 2 and 4 log(10) per step. Monoclonal antibody purified using a model purification scheme consisting of three serial columns contained some residual RT activity near the limit of detection. The data indicate that the TM-PERT assay, because it is quantitative and highly sensitive and can be used to analyze a large number of samples in a short period, is ideally suited to investigate and optimize retrovirus clearance in purification processes.

Animals↗