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Biomedical subjects

H Levine

Publications and source records attributed to H Levine.

At least 55 records · Page 3Linked to original sources
PubMed1996

Sperm transport and survival post-application of a new spermicide contraceptive. Advantage 24 Study Group.

The present study was undertaken to evaluate the effectiveness of Advantage 24 to inhibit sperm transport and survival when applied at 24 hours, 12 hours, and 15-30 minutes prior to a single act of intercourse. Conceptrol, applied at 15-30 minutes before intercourse, was employed as the comparative spermicide. One-hundred-thirty-nine women, aged 22 to 45 years, were enrolled into the study and 111 completed the trial. The ability of the spermicides to immobilize sperm was assessed by postcoital testing (PCT) and by examining the proportion of sperm immobilization failure (SIF) rates. SIF was a postcoital test result with > or = 10 sperm with progressive motility (either sluggish or rapid) per x 400 power field. Conceptrol and Advantage 24 used at 15-30 minutes were similar with respect to their ability to inactivate sperm (0% and 2% SIF, respectively, p = 0.5). At longer intervals between spermicidal application and intercourse, less inhibition of sperm motility was noted (9% and 14% SIF for 12 and 24 hours, respectively). The present study indicates that Advantage 24 is an effective agent to immobilize sperm. The action of Advantage 24 may decrease if it is applied earlier than 15-30 minutes before intercourse.

Administration, Intravaginal↗
PubMed1995

Functional consequences of APO-1/Fas (CD95) antigen expression by normal and neoplastic hematopoietic cells.

Murine monoclonal antibody (mAb) 7C11 binds to the same cell surface epitope as anti-APO-1 and anti-Fas and reacts specifically with cells transfected with a cDNA encoding the human Fas antigen. Furthermore, incubation with 7C11 causes death of hematopoietic cell lines that express APO-1/Fas but not APO-1/Fas-negative cell lines. 7C11 therefore recognizes the human APO-1/Fas (CD95) antigen, a 40 to 50 kDa cell surface glycoprotein that can trigger apoptosis or programmed cell death. Expression of APO-1/Fas antigen by normal and neoplastic hematopoietic cells was determined by flow cytometry using 7C11. APO-1/Fas is expressed by approximately 30 to 40% of resting peripheral blood T cells, B cells, and monocytes and by approximately 5% of resting NK cells and thymocytes. It was not detected on granulocytes, erythrocytes, or platelets. Approximately 80 to 90% of activated T cells, B cells, and thymocytes express APO-1/Fas, as do the majority of activated NK cells. Perturbation of APO-1/Fas by 7C11 does not affect the viability of resting lymphocytes or monocytes. In contrast, activated T cells and NK cells undergo apoptosis within 3 hours of exposure to 7C11. Other mAb that stimulate T cells or NK cells do not cause rapid induction of programmed cell death. APO-1/Fas antigen is expressed by many cell lines of lymphoid and myeloid lineage. However, this antigen was detected on neoplastic cells from only one of 69 patients with acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, chronic lymphocytic leukemia, or multiple myeloma. Only 3 out of 25 tumor samples from patients with non-Hodgkin's lymphoma were found to express APO-1/Fas. All three of these lymphomas harbored the bcl-2-Ig fusion gene associated with the chromosomal translocation t (14;18). Conversely, only 27% of lymphomas that possessed the bcl-2-Ig gene were found to express the APO-1/Fas antigen. Like normal activated lymphocytes, leukemia and lymphoma cells that expressed APO-1/Fas antigen were found to undergo apoptosis in vitro after incubation with 7C11. The APO-1/Fas antigen appears to regulate the growth of normal hematopoietic cells, and the marked upregulation of this antigen on activated normal lymphocytes contrasts sharply with the absence of APO-1/Fas on neoplastic cells of hematopoietic lineage. Defects in the apoptotic signal delivered through this antigen might contribute to the pathogenesis of hematopoietic neoplasms. Thus, the gene encoding APO-1/Fas can be considered a novel type of tumor suppressor gene, just as bcl-2 can be considered a cellular proto-oncogene.

Animals↗
PubMed1994

Regulation of the 28 kDa heat shock protein by retinoic acid during differentiation of human leukemic HL-60 cells.

Dysregulation of hematopoietic cellular differentiation contributes to leukemogenesis. Unfortunately, relatively little is known about how cell differentiation is regulated. Considering that heat shock proteins (hsp) and specifically the small hsps have been increasingly linked to growth regulation, we sought to determine whether the mammalian small hsp (hsp28) is a growth-regulatory candidate during hematopoietic cell differentiation. Because of its effects on cell growth and differentiation and its increasing clinical use as a differentiating agent, we examined the effect of retinoic acid (RA) on hsp28 during differentiation of the human leukemic HL-60 cell line. Although hsp28 was constitutively expressed at low levels in untreated HL-60 cells, steady state hsp28 protein increased transiently, concomitant with the onset of G1 cell cycle arrest. Furthermore, hsp28 phosphorylation transiently increased within one hour following treatment with RA. Interestingly, in contrast to other differentiating agents the induction of hsp28 by RA was post-transcriptionally mediated with hsp28 protein and mRNA being discordantly regulated. These observations underscore the complex regulation of hsp28 by RA during granulocytic differentiation of human leukemic cells and indicate hsp28 as an intermediary in the pathway through which retinoids exert their growth and differentiative effects.

Cell Cycle↗
PubMed1993

Fc gamma RIIIA-mediated signaling involves src-family lck in human natural killer cells.

The cell surface receptor for IgG Fc domain (Fc gamma RIIIA, CD16) is present as a multimeric complex on human NK cells and is essential for antibody-dependent cellular cytotoxicity. Although CD16 engagement induces tyrosine phosphorylation of several substrates, the intracytoplasmic domains of the CD16 molecule lack intrinsic protein tyrosine kinase consensus sequences. We report here that, in human NK cells, engagement of the CD16 receptor induces tyrosine phosphorylation of p56lck tyrosine kinase. CD16 triggering through anti-receptor antibody enhances in vitro kinase activity of phosphotyrosyl proteins and autophosphorylation activity of anti-lck immunoprecipitates. Similar results were obtained after stimulation with IL-12. In vivo labeling experiments showed that CD16 cross-linking primarily induces in vivo phosphorylation of p56lck at the tyr-394 autophosphorylation site. Using in vitro kinase assay of CD16 immunoprecipitates from lysates of human NK cells, we demonstrated that a phosphorylated protein of 62 to 65 kDa was co-precipitated with CD16. Reprecipitation experiments also suggested that a small amount of p56lck may interact with this complex. These results indicate that CD16 triggering involves p56lck and that this kinase is therefore involved in the signaling pathways regulating NK cell cytolytic functions. However, additional kinases not yet identified are also likely to play a role in the early signaling events through CD16.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1993

Developmental regulation of a mucinlike glycoprotein selectively expressed on natural killer cells.

Natural killer (NK) cells are CD3:TCR-, CD16+, CD56+ large granular lymphocytes capable of recognizing and eliminating a variety of virus-infected, malignant, and antibody-coated target cells. Two functionally distinct populations of peripheral blood NK cells can be differentiated by their surface expression of an isoform of the neural cell adhesion molecule (CD56). CD56bright NK cells have the attributes of an undifferentiated cell, in that they proliferate in response to exogenous cytokines, but exert poor cytolytic activity. CD56dim NK cells have the attributes of a more differentiated cell, in that they proliferate poorly in response to exogenous cytokines, but are potent cytolytic effector cells. Here we describe the molecular characterization of a NK cell restricted epitope (PEN5) that is selectively expressed on the functionally differentiated CD56dim NK cells. PEN5+ NK cells proliferate poorly in response to interleukin 2 (IL-2), but are potent cytolytic effectors, whereas PEN5- NK cells proliferate in response to IL-2, but are poor cytolytic effectors. Biochemical and immunochemical analyses reveal the PEN5 epitope to be an unusual sulfated poly-N-lactosamine carbohydrate related to keratan sulfate glycosaminoglycans. Immunoprecipitates prepared using a monoclonal antibody reactive with PEN5 include two polydisperse membrane-bound glycoproteins, PEN5 alpha (120-170 kD) and PEN5 beta (210-245 kD). Enzymatic deglycosylation reduces the apparent molecular weight of both PEN5 isoforms by 80-90%, and classifies PEN5 beta as a mucinlike glycoprotein. The surface expression of the PEN5 epitope is downmodulated by stimuli that induce NK cell proliferation, and it is absent from leukemic NK cells of patients with granular lymphocyte proliferative disorder. Taken together, these results indicate that PEN5 is a developmentally regulated poly-N-lactosamine epitope associated with a mucin-type glycoprotein, whose expression is restricted to the population of nonproliferative NK cells fully committed to cytolytic effector function.

Amino Sugars↗
PubMed1993

Prediction of graft-versus-host disease by phenotypic analysis of early immune reconstitution after CD6-depleted allogeneic bone marrow transplantation.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality following allogeneic bone marrow transplantation (BMT). Because GVHD is frequently refractory to treatment, the early identification of high-risk patients could have significant clinical value. To identify such patients, we examined early immunologic recovery in 136 patients with hematologic malignancies who received anti-T12 (CD6)-purged allogeneic bone marrow over a 9-year period. The majority of patients received marrow from HLA-matched sibling donors after ablation with cyclophosphamide and total body irradiation. No patients received any immune suppressive medications for GVHD prophylaxis. The fraction and absolute numbers of peripheral blood lymphocytes (PBL) expressing the CD3, CD4, CD8, and CD56 surface antigens were determined weekly by immunofluorescence analysis in patients beginning 8 to 14 days (week 2) after marrow infusion. Results in patients who did or did not subsequently develop GVHD post-BMT were compared. Within 2 weeks of marrow infusion, patients who developed grades 2-4 GVHD had significantly higher percentages and absolute numbers of CD8+ T cells and a lower fraction of CD56+ natural killer (NK) cells than individuals who remained free of GVHD. Thirty-five percent of patients whose PBL were greater than 25% CD8+ in the second posttransplant week developed GVHD, compared with only 3% of patients who had < or = 25% CD8+ cells (odds ratio 37.8; 95% confidence interval [CI] 4.1 to 397). A subgroup of patients at very high risk for GVHD could be identified based on the combined frequency of CD8+ T cells and NK cells in blood. Seventy-five percent of patients with greater than 25% CD8+ cells and < or = 45% CD56+ cells during week 2 post-BMT developed GVHD, compared with only 11% of the remaining patients (odds ratio 24.9; 95% CI, 5.3 to 117.0). None of the 23 patients with both less than 25% CD8+ cells and greater than 45% CD56+ cells in the second posttransplant week developed grades 2-4 GVHD. Our findings indicate that CD8+ T cells play an important role in the pathogenesis of GVHD in humans. Analysis of immune reconstitution early after BMT is useful in predicting the onset of GVHD and can help direct the implementation of treatment strategies before the appearance of clinical manifestations. Such interventions may decrease the morbidity and mortality associated with allogeneic BMT and ultimately improve overall survival.

Adult↗
PubMed1993

Costimulatory signals are required for optimal proliferation of human natural killer cells.

CD56dim NK cells, which comprise approximately 90% of human peripheral blood NK cells, respond to IL-2 with cytokine production, up-regulation of functionally relevant surface molecules, and augmented cytolytic activity. Nevertheless, CD56dim NK cells proliferate poorly in response to IL-2 alone. We found that other NK cell mitogens, including IL-4, IL-7, and IL-12, also induced little proliferation of CD56dim NK cells. Indeed, IL-2 stimulated at least 10-fold more NK cell proliferation than did IL-4, IL-7, or IL-12. In contrast, leukocyte-conditioned medium (LCM) induced two- to threefold greater proliferation of CD56dim NK cells than did optimal concentrations of IL-2. Although the calcium ionophore ionomycin did not stimulate proliferation by itself, it markedly augmented LCM-induced proliferation of CD56dim NK cells. Proliferation in response to either LCM alone or LCM together with ionomycin was almost completely abrogated by anti-IL-2R antibodies. Thus, IL-2 appears to be necessary but not sufficient for optimal proliferation of CD56dim NK cells. LCM-induced proliferation of ionomycin-activated CD56dim NK cells was inhibited 24% by anti-IL-1 heteroantisera and 57% by anti-TNF antisera; a combination of both antisera inhibited proliferation by 73%. Furthermore, although rIL-1 and TNF did not induce proliferation by themselves, both cytokines could augment IL-2-induced proliferation of resting or ionomycin-activated NK cells. Hence IL-1 and TNF do not appear to be primary NK cell mitogens, but rather accessory factors that can enhance IL-2-dependent NK cell proliferation. Stimulation through CD2 or CD16 Ag did not enhance LCM-induced NK cell proliferation. However, stimulation with NK-sensitive K562 cells strongly augmented CD56dim NK cell proliferation to LCM or to IL-2, IL-1, and TNF in combination. NK-resistant Daudi cells did not promote the proliferation of highly purified NK cells. Thus, NK cell proliferation may be enhanced by triggering through putative receptors for natural killing, and ionomycin may mimic such triggering. Although IL-2 by itself can induce NK cell proliferation, most NK cells resemble T and B lymphocytes in that they require multiple signals for optimal proliferation.

Animals↗
PubMed1993

Association of a 70-kDa tyrosine phosphoprotein with the CD16: zeta: gamma complex expressed in human natural killer cells.

The CD16: zeta: gamma receptor complex allows natural killer (NK) cells to recognize and eliminate antibody-coated target cells. Whereas the ectodomain of CD16 is the receptor for Fc gamma domains of immunoglobulins, disulfide-linked homo- and heterodimers composed of zeta and gamma are required for the cell surface expression, and signal transduction properties of the complex. Engagement of CD16 activates the tyrosine kinase pathway, which induces the tyrosine phosphorylation of several substrates, including the zeta subunit and the phospholipase C gamma-1 and gamma-2 isoforms. Here we show that CD16 stimulation of either peripheral blood NK cells, leukemic NK cells, or Jurkat transformants expressing a CD16: zeta: gamma receptor complex, results in the tyrosine phosphorylation of a 70 kDa zeta-associated protein (pp70). Similarly, a 70-kDa zeta-associated phosphoprotein in T cells has been shown to be a tyrosine kinase (ZAP-70). Peptide mapping analysis indicates that the 70-kDa zeta-associated phosphoproteins from T cells and NK cells are structurally indistinguishable. We conclude that the CD16: zeta: gamma complex may use a ZAP-70-related non-receptor tyrosine kinase, in the CD16 signaling cascade leading to NK cell activation.

Humans↗