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Biomedical subjects

E M Levy

Publications and source records attributed to E M Levy.

35 records · Page 2Linked to original sources
PubMed1981

Countercurrent distribution of human peripheral blood lymphocytes: isolation of a subpopulation enriched with natural killer and K cells.

Aqueous solutions of dextran and of poly(ethylene glycol) when mixed give rise to two-phase systems suitable for the separation by partitioning of cells based on subtle differences in their membrane surface properties. Human peripheral blood mononuclear cells were obtained by centrifuging blood over Hypaque-Ficoll and removing the cells from the cushion. Clean lymphocytes were then isolated by velocity sedimentation of the mononuclear cells. Lymphocytes were subjected to countercurrent distribution (i.e., a multiple extraction procedure) in a two-polymer aqueous phase system which separates cells primarily on the bases of surface charge-associated properties. It was found that a small subpopulation of cells with highest partition coefficient (presumably highest surface charge-associated properties) contain virtually all of the natural killer (NK) and K cell activities.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1981

A comparison of the suppressor cells found in the spleens of 89SR-treated mice and in normal murine bone marrow.

Normal murine bone marrow cells and spleen cells of mice treated with 89Sr both have suppressive activity. These nonspecific suppressor cells inhibit the ability of normal spleen cells to undergo antibody responses in vitro. After being precultured for 24 hr, these cells will also suppress antibody responses in vivo and the responses of normal spleen cells to T and B cell mitogens in vitro. These cells have previously been shown not to be mature T or B lymphocytes or macrophages. Velocity sedimentation and cell-size analysis indicated that both suppressor cells are large (approximately 206 mu3). Mitomycin C treatment eliminated the ability of both suppressor cells to inhibit an in vitro antibody response. In contrast, this treatment did not reduce the ability of the cells to suppress a mitogenic response. Irradiation (1000 R) was also ineffective in eliminating the ability of either cell to suppress a mitogenic response We conclude that the 2 suppressor cells are closely related if not identical, and we speculate that these cells may function in vivo to suppress immune reactivity in areas of intense hematopoiesis.

Animals↗
PubMed1980

The ability of horse serum to support an in vitro antibody response.

It was found that 10% horse serum (HrS) could be used to support an in vitro antibody response to SRBC. It could replace the fetal calf serum (FCS) in both the culture medium and the nutritional feed. The response could be improved by the addition of 2-mercaptoethanol or by including both FCS (5%) and HrS (5%) in the culture medium.

Animals↗
PubMed1978

In vitro activation of suppressor cells from spleens of mice treated with radioactive strontium.

Mice were treated with two 100-muCi injections of 89Sr to deplete marrow-dependent (M) cells. Mice so treated responded normally to immunization with sheep red blood cells (SRBC) in vivo; moreover, spleen cells from 89Sr-treated mice were able to respond to SRBC after infusion into irradiated recipient mice. However, spleen cells from mice treated with 89Sr did not respond to SRBC in vitro and mixtures of normal spleen cells with the latter were also not able to respond in vitro. The discrepancy between in vivo and in vitro responses was abolished by culturing spleen cells for 24 hr before testing their ability to respond to SRBC in the adoptive transfer in vivo. Pretreatment of spleen cells from 89Sr-treated mice with 1000 R of gamma-radiation lessened their suppressive activity. The suppressor cells were detected in spleens of athymic nude mice treated with 89Sr. The suppressive activity, after the 24-hr culture period, was not abolished by irradiation and was active in vivo as well as in vitro. Thus, depletion of M cells by 89Sr results in the appearance within the spleen of thymus-independent suppressor cells, which require a short period of in vitro cultivation before becoming functionally active.

Animals↗
PubMed1977

Enrichment of the murine natural killer (NK) and mitogen induced cellular cytotoxicity (MICC) cells using preparative free-flow high voltage electrophoresis.

A procedure using preparative free-flow high voltage electrophoresis is described for the fractionation of murine spleen and bone marrow cells so as to obtain cell subpopulations that are either enriched in or depleted of "natural killer" (NK) cells and "mitogen-induced cellular cytotoxicity" (MICC) effector cells. A nearly three fold enrichment in the NK and MICC activities of spleen cells was achieved. The enrichment in these cells could be further increased if the phagocytic cells were removed prior to electrophoresis. When bone marrow cells were fractionated a two and a half fold increase of NK activity, and a one and a half fold enrichment of MICC activity was achieved. In both cases, other fractions were nearly devoid of NK and MICC activity. The cell recovery after electrophoresis averages 70% of the cells applied, and at least 90% of these cells were viable. MICC and NK effector cells could not be separated to a useful extent electrophoretically but were found to be separable using Sephadex C-10 gel filtration columns. The MICC but not the NK cells were retained on these columns.

Animals↗
PubMedDate not supplied

Short-term immunological effects of induced emotion.

Twenty healthy volunteers (half male) recalled and relived maximally disturbing (NEG) and maximally pleasurable (POS) emotional experiences. Forty minutes of silence, then neutral conversation, preceded and followed 40 minutes of emotion elicitation (NEG and POS randomly rotated). They were under video, cardiovascular, and immunological monitoring. Subjects reported appropriate emotions and showed significant cardiovascular activation during the NEG condition. Speech alone had an independent cardiovascular activating effect. Emotion, particularly NEG, led to further activation. NEG emotion promoted significant declines in mitogenic lymphocyte reactivity, followed by return to pre-emotion levels. A similar though less extreme decline was seen in the POS condition. There was a weak trend for elevated natural killer cell activity under the NEG condition, possibly due in part to changed trafficking patterns. Correlational findings confirmed these group effects. The decline in mitogenic reactivity during POS emotion appeared to be due to subtle degrees of tension and excitement triggered by the experimental experience regardless of the exact emotions recalled. Results suggest that immunologic processes are sensitive to influence by arousal of emotion.

Adaptation, Psychological↗