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Biomedical subjects

B R Bloom

Publications and source records attributed to B R Bloom.

At least 253 records · Page 14Linked to original sources
PubMed1977

Deficient mitogen-induced virus plaque-forming cells in patients with localized cancer.

The virus plaque assay (VPA), an assay capable of enumerating mitogen- or antigen-sensitive T-lymphocytes in a given cell population, was applied to the study of mitogen responses of peripheral blood leukocytes (PBL) in 50 patients with localized, solid cancers and in 29 normal controls. Concanavalin A (Con A)-responsive virus plaque-forming cells (V-PFC) were significantly reduced in the patients as compared with those of the controls. PBL from 20 of the patients but only 2 of the controls failed to show significant increments in V-PFC over background when cultured in the presence of Con A. This deficient response was also present in the patients when phytohemagglutinin was used as the mitogenic agent. Mitogen-stimulated uptake of [3H]thymidine (TdR) in parallel cultures failed to show a statistically significant difference between the patients and the controls, though some patients showed diminished stimulation in this assay. The VPA thus appeared to detect a defect of T-lymphocyte function not found in the [3H]TdR incorporation assay.

Cell Separation↗
PubMed1977

Modulation of Fc-mediated phagocytosis by cyclic AMP and insulin in a macrophage-like cell line.

Studies on genetically selected mutants in phagocytosis of E[IgG] indicated that the defect in some mutants could be corrected by addition of 8 Br-cAMP, and suggested that cyclic AMP may be involved in the mechanism of phagocytosis through the Fc receptor. In order to elucidate the role of cyclic AMP in phagocytosis in the parental, nonmutant macrophage-like cell line, J774.2, it was necessary to employ restrictive conditions which rendered phagocytosis suboptimal. When 4774.2 cells were cultured in nontissue culture Petri dishes phagocytosis was markedly reduced. Addition of 8 Br-cAMP or inducers of intracellular cyclic AMP such as isoproterenol restored the phagocytic ability of these cells. Similarly, treatment of the parental J774.2 cells with insulin reduced the level of phagocytosis, and once again this suppression could be corrected by addition of 8 Br-cAMP. In no case did AMP mimic the effects of 8 Br-cAMP. The effect of cyclic AMP action in this system was not instantaneous, but rather reached optimal levels at 5 to 10 hr, suggesting that cyclic AMP is not the immediate signal for phagocytosis. The genetic analysis of macrophage variants may provide a useful model for studies on the mechanisms of phagocytosis, and also the effects of insulin and cyclic AMP on an easily measurable biologic function in a specialized cell type.

Cell Line↗
PubMed1976

Inhibition of leukocyte migration by human breast-cancer-associated antigens.

The existence of CMI to tumor-associated antigens present in 3 M KCl extracts of breast carcinomas was demonstrated in a group of breast cancer patients by the leukocyte migration inhibition (LMI) assay. When crude KCl extracts were tested, 3 of 5 breast cancer patients gave a positive response to autologous tumor extracts. Eleven of 20 gave a positive response to allogeneic extracts as compared to 3 of 22 controls (including 6 patients with benign breast disease, 7 with non-mammary cancers and 9 normal controls). Extracts of fibrocystic disease tissue gave positive LMI tests in 2 of 5 breast cancer patients, suggesting the presence of antigenic cross-reactivity between benign and malignant breast disease. An extract of a medullary carcinoma of breast was fractionated on Sephadex G-200 and the effluent pooled into three fractions. The high molecular weight fraction produced LMI in 11 of 22 breast cancer patients and in 1 of 19 controls, including patients with benign breast disease, other cancers and normal individuals. The low molecular weight fraction produced LMI in both the benign (4 of 6) and the malignant breast disease (6 of 20) patients, but not in the controls (0 of 12). A simple fractionation technique has thus separated "cancer-specific" from "organ-specific" activity. Sephadex G-200 fractions were active at a much lower protein concentration than the crude 3 M KCl extracts.

Adenofibroma↗
PubMed1976

Regulatory variants for the expression of H-2 antigens. II. Level of discrimination of cell-mediated cytolysis.

We used alloantigenic variants to analyze whether killer T-cells and antibody in the presence of complement (two effector components of the immune system) recognized the same determinants on target tissues. The variants were selected from mouse myeloma cells by immune selection and differed from the parent cell in that they did not express H-2 antigens. The results suggested that both killer T-cells and humoral effectors recognized the same determinants, though the killer T-cells may have been more sensitive either in recognizing these determinants or mediating lysis.

Animals↗
PubMed1976

Blocking of MLC stimulation by anti-Ia sera: studies with the virus plaque assay.

The development of congenic mouse strains identical at the H-2K and H-2D loci but differing by I-region associated (Ia) determinants has permitted an association to be established between Ia determinants and stimulation in mixed lymphocyte culture reactions (MLR). The present experiments were undertaken to establish whether the Ir-coded control of MLR operated at the level of recognition or of stimulation. Reciprocal MLR were established between A.TH and A.TL mouse spleen cells in the presence or absence of anti-Ia sera directed either at determinants of the stimulating or responding cells. The number of T cells responding was assessed by the virus plaque assay. Anti-Ia sera directed against the responding cells were no more inhibitory of the MLR than normal mouse serum. In contrast, anti-Ia sera directed against determinants of the mitomycin-treated stimulating cells markedly inhibited activation of T cells in the MLR.

Animals↗
PubMed1975

Requirement for T cells in the production of migration inhibitory factor.

The question whether B lymphocytes are capable of being activated by antigen in the absence of functional T cells was investigated in a model that excludes participation of T cells by virtue of an immune response gene restriction. Strain 2 guinea pigs are capable of responding to immunization with DNP-PLL, whereas strain 13 animals are not. In the present experiments, animals of both strains were immunized with DNP-PLL complexed to ovalbumin (DNP-PLL-Ova) under conditions in which equal titers of antibodies to DNP were produced by both strains. The failure of T cells of strain 13 animals to respond to DNP-PLL was confirmed by the virus plaque assay. While spleen cells from both strains produced MIF after stimulation with DNP-PLL-Ova, in response to DNP-PLL only strain 2 spleens were able to produce MIF. Cells from neither strain could be activated by DNP-guinea pig albumin to produce MIF. We conclude that B lymphocytes are incapable of being stimulated by antigen in the absence of T cells, and that MIF production is a thymus-dependent response. While the results indicate that MIF production is a valid qualitative assay for T-cell competence, since MIF can be produced by B and T cells, the degree of migration inhibition cannot be regarded as a quantitative measure of T-cell function.

Animals↗
PubMed1975

Primary demyelination as a nonspecific consequence of a cell-mediated immune reaction.

Primary demyelination occurs in a variety of human and experimental diseases known to be associated with the presence of inflammatory cells. However, the mechanism of demyelination remains unclear. The possibility that myelin can be damaged as a nonspecific consequence of a specific delayed type of hypersensitivity reaction directed at nonnervous tissue antigens was investigated. Guinea pigs were sensitized to tuberculin with Freund's complete adjuvant, and were challenged in the central and peripheral nervous system either with live or killed sonicated tubercle bacilli, Old Tuberculin, or tuberculin purified protein derivative (PPD). Local inflammatory reactions were invariably produced and primary demyelination was a constant feature of the lesions. The morphological picture was rather similar to that observed in human neurotuberculosis and early tuberculoid leprosy, and in experimental allergic encephalomyelitis and distemper encephalitis in animals. The infiltrates consisted predominantly of mononuclear cells with some polymorphonuclear cells as well. Vesicular disruption of the myelin sheath in the immediate vicinity of the inflammatory cells and stripping of the myelin lamellae by the histiocytes without axonal damage were the leading features of the lesion. The results indicate that cell-mediated immune reactions to a variety of nonbrain antigens could be responsible for a component of the demyelination seen in some inflammatory demyelinating conditions, and suggest that this system may serve as a useful model for studying the immunopathology of demyelinating disease.

Animals↗
PubMed1975

Production of migration inhibitory factor and lymphotoxin by non-T cells.

Treatment of tuberculin-sensitive guinea pig spleen or lymph node cells with a burro anti-T cell serum plus complement diminished markedly the number of functionally detectable T cells, but did not affect the amount of migration inhibitory factor (MIF) or lymphotoxin produced by the residual T cell-depleted populations.

Animals↗
PubMed1975

Experimental allergic optic neuritis (EAON) in the rabbit. A new model to study primary demyelinating diseases.

In New Zealand albino rabbits the axons of the nerve fibre layer are myelinated over a long distance within the retina. Primary demyelination of these fibres was induced by sensitization of the animals to bovine cerebral white matter or myelin basic protein in complete Freund's adjuvant and challenge thereafter by intravitreous injection of basic protein (BP) or purified tuberculin (PPD). Production of segmental demyelination as a result of sensitization to brain-specific antigen (BP) and indifferent (PPD) antigen, shows that morphologically the same type of lesions can be induced by any antigen which will elicit cell-mediated immune reaction.

Animals↗