Restricted rosette formation with an EAC reagent prepared with serum of C3H/HeJ mice.
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Animals↗
Biomedical subjects
N Bloksma
Publications and source records attributed to N Bloksma.
Regulation of the immune response by macrophages.
Regulation of the immune response by macrophages was studied with cellular resistance to Listeria monocytogenes as parameter. The use of agents which suppress macrophage activity during the induction-phase of immunity enabled the induction of protective immunity with killed listeria. Fractionation of the cell content of listeria yielded an RNA'se sensitive fraction which in a dose of 300 ng and in combination with the cationic surfactant dimethyl dioctadecyl ammonium bromide induced protective immunity against listeria.
Adjuvants, Immunologic↗
Modulation of delayed hypersensitivity in mice by cobra venom factor.
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Animals↗
Differential potencies of corticosterone and hydrocortisone in immune and immune-related processes in the mouse.
The effects of corticosterone and hydrocortisone on the thymus, the pituitary--adrenal axis, delayed hypersensitivity, the corticosterone plasma level and the numbers of circulating nucleated and monocytic cells were investigated in the mouse. Short-term effects within 48 h after one or two corticoid injections and late effects 7 days after a regimen of 4 corticoid injections were discerned. In short-term experiments hydrocortisone was more active than corticosterone upon the induction of leukopenia and monocytopenia and the inhibition of delayed hypersensitivity. However, regarding late effects and the short-term effect on adrenal weight, corticosterone far exceeded hydrocortisone in activity. Our results could be explained by assuming two feedback-inhibition systems for glycocorticoids. The first, likely to be responsible for the changes observed for the adrenal weight and the numbers of ciruclating white cells after a single glucocorticoid injection, was shown to be expressed in a soluble factor released in the blood stream tentatively designated "glucocorticoid inhibiting factor. The factor was more readily induced by hydrocortisone but displayed a greater specificity in inhibiting effects of corticosterone. The second feedback-inhibition system, responsible for increased numbers of circulating monocytes paralleled by an enhanced delayed hypersensitivity response, was expressed in a decreased corticosterone plasma level, most probably secondary to a diminished release of ACTH from the pituitary gland. With the glucocorticoid doses we used the second feedback-inhibition system was only triggered by the more physiological hormone, corticosterone.
Adrenal Glands↗
Adjuvanticity of lactobacilli. I. Differential effects of viable and killed bacteria.
The adjuvanticity of Lactobacillus brevis and Lactobacillus plantarum was the subject of this study. The latter was the better adjuvant in both delayed hypersensivity and antibody formation to sheep red blood cells. Viable L. plantarum stimulated exclusively the delayed hypersensivity, where heat-killed bacteria had an adjuvant effect on antibody formation. For optimal adjuvant effects lactobacilli had to be injected in a dose of 10(8) into the same site as the antigen. Viable lactobacilli and to a lesser degree heat-killed bacteria induce hepato-splenomegaly, suggesting mediation of the adjuvant activity by the reticuloendothelial system. Granuloma formation with mainly mononuclear cell infiltrates could be observed after subcutaneous administration of viable lactobacilli whereas heat-killed lactobacilli induced granulomata containing about equal numbers of granulocytes and mononuclear cells. The possible clinical application of L. plantarium in the immunotherapy of tumours is suggested.
Adjuvants, Immunologic↗
Cellular and humoral adjuvant activity of mistletoe extract.
The adjuvanticity of the mistletoe preparation Iscador was investigated. The cellular response to sheep red blood cells (SRBC) was augmented after intracutaneous immunization with antigen and different doses of Iscador. Iscador did not change the cellular response to 2 x 10(7) intraperitoneally administered SRBC. The IgM plaque forming cell response was accelerated and followed by an augmentation of the IgG and IgA plaque forming cell response. Evidence is presented that the immunogenic and inflammatory capacities of Iscador contribute to its adjuvant activity. Both micro-organisms and soluble, filter-adherent constituents in Iscador possess adjuvant activity. The relation between the immunostimulating properties of Iscador and its anti-tumour activity is discussed.
Adjuvants, Immunologic↗
Quantification of in vitro antibody secretion by immune spleen cells.
A simple method to study 19S anti-SRBC antibody production is described. This technique, performed by incubation of immune spleen cells, SRBC and C in the fluid phase, utilises photomeric estimation of antibody mediated haemoglobin release. The test is quicker and more accurate than the two-step haemolytic plaque assay (Jerne technique). In combination with the Jerne technique this method gives information about haemolysin production per PFC. This was maximal on day 2 and on day 6 after immunisation, and least on day 4. The steady state value was reached again at day 9. In principle this method is suitable for the estimation of IgG production.
Animals↗
Oxisuran and immune reactions: mediation of oxisuran action by the adrenal glands.
Oxisuran was tested in a TAR system and for the DH on SRBC. Besides immunosuppressive properties in the TAR and DH also mentioned by other authors, stimulation was found after prolonged administration. No effect of oxisuran on the humoral response was observed. The action of oxisuran was suggested to be indirect, effected by stimulation of the PAG system. Adrenalectomy of mice made animals non-liable for oxisuran action measured in the TAR assay. Oxisuran caused an increase of the corticosterone plasma level with a peak after four daily injections. This was paralleled by a peak in adrenal gland weight and a minimum in thymus size. The reduction in these effects after five injections (tachyphylaxis) suggest that a feedback mechanism is involved. Comparison of thymus weights after oxisuran and corticosterone administration indicates that a daily dose of 100 mg oxisuran/kg corresponds with 1.5 mg corticosterone/kg. The effects of oxisuran in the TAR and on the DH and the feedback phenomenon could be imitated with 1.5 mg corticosterone/kg. The mononuclear phagocyte has been proposed as the main target cell of oxisuran action, mediated by the PAG system.
Adrenal Glands↗
Factors that define the susceptibility of endothelial cells to tumor necrosis factor and lipid A.
Factors defining the previously established differences in susceptibility of endothelial cells to the tumor-necrotizing agents, tumor necrosis factor (TNF) and lipid A, were investigated. Venous and arterial endothelial cells isolated from bovine and human umbilical cords showed large differences in proliferation rate and susceptibility to TNF and lipid A as measured by [3H]thymidine incorporation. The faster proliferating cells appeared more strongly inhibited by the agents. Also, using different isolates of human venous endothelial cells a similar correlation between proliferation rate and degree of inhibition was found. Growth stimulation of human venous cells with endothelial cell growth factor, but not the growth factor combined with heparin, increased the inhibitory action of the agents. Influence of the serum source was investigated by culturing human and bovine cells in the presence of human or bovine serum. Lipid A, but not TNF, was more inhibitory to cells of both species when cultured in bovine serum as compared to human serum. Supernatant of cultured tumor cells and serum from tumor-bearing mice increased the inhibitory effects of the agents as well. Data show that the action of the tumor-necrotizing agents on endothelial cells is defined by various factors, such as origin of the cells and culture conditions. In general, factors promoting cell proliferation tended to increase the susceptibility of the cells to the agents. The reported high vulnerability of tumors, wound tissue and placenta to induction of hemorrhage by these agents may be partially due to an enhanced sensitivity of the fast proliferating endothelium in these tissues.
Animals↗
Multiple facets of induction of tumour necrosis.
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Animals↗
Effects of various coryneforms on mononuclear phagocyte system function and on production of tumour necrosis factor in mice.
Vaccines of 6 strains of the genera Corynebacterium and Propionibacterium were tested for induction of hepatosplenomegaly and stimulation of clearance of injected colloidal carbon and viable Listeria monocytogenes. These effects were compared with the ability of these strains to support the endotoxin-induced liberation of tumour necrosis factor, interferon and heat-stable cytostatic factors in mouse circulation. Five strains caused good stimulation of macrophage functions and induced high levels of all factors. One strain was nearly lacking in macrophage stimulatory capacity and also failed to support factor production. These data are discussed in relation to the production mechanisms of the factors.
Animals↗
Influence on macrophage functions as a possible basis of immunomodification by polyanions.
The effects of the polyanions, carrageenan, dextran sulphate, polyanetholesulphonate and suramin, on macrophage functions and on the complement system were studied. The function of phagosomes and lysosomes in vitro was inhibited by all polyanions but carrageenan whereas phagocytosis in vitro was enhanced by small doses of all polyanions. Interaction with complement occurred already at very low doses polyanion. On intraperitoneal administration, the polyanions inhibited the mononuclear phagocytic system as measured with the carbon clearance test. In some instances this was followed within 72 h by a stimulation. While polyanion injections caused an increase in spleen weight, the effects on the liver weight diverged. Our results and data of other authors suggest that the immunomodifying properties of the polyanions studied can be explained partly by drug-macrophage interaction, partly by indirectly mediated modulation of macrophage function.
Adjuvants, Immunologic↗