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L Toujas

Publications and source records attributed to L Toujas.

At least 55 records · Page 3Linked to original sources
PubMed1979

Resistance to tumor graft in mice treated with inactivated Brucella abortus cultured in smooth or rough phase.

Because killed Brucella abortus organisms cultured in smooth (S) or rough (R) phase were known to differentially influence humoral and cellular immune responses and to differ in their effects on T-dependent responses, the antitumor properties of killed B. abortus organisms, cultured in S- or R-phase and then inactivated, were compared in (C57BL/6 X DBA/2)F1 female mice with the use of 6 different transplantable tumors. In solid tumors, the antitumor effects produced by S-preparations were never improved by R-preparations. However, in ascites tumors, R-preparations gave the best antitumor results. These findings suggested that the defense mechanisms acrivated by immunostimulants may differ according to the site of tumor implantation. Among the other experimental factors studied, the route of B. abortus administration had a prominent role. Local injection at the site of tumor implantation before or after the graft gave better results than did systemic treatment. Systemic treatment could enhance the growth of Lewis tumor when applied 5 or 10 days before tumor graft but generally had an antitumor effect when given 1 day after the graft.

Animals↗
PubMed1978

Influence of the antigenicity of Brucella preparations on modulation of the immune response to sheep erythrocytes.

The relationship between the expression of surface antigenicity of inactivated Brucella and the immunostimulant properties on the sheep erythrocyte response was studied in mice. The agglutinogenic Brucella abortus B19S preparation was compared to two non-agglutinogenic preparations (B19R and PB), using the plaque-forming and rosette-forming cell tests. When Brucella and antigen were injected together, only non-agglutinogenic preparations, even used at low doses, were able to increase the plaque-forming and rosette-forming cell responses measured 4 days after immunization. When the interval between the previous injection of non-agglutinogenic preparations and that of the antigen increased or when they were injected 24 h after the antigen, the modification of those two responses was no longer observed. After day 4, for the simultaneous injection of Brucella and antigen, B19S and PB preparations induced the best responses; this effect was dose dependent. Thus, in the present experimental situation, the modification of the day 4 response appeared independent of those of the ensuing days.

Agglutination↗
PubMed1978

Modulation of immune response by killed Brucella abortus organisms: comparison of the effects of smooth and rough strains on T-dependent responses.

Inactivated Brucella abortus organisms of the smooth (S) or rough (R) strain were tested comparatively on two T-dependent immune responses: mixed-lymphocyte reaction and delayed-type hypersensitivity. The intravenous injection of S organisms depressed the two tests, whereas R organisms increased mixed-lymphocyte reaction and did not alter delayed-type hypersensitivity significantly. This observation may be helpful in understanding the differences in adjuvant properties of S and R brucellae.

Brucella abortus↗
PubMed1975

[Inhibition of antigenic competition by immunostimulants].

The diminution of immune response against SRBC induced in mice, by a prior injection of HRBC was counteracted by addition of certain immunostimulants to SRBC. The intensity of inhibition of antigenic competition was related to the quantity of immunostimulant added to SRBC. Some immunostimulants (B. abortus, lipopolysaccharide) were more active than others (C. parvum, Poly I : C). To inhibit antigenic competition immunostimulant had to be injected after or in mixture with SRBC never before.

Animals↗
PubMedDate not supplied

Autologous human macrophages and anti-tumour cell therapy.

Most technical problems concerning the production of human macrophages have been resolved by cultures in hydrophobic plastic, gas-permeable bags. This process enables collection of non-adherent macrophages and is well adapted to the safety requirements of cell therapy. Under optimized culture conditions, about one billion macrophages are currently obtained from a single leukapheresis product. In most clinical trials, macrophages have been activated by interferon-gamma (IFNgamma). The injections have little or no toxic effect. The anti-tumour activity of the intravenous (i.v.) administrations is more pronounced in certain protocols than in others. The mechanism remains poorly understood. In vitro, the cytolytic effect of macrophages requires cell-to-cell contact but macrophages injected i.v. show no particular tropism for tumour tissue. This could result from modifications in adhesion molecules occurring during monocyte-macrophage differentiation which might modify recruitment in inflammatory foci. Macrophages can, however, infiltrate tumour cell clusters, which could explain their improved efficacy when injected intratumorally (i.t.). Moreover, several arguments would favour the use of macrophages as human tumour antigen-presenting cells (APCs). In vitro, macrophages are as efficient as monocyte-derived dendritic cells (MDDCs) in stimulating cytotoxic T lymphocyte (CTL) clones or circulating CTL precursors.

Animals↗