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J J Burckhardt

Publications and source records attributed to J J Burckhardt.

27 records · Page 2Linked to original sources
PubMed1979

Rat memory T lymphocytes. II. Differences in macrophage-dependent activation shown by Actinomyces viscosus antigens and by mitogens, using silica in vitro.

Protein-coated silica, a macrophage toxin, was used to assess the requirement for accessory cells in the induction of an in vitro proliferative response to (i) antigens from Actinomyces viscosus and (ii) the mitogens conconavalin A (Con A) and phytohaemagglutinin (PHA). T cells were obtained from RIC-Sprague-Dawley rats primed in vivo with A. viscosus Nyl by splenectomy and filtering the spleen cell suspensions through Degalan Ig-anti-IgG columns. In the presence of 100 microgram silica/ml during 4 days of culture, the proliferative response of T lymphocytes was not diminished. In contrast, when the T cells were precultured with silica for 24 h, washed, and subsequently cultured with the antigen fractions, antigen-induced proliferation was abolished. This procedure, however, had no influence on mitogen-induced proliferation was abolished. This procedure, however, had no influence on mitogen-induced T-cell activation. It is therefore concluded that the antigen-dependent anamnestic in vitro response (but not activation by mitogens) of rat T lymphocytes needs help from silica-sensitive macrophages.

Actinomyces↗
PubMed1979

Cyclosporin A: in vivo and in vitro suppression of rat T-lymphocyte function.

The immunosuppressive effect of cyclosporin A (CS-A) was investigated in RIC-Sprague-Dawley rats. In vivo, CS-A totally abolished the formation of antibodies to the hapten dinitrophenyl (DNP) in rats immunized with DNP-keyhole limpet haemocyanin. In vitro, the effect of CS-A was investigated in spleen cell cultures stimulated by concanavalin A, phytohaemagglutinin or lipopolysaccharide. The suppression due to CS-A was more pronounced in cultures set up with cells from rats fed the drug than in spleen cell cultures from control animals supplemented with serum containing CS-A. Purified by filtration through Degalan-rat Ig-anti IgG columns, T lymphocytes from CS-A treated rats were no longer suppressed by CS-A serum in contrast to purified T cells obtained from control rats. Thus, CS-A seems to interfere with the mitogenic triggering of a subpopulation of T lymphocytes resulting in a functional clonal deletion.

Animals↗
PubMed1978

Rat memory T lymphocytes: in vitro proliferation induced by antigens of Actinomyces viscosus.

Peripheral T lymphocytes from RIC-Sprague-Dawley rats primed in vivo several months earlier with Actinomyces viscosus Ny 1 reacted with a strong proliferative response upon antigenic challenge in vitro. Two different antigen preparations from A. viscosus Ny 1, a broken cell supernatant (BCS) and an extracellular fraction (EXC) gave maximum responses as measured by the uptake of [3H]thymidine at a concentration of 10 microgram at day 4 of culture. Phytohaemagglutinin (PHA) used as a control provoked a maximum proliferation in the same order of magnitude. T lymphocytes from unprimed, germfree and conventional animals showed a similar stimulation to PHA, but only a marginal reaction to BCS, and were not at all activated by EXC. Evidence is thus presented for efficient removal of cells responding non-specifically to B-cell mitogens.

Actinomyces↗
PubMed1977

Are Actinomyces viscosus antigens B cell mitogens?

An extracellular heteroglycan (ECHG) and a sonicated cell supernatant (SCS) of Actinomyces viscosus Ny 1 induced strong lymphocyte proliferation. This was shown with spleen and thoracic duct cells form germfree rats and confirmed with cells from conventional "nude" mouse spleens. Spleen cells developed direct plaque-forming cells against densely coupled TNP-SRBC. The mitogenic property of ECHG was diminished considerably after mild alkaline hydrolysis for lymphocytes form rat spleens and was totally abolished for cells from "nude" mouse spleens. These results suggest that ECHG and SCS have B cell mitogenicity.

Actinomyces↗
PubMed1976

Interactions of antisera, sera, and oral fluid with glucosyltransferases.

Partially purified glucosyltransferases (GTF) isolated from Streptococcus mutans OMZ 176 and respective rabbit antisera were used to study enzyme-antibody interactions. A comparison between sensitive serological techniques and a functional inhibition test based on a radioenzyme assay demonstrated that the latter test system was the only one that discriminated between different antisera. Positive reactions in high dilutions in the former test systems were explained by the involvement of non-GTF contaminants and/or antibodies against enzyme regions distant to the catalytic site. The minute cross-reactions between two enzyme fractions and the respective antisera in the functional inhibition test indicated that the two immunogens contained mainly GTF that differed in the structure of their catalytic region. Control rabbit sera, rat oral fluid, and insoluble and soluble glucans considerably activated the GTF eluted with a 0.5 M phosphate buffer from hydroxapatite. It is suggested that these enzymes had additional binding sites for macromolecules inherent to rabbit sera and rat oral fluid, respectively, and that the observed increase in enzyme activity was due to a more stable enzyme conformation. Possibly the stimulation of GTF by the soluble glucan fraction was caused by a primer and/or acceptor function; however, this was not the case of the insoluble glucan. A stable complex was formed in the absence of the enzyme substrate, sucrose, the activity of which was not readily enhanced. It is concluded that the GTF of strain OMZ 176 are composed of multiple, multi-reactive molecules that enable these enzymes to act as cross-linking agents.

Absorption↗