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Biomedical subjects

J L Turk

Publications and source records attributed to J L Turk.

At least 235 records · Page 13Linked to original sources
PubMed1975

Epicutaneous induction of hyporeactivity in contact sensitization. Demonstration of suppressor cells induced by contact with 2,4-dinitrothiocyanatebenzene.

Partial unresponsiveness to 2,4-dinitrofluorobenzene (DNFB) was produced by the epicutaneous application of 2 per cent 2,4-dinitrothiocyanatebenzene (DNTB) to the dorsum of the ear, 14 and 7 days before sensitization. This state of partial unresponsiveness could be broken by treatment with 300 mg/kg cyclophosphamide (CY) 3 days before the sensitization dose of DNFB. There was a significant increase in the uptake of 125I-labelled iododeoxyuridine in the draining lymph node, 6 days after the application of 2 per cent DNTB and in the contralateral nodes at 4 and 6 days. The state of partial unresponsiveness to DNFB was not associated with a decrease in T-cell proliferation in the draining lymph nodes. The generation of suppressor cells, capable of reacting in the periphery, was demonstrated by passive cell transfer into recipients sensitized to DNFB and depleted of normally produced suppressor cells by pretreatment with CY. These cells were found in spleen and peritoneal exudates of animals treated by the epicutaneous application of 2 per cent DNTB 14 and 7 days previously. It is suggested that the suppressor cells induced by contact with DNTB act by competition with effector cells at the periphery.

Animals↗
PubMed1975

Binding of aggregated human immunoglobulin to murine thymocytes and T cells through receptors for the Fc region.

Normal thymus lymphocytes and T cells of mice have the ability to bind heat-aggregated IgG of human origin (aggHIgG), as shown by indirect immunofluorescence. At 4 degrees, the cells bind aggHIgG with an irregular speckled appearance; at 37 degrees, the aggregates are incorporated into the surface membrane, inducing rearrangement of the receptors and capping. At the point of maximum binding capacity, thymocytes show a fairly homogeneous fluorescence pattern, whereas T cells show a heterogeneous appearance. Aggregated pure human Fc fragments, but not Fab fragments, retained not only the binding capacity of the complete molecule but also the ability to induce cap formation on the surface of thymusceds, at 37 degrees.

Animals↗
PubMed1975

Rapid quantitation of changes in macrophage volume induced by lymphokine in vitro.

A new machine, the Coulter Channelyzer P128, has been used to measure the mean cell volume of suspensions of normal guinea-pig macrophages. Macrophage volume, expressed in cubic microns, has been examined after various times of storage and subsequently after contact with varying concentrations of lymphokine. It is suggested that this machine improves the speed and accuracy of quantitating one in vitro assay of lymphokine activity.

Animals↗
PubMed1975

Reversal by cyclophosphamide of tolerance in contact sensitization. Tolerance induced by prior feeding with DNCB.

Tolerance to DNCB induced by feeding guinea-pigs with the same hapten has been reversed by a single treatment with cyclophosphamide. This is paralleled by a return of the ability of T cells to proliferate in the draining lymph node following sensitization. Certain quantitative differences between this system and that previously described using intravenous DNBSO3 have been revealed. These may indicate some difference between these two mechanisms of tolerance induction.

Animals↗
PubMed1975

Immunological mechanisms in the reaction between drugs and the skin.

Many reactions in the skin caused by drugs would appear to be due to immunological mechanisms. Simple chemical sensitizers become antigenic after combination with carrier proteins. The bonds between the hapten and the protein are not necessarily covalent, and it is likely that weaker linkages such as hydrogen bonding or Van der Waal's forces may be involved. Reactions may be due to humoral antibody or cell-mediated immunity. Experimental models are discussed in which there is competition between B suppressor cells and T effector cells. In these situations, drugs that affect the suppressor cell system specifically can reverse a state of immunological tolerance or increase the intensity of a chemical sensitivity. Finally, the mechanism of fixed drug eruptions is discussed. It is suggested that the actions which follow the systemic absorption of the chemical and always occur at this same site are due to B cells or B cell products that remain from a previous delayed hypersensitivity reaction to the same antigen. These cells would have arrived initially as part of the non-specific inflammatory infiltrate. The initial reaction may even have been subliminal in intensity.

Animals↗
PubMed1974

Johann R. Frey.

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Allergy and Immunology↗