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Biomedical subjects

E Simpson

Publications and source records attributed to E Simpson.

At least 253 records · Page 14Linked to original sources
PubMed1975

Regulation of the immune response by subclasses of T lymphocytes. I. Interactions between pre-killer T cells and regulatory T cells obtained from peripheral lymphoid tissues of mice.

The generation of killer cells to alloantigens in vitro depends upon an interaction between two subclasses of peripheral T cells: "pre-killer" T cells and "regulatory" T cells. The pre-killer T cell, found in highest concentrations in peripheral lymph nodes of mice, is sensitive in vivo to the administration of small doses of anti-thymocyte serum (ATS) and is depleted in vitro by treatment with (a) anti-Thy-1.2 + C, (b) low doses (600 r) of x-irradiation. Specificity of pre-killer cells is supported by adsorption of pre-killer activity on appropriate allogeneic monolayers and by the specific absence of this activity from lymphoid tissues of mice rendered tolerant in neonatal life. Although T cells remaining in the spleen 2 days after a small dose of ATS (SPA-T) did not generate killer cells, this subset exerted substantial regulatory effects upon the generation of killer activity by pre-killer T cells. The addition of this population of regulatory T cells to small numbers of lymph node T cells (LN-T) resulted in substantial enhancement in the generation of killer cells from the LN-T pre-killers. The addition of SPA-T to larger numbers of LN-T (which produce strong responses alone), failed to enhance the response, and in some cases resulted in significant suppression which could not easily be accounted for by alteration in cell numbers in culture. Although amplifier activity was relatively radioresistant, "suppressor" activity was sensitive to relatively small doses of irradiation. The significance of this T-T interaction is discussed.

Animals↗
PubMed1975

Regulation of the immune response by subclasses of T lymphocytes. II. The effect of adult thymectomy upon humoral and cellular responses in mice.

The immunologic consequences resulting from thymectomy in adult life were investigated. Primary humoral responses were not diminished shortly after adult thymectomy, as judged by responses of intact thymectomized mice as well as by the ability of spleen cells from such mice to transfer primary responses. However, secondary humoral responses were substantially reduced in irradiated recipients of spleen cells from primed adult-thymectomized mice, suggesting that the thymus is required in adult life to maintain a population of cells important in the generation of immunologic helper memory. By contrast, small doses of anti-thymocyte serum, which primarily affect recirulating T cells, abrogated the primary humoral response, but allowed the subsequent development of immune memory. Using a technique permitting in vitro sensitization of purified T cells to alloantigens, it was shown that adult thymectomy increases the ability of T cells to generate primary cytotoxic responses, but had little effect upon the development of cytotoxic T memory activity. These experiments suggest that in adult life the thymus maintains a regulatory population of T cells in peripheral tissues which suppress early T cell differentiation to cytotoxic effector cells and potentiates the development of immune memory.

Age Factors↗
PubMed1975

Why measure blood barbiturates?

Phenobarbitone levels in the blood do not always provide a reliable guide in the management of the poisoned patient. They may rise in response to active treatment though the patient may be improving clinically. Some reasons for this are considered, with illustrations from three cases. It is concluded that the poor correlation of phenobarbitone levels with a patient's condition is due not to inadequate analytical techniques but to the poor representation of the "whole body" situation by a single blood specimen. The usefulness of analysing such specimens is questioned.

Adult↗