Micromethods for induction and assay of mouse mixed lymphocyte reactions and cytotoxicity

A new method in which induction of mixed lymphocyte responses and cytotoxicity can be performed under identical conditions is described. This enables the investigation of the relationship between MLR and cytotoxicity. A micro method for the 51Cr release assay for cytotoxicity is described using both mitogen-induced blasts and tumors as target cells. Under the conditions used data obtained is suitable for linear regression analysis, enabling quantitative comparisons to be made.

Stimulation of mixed lymphocyte cultures and cytotoxic responses: evidence that T cells express SD but not LD antigens, whereas B cells express both

By separating T and B cells from stimulator spleens it has been found that mixed lymphocyte response (MLR) and cytotoxic cells are generated in responder T cell populations by B but not by T stimulator cells in a wide variety of strain combinations. It is suggested that MLR-stimulating or LD antigens are expressed on B but not T cells, and that their presence is necessary in order to generate cototoxic responses to H-2K and/or H-2D (or SD) antigens which are present on both T and B cells. The finding that B cells and macrophages stimulate MLR is consistent with the hypothesis that Ia antigens, expressed on both these cell types but not on nylon column purified peripheral T cells, are the MLR-stimulating or LD determinants.

The differentiation of cytotoxic T lymphocytes in vitro: an ultrastructural study

T killer cells were identified morphologically in two different culture systems. The first system allowed identification by comparing under identical culture conditions two types of stimulation, one leading to cytotoxic activity levels that were very high (H-2 stimulation) and the other to levels which were practically nil (M-locus stimulation). A second system allowed identification by the use of a collaborative system in which relatively pure precursors of T killer cells were mixed with precursors of T amplifier cells from which they were distinguishable by their Thy-l antigen. In this latter case, surface labelling techniques had to be used. As in the in vivo situation, T killer cells were medium-sized pale cells with evidence of a well-developed secretory and motile apparatus. No evidence of highly active protein synthesis was found. Other T cells were dark and mainly derived from the T amplifier population, again consistent with in vivo findings. There was considerable background proliferation, even in the absence of any added antigen, and this included the formation of some well-developed plasma cells.

Immunological reactivity of B mice reconstituted with various numbers of syngeneic bone marrow cells

Adult thymectomized mice were sublethally irradiated and reconstituted with various doses of syngeneic bone marrow. Immunological reactivity was assessed by allogeneic skin grafting at various intervals after reconstitution. It was found that reconstitution with high doses (1 X 10(7), 2 X 10(7)) of bone marrow was associated with an ability to reject allogeneic skin grafts and that this reactivity increased with time. Following rejection of a first skin graft, second grafts were rejected in an accelerated manner. These mice had measurable levels of Thy 1.2 positive cells in the spleen. In contrast, low-dose bone marrow reconstitution (1 X 10(6), 2 X10(6)) produced mice which did not reject either first or second allogeneic skin grafts, and such mice had at most only very low levels of Thy 1.2 positive cells in their spleens.

In vitro cell-mediated immune responses to the male specific(H-Y) antigen in mice

C57BL/10 female mice were primed to the male specific antigen H-Y, either by grafting with syngeneic male tail skin or by i.p. injection of syngeneic male spleen cells. Primed female spleen cells, either unseparated or filtered through nylon wool to remove most of the B lymphocytes, were then cultured for 5 days in vitro with irradiated syngeneic male spleen cells and assayed against 51Cr-labeled target cells. Both unseparated and nylon wool filtered female cells displayed significant cytotoxic activity restricted to male target cells. Pretreatment of sensitized female cells with antitheta serum and complement just before assay abolished cytotoxic responses. We were unable to demonstrate cell-mediated cytotoxic responses into two nonresponding strains, CBA and B10.A, which fail to reject male isografts. The cytotoxic activity of C57BL/10 female cells was restricted to male target cells histocompatible with C57BL/10 over at least a portion of the major (H-2) histocompatibility complex. We conclude that secondary in vitro cytotoxic responses against the H-Y antigen are mediated by cytotoxic T lymphocytes, and that the H-Y target cell antigen may be specified by the H-2 complex.

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.

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.

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.

Immunological disease induced by injecting F1 lymphoid cells into certain parental strains

Injection of neonatal Balb/c or C57Bl/6 mice with C57Bl/6 x Balb/c)F1 lymphoid cells leads to transient chimerism and runting, and to splenomegaly, deficient T-cell function and a gradual replacement of lymphoid organs with abnormal reticular cells. Activated MuLV can be isolated from such mice. It is proposed that either graft-versus-host or host-versus-graft allogeneic reactivity activates endogenous MuLV virus, which then causes functional and morphological abnormalities in the lymphoid organs.

An evaluation of a drug administration system in a psychiatric hospital

Previous studies have shown that in-patients in psychiatric hospitals may not always take prescribed drugs reliably (Hare and Wilcox, 1967; Wilson and Enoch, 1967; Irwinet al., 1971).

The histological response to a xenogeneic tumour in mice

We have examined, by conventional histological methods, the immune response of normal and ALS-treated mice to a tumour xenograft. In normal mice the histology of the tumour site and lymphoid organs is in agreement with the hypothesis that rejection of tumour is by a cell-mediated response. In ALS-treated mice, lymphoid organs severely depleted of small lymphocytes, show many blast cells which may be responsible for in vitro cytotoxicity. After cessation of ALS there is still a striking lack of infiltrate at the tumour site suggestive of some form of `blocking' mechanism.

Screening for Paracetamol Poisoning

The commonly used tests for the detection of paracetamol or its metabolites in cases of self-poisoning are either non-specific or time consuming. The need for screening all cases of self-poisoning for paracetamol ingestion is emphasised and a test is recommended which combines the advantages of increased specificity with those of a short procedure.