Biomedical subjects

R T Smith

Publications and source records attributed to R T Smith.

At least 109 records · Page 6Linked to original sources

PubMed1975

Tumor-secific immunity to chemically induced tumors. Evidence for immunologic specificity and shared antigenicity in lymphocyte responses to soluble tumor antigens.

Experiments were designed to explore the apparent paradox that methylcholanthrene-induced tumors of mice evoke tumor-unique transplantation immunity but reveal almost complete cross-reacting antigenicity in tests of lymphocyte behavior in vitro. The approach involved use of tumor membranes solubilized in 3 M KCl, employed both as the stimulating antigen source in a new in vitro proliferation assay of lymphocyte recognition, and as immunogens in vivo. The kinetics of the assay resembled those of in vitro tests of mitogen or specific antigen stimulation in other systems. Lymphoid cell proliferation was assessed in peripheral blood leukocytes, lymph nodes (LN), and spleen over the course of tumor bearing, and in animals immunized by tumor amputation or with the solubilized antigens. The pattern of spread of reactivity was from regional LN to spleen, peripheral blood, and nonregional nodes in each circumstance. An unexplained low antigen dose inhibitory phenomenon was encountered in spontaneously proliferating cell subpopulations taken from some tumor-bearing animals. In vitro responses to some but not all solubilized antigens made from multiple syngeneic tumors were detected in each circumstance. The soluble antigens also induced shared resistance to some tumors. The patterns of spread of responsiveness to syngeneic tumor antigens, the time-course, and relative intensity were most compatible with independent clonal responses to multiple tumor-borne antigens, some but not all of which are shared in any family of syngeneic tumors.

Animals↗

PubMed1975

Evidence for a B-cell -like helper function in mixed lymphocyte culture between immunocompetent thymus cells.

The immunocompetent subpopulation by mouse thymus cell (TH-2) was isolated by buoyant density centrifugation and by hydrocortisone pretreatment. TH-2 cells undergo a proliferative one-way or two-way mixed lymphocyte culture (MLC) response only when cultured with allogeneic or congenic peripheral lymphoid cells. However, mixtures of allogeneic TH-2 cells alone do not proliferate in either one-way or two-way MLC reactions. Such MLC mixtures are proliferative only if mitomycin-blocked peripheral lymphoid cells are also present in the mixture. The peripheral helper cell has been found to be of low net density, non-adherent, insensitive to anti-thy-1 serum cytotoxicity, but sensitive to the cytotoxic effets of anti-immunoglobulin serume plus complement. The helper effect does not depend on proliferation nor does it appear to involve demonstrable soluble mediators. The nature of failure of MLC between TH-2 subpopulations appears to be dependent on the exppression of some product of the K, I regions of the H-2 locus. Possible mechanisms by which a B-cell-like helper cell triggers TH-2 proliferation are discussed terms of the present knowledge of specific alloantigen receptor on T and B cells, and the immunoglobulin Fc region receptors on T cells.

Animals↗

PubMed1975

Effects of enforced relocation on life adjustment in a nursing home.

A group of 75 institutionalized elderly patients was studied to determine the relationship of involuntary relocation to life adjustment in a nursing home. Data were collected by means of medical records and structured questionnaire. Patients who had experienced enforced relocation from other institutions expressed greater life dissatisfaction than those who had relocated voluntarily fissatisfaction was correlated with financial dependence, poor health, and limited social participation. Length of stay in the institution was not related to life satisfaction. The evidence suggests that involuntary placement, multiple moves, disruption of social networks, and financial dependence may contribute to life dissatisfaction among institutionalized elderly.

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PubMed1975

T mitogens trigger LPS responsiveness in mouse thymus cells.

Mouse thymus cells are essentially unresponsive to lipopolysaccharide (LPS) stimulation. However, when cultured with minimally mitogenic levels of concanavalin A or submitogenic ratios of mitomycin-treated allogeneic spleen cells, in combination with LPS, they demonstrate levels of DNA synthesis de novo or greater than those induced by the T cell mitogen alone. Dose-response kinetics were characteristic of LPS. The subpopulation containing the LPS responsive cells was of low net buoyant density. Neither phytohemagglutinin nor pokeweed mitogen acted synergistically with LPS in this model to trigger thymus cells. The data suggest that LPS triggering may involve interaction with a T cell subpopulation.

Animals↗

PubMed1974

Clonal character of F1 hybrid lymphocyte subset recognition of parental cells in one-way mixed lymphocyte cultures.

Proliferation of F(1) hybrid lymphocytes in mixed lymphocyte cultures is stimulated by mitomycin-blocked parental cells. The demonstration of this phenomenon using F(1) hybrids derived from congenic lines of mice establishes that the stimulation is controlled by genes in or closely linked to the major histocompatibility locus chromosome region. In agreement with the finding that tumor-bearing mice have an increased capacity for primary alloantigen recognition, it was observed that the F(1) hybrid response to parent was also augmented by tumor bearing. Chromosomal analysis of dividing cells in one-way mixed cultures confirms that F(1) cells, and not the blocked parental cells, enter mitosis. Stimulation of F(1) cells by a soluble mediator liberated by the parental cells was not observed and mitomycin blocking of parental cells seems to be a completely effective blocking agent ensuring that parental cells can not enter DNA synthesis. The specificity and clonal nature of F(1) recognition of parent was demonstrated using a 5-bromodeoxyuridine-suicide procedure. Distinct clones of lymphocytes in F(1) spleen cell populations seem to recognize one or the other parent, but not both, in such experiments. These observations and others in tumor systems suggest that most or all heterozygous organisms may possess potentially self-reactive clones of lymphocytes.

Animals↗

PubMed1974