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S Carding

Publications and source records attributed to S Carding.

10 recordsLinked to original sources
PubMed1989

A monoclonal antibody to murine CD45R distinguishes CD4 T cell populations that produce different cytokines.

CD4 T cell clones have been shown to be functionally heterogeneous in the mouse. However, it is not known if normal CD4 T cells are also functionally heterogeneous, or whether functional specialization is a result of cloning and long-term culture. To approach this question, a monoclonal antibody reacting with a subset of CD4 T cells has been prepared by immunization of rats with different cloned T cell lines all sharing the same functional activity. This monoclonal antibody reacts with a subset of CD45 (T200) molecules by binding to a determinant requiring the expression of the second variable exon of the CD45 molecule. Some CD4 T cells bear high levels of this marker, while others react only weakly. This antibody was used to separate CD4 T cells into two subpopulations. The brightly staining population was found to produce interleukin (IL) 2 and not IL 4, while the weakly staining population produced IL 4 and not IL 2. These data demonstrate that CD4 T cells in normal mice are already functionally committed, and that they differentially express forms of CD45 that contain the second variable exon.

Animals↗
PubMed1989

Progesterone and estradiol modulate interleukin-1 beta messenger ribonucleic acid levels in cultured human peripheral monocytes.

The relationship between the endocrine system and immune monokines, such as interleukin-1 (IL-1), is of increasing interest. IL-1, a protein secreted by peripheral monocytes and tissue macrophages, mediates a wide variety of immune responses, and its production appears to be inversely related to the level of gonadal steroids. In this report, we have investigated the relationship between estradiol and progesterone concentrations and the level of IL-1 beta mRNA in cultured human peripheral monocytes and pelvic macrophages. Human peripheral monocytes, isolated during the luteal phase of the menstrual cycle, were activated with lipopolysaccharide (10 micrograms/mL). Cellular RNA was isolated and analyzed by Northern analysis using an 800-basepair IL-1 beta cDNA probe. Hybridization with 32P-labeled probe showed maximal levels of IL-1 beta mRNA occurring between 3 and 7 h of culture. Cultures of lipopolysaccharide-activated human peripheral monocytes incubated for 3-6 h with increasing amounts of progesterone or estradiol (0-10(-5) M) in the presence of either 5% fetal calf serum or 0.1% BSA demonstrated an inverse relationship between IL-1 beta mRNA levels and steroid concentration. In both cases, IL-1 beta mRNA levels decreased by 80-90% as the progesterone concentration increased to 10(-5) M and by 70-90% as the estradiol concentration increased similarly. A similar 80% decrease in IL-1 beta mRNA was observed with peritoneal macrophages incubated with increasing amounts of progesterone. This reciprocal relationship between IL-1 beta mRNA and gonadal steroids may have important ramifications in reproductive biology for both embryonic implantation and fetal survival as well as for clinically relevant changes in bone mass.

Adult↗
PubMed1988

Molecular analysis of T cell receptor gamma gene expression in allo-activated splenic T cells of adult mice.

Northern analysis, hybridization in situ and cDNA sequence analysis have been used to demonstrate that the induction of T cell gamma-gene expression is a general occurrence when primary splenic T cells of adult mice are cultured in short-term mixed lymphocyte reactions (MLR). Splenic T cells from nine strains of mice examined in eleven different MLR all showed significant induction of gamma-RNA, even when the primary T cell response was to only a three amino acid mismatch in a major histocompatibility complex class I antigen. In MLR examined in detail, the expression is highly enriched for in CD3+ "double-negative" T cells (lacking both CD4 and CD8 expression). A cDNA sequence analysis, constituting the first such analysis of any size of gamma-gene transcripts from circulating, peripheral cells of adult mice, revealed transcription to be frequently of productively rearranged genes. These genes display extensive junctional diversity.

Animals↗
PubMed1988

Immune recognition and effector function in subsets of CD4 T cells.

T cells expressing the cell surface differentiation antigen CD4 are involved in most immune responses. Our studies address two issues about CD4 T cell responses to antigen: first, how does the T cell receptor come together with its ligand to generate an immune response, and what is the role of the CD4 molecule in this response? Second, are all CD4 T cells identical in their functional activity, and how does the activating signal determine the functional outcome of a response? Our studies outlined below suggest that the T cell receptor and its peptide: class II major histocompatibility complex (MHC) molecule ligand come together in a defined orientation determined in part by the binding of CD4 to both the T cell receptor and its ligand. Our studies suggest that the V beta chain is involved directly in MHC antigen recognition, binding self MHC with low affinity and non-self MHC with high affinity. The selective effect of the Mls locus on V beta expression is believed to reflect the binding of the Mls protein directly to the V beta region. CD4 is described as a co-receptor, forming an inducible part of the T cell receptor and binding to the same class II MHC molecule as that receptor. Studies with both cloned lines and normal CD4 T cell populations suggest the existence of two separable subsets with definable function. One set appears to be specialized for the activation of the humoral immune response, while the other drives the cell-mediated immune responses, particularly those involving the activation of macrophages. These two subsets of CD4 T cells have differential activation requirements, seen particularly in the requirement for interleukin 1 (IL-1) in the activation and clonal expansion of CD4 T cells involved in humoral immunity. This requirement for IL-1 may also be observed in the priming of this subset of CD4 T cells. These studies demonstrate that the optimal activation of CD4+ T cells involves recognition of peptide fragments presented by class II MHC molecules and accessory signals derived from the antigen presenting cells.

Animals↗
PubMed1987

Lymphokine synthesis is induced in human thymocytes by activation of the CD 2 (T11) pathway.

This study shows that unfractionated thymocytes can be activated to proliferate in response to activation by the CD 2 pathway, to express interleukin 2 receptors, and to synthesize interleukin 2 and interferon-gamma. Less mature, T3- thymocytes, isolated by negative selection are activated to a lesser extent than are unfractionated thymocytes; activation by the CD 2 pathway, induces proliferation, the expression of the interleukin 2 gene and interferon-gamma synthesis. 12-O-Tetradecanoyl phorbol 13-acetate in combination with the anti-CD 2 antibodies T11(2) + T11(3) increases the response of both unfractionated and T3- thymocytes. In addition we demonstrate that tetradecanoyl phorbol acetate in combination with T11(3) can replace the requirement for T11(2) for thymocyte activation and induce the expression of T11(3).

Antibodies, Monoclonal↗
PubMed1987

c-myc gene expression and activation of human thymocytes.

The relationship between c-myc expression and thymocyte activation was studied in freshly isolated human thymocytes and in thymocytes activated with various inducing agents. In freshly isolated thymocytes c-myc mRNA is expressed at low levels, while thymocytes activated with Concanavalin A (Con A), the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), Con A in combination with TPA or interleukin 2 (IL-2) are induced to express higher levels of c-myc mRNA. The expression of c-myc is increased within 3 h of stimulation with these inducing agents; the amount of c-myc mRNA which is accumulated is not correlated with the rate of thymocyte proliferation. Dexamethasone and Cyclosporin A (CsA) which inhibit early events of T cell activation and the expression of the interleukin-2 (IL-2) and gamma-interferon (gamma-IFN) genes also markedly suppress the expression of c-myc mRNA in Con A, and Con A + TPA-activated thymocytes. We conclude that activation of c-myc gene expression is an early event observed in activated human thymocytes. The level of c-myc expression is dependent on the mode of thymocyte activation rather than on the rate of thymocyte proliferation. Since freshly isolated thymocytes express low levels of c-myc mRNA it is possible that IL-2 induces c-myc expression at least in a responsive subpopulation of thymocytes during ontogeny.

Cell Transformation, Neoplastic↗
PubMed1986

Induction of interleukin 2 receptors on immature human thymocytes and co-expression of T3 and T6 antigens.

We have recently demonstrated that human thymocytes can be induced to express interleukin 2 (IL-2) receptors and to synthesize IL-2. The present study shows that relatively immature T6+ human thymocytes as well as the more mature T3+ thymocytes could be induced to express functional IL-2 receptors when activated with either Concanavalin A (Con A), Con A and 12-O-tetradecanoylphorbol 13-acetate (TPA) or IL-2 in combination with Con A or TPA. The phenotype of the common, immature thymocyte was identified by the binding of either fluorescein isothiocyanate (FITC)- or phycoerythrin (PE)-conjugated monoclonal anti-T6 (OKT 6) antibody and of mature thymocytes by the binding of monoclonal anti-T3 (OKT 3) antibody. We also observed that the expression of the T3 antigen on thymocytes, freshly isolated from thymic specimens obtained in the course of cardiac surgery of infants and children, was greater than 40% in 14 of 18 donors and that thymocytes co-expressed the T3 and the T6 antigen as determined by dual colour cytofluorometry. In thymocytes activated in vitro the expression of IL-2 receptors, determined by dual colour cytofluorometry with the PE-conjugated monoclonal anti-human IL-2 receptor antibody (PE anti-IL-2 R), was detected by the second day of induction in both immature T6+ and mature T3+ thymocytes. T6+ thymocytes proliferated in response to IL-2 and persisted in cultures for the duration of the study (18 days) and continued to express IL-2 receptors.

Antigens, Differentiation, T-Lymphocyte↗