Biomedical subjects

S Plaeger

Publications and source records attributed to S Plaeger.

21 records · Page 2Linked to original sources

PubMed1996

Impact of social confrontation on rat CD4 T cells bearing different CD45R isoforms.

The impact of social defeat on lymphocyte subpopulations and T helper subsets was investigated in Long Evans rats. CD4 T helper cell subsets with distinct functional properties and different cytokine profiles can be distinguished by using the mAbs OX-22 (anti-CD45RC) and OX-7 (anti-CD90, Thy1.1). Male intruders were exposed for 2, 6, or 48 h to aggressive resident pairs. All intruders were attacked upon introduction and were defeated as indicated by frequent display of full submissive postures. After 2 and 48 h of confrontation, drastic but differential effects on blood leukocyte numbers, CD4 and CD8a cells, and CD4 subsets were evident. However, after 6 h of confrontation most lymphocyte subset numbers corresponded to baseline levels. Focusing on CD4 subsets after 2 h of confrontation, we demonstrated that only the number of the CD45RC-CD90(-) subset declines, whereas neither the number of the CD45RC+CD90(-) subset nor the number of the CD45RC-CD90(+) subset (recent thymic emigrants) was influenced. Con A stimulation of sorted subsets identified the CD45RC-CD90(-) as a poor producer of IFN-gamma. The data clearly demonstrate that social factors might differentially influence not only T cell subsets but also T helper cell subsets with distinct cytokine profiles in a possibly time-dependent manner. Such a stress-induced shift toward a CD45RC+CD90(-)-dominated milieu may have important consequences in interpreting results obtained from mitogenic stimulation of blood lymphocytes and cytokine production profiles measured after such a stimulation. In addition, a shift toward a CD45RC+CD90(-) dominance may modify the type and magnitude of immune response, at least temporarily.

Animals↗

PubMed1996

HIV disease in children is associated with a selective decrease in CD23+ and CD62L+ B cells.

We characterized the surface phenotype of B cells from HIV+ children in order to better understand the biology of B cell dysregulation. Twenty-nine HIV-infected, twenty-one exposed, and nineteen age-matched control children were studied for expression of CD5, CD10, CD21, CD23, CD25, CD62L, CD71, and CD69. We conclude that, despite persistent high immunoglobulin levels, total B cells decreased as HIV disease progressed, with selective decreases in CD62L+ and CD23+ B cells. This resulted in an increased proportion of usually minor subpopulations of CD62L- and CD23-negative B cells. We did not find significantly altered B cell expression of other activation/immaturity antigens. This suggests an absolute decrease in a subset of antigen-responsive B cells and a disproportionate increase in a subset of hyperstimulated B cells. These findings provide a biological basis for the paradoxical generalized B cell hyperactivity and specific immune unresponsiveness that are characteristic of HIV infection in children.

Antigens, CD↗

PubMed1995

IL-6 induces target cell resistance to HIV-specific cytotoxic lysis.

Interleukin-6 (IL-6) is a pleiotropic cytokine with multiple immunomodulatory functions. Although IL-6 enhances cytotoxic effector cell function in vitro, we report the paradoxical effect of IL-6-induced resistance of target cells to lysis by cytotoxic T lymphocytes (CTL). The CTL system employed autologous, Epstein-Barr virus-transformed B lymphoblastoid target cells infected with vaccinia virus vectors carrying the envelope gene from the human immunodeficiency virus (HIV). Effector cells were fresh peripheral blood mononuclear cells from HIV+ individuals. Resistance was induced by exposing B cell line targets to exogenous IL-6, or via an autocrine pathway in which IL-6 was secreted by the target cells themselves. The IL-6 effect was dose dependent and reversible by antibody to IL-6. A large proportion of B cell lines from HIV+ individuals produced IL-6, and the lysis of HIV envelope-expressing B cell targets was inversely proportional to the amounts of IL-6 produced by the cell lines. These findings have significance for the utility and interpretation of CTL assays as in vitro correlates of T cell competence and may be significant in vivo in situations such as HIV infection where IL-6 production is increased.

Adult↗