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  • Title: Generation of IL-2-dependent cytolytic T lymphocytes (CTLs) with altered TCR responses derived from antigen-dependent CTL clones.
    Author: Gullo CA, Esser MT, Fuller CL, Lam Braciale V.
    Journal: J Immunol; 1999 Jun 01; 162(11):6466-72. PubMed ID: 10352261.
    Abstract:
    Ag-specific CD8+ CTL clones require TCR stimulation to respond to IL-2 for growth. Because IL-2 may be produced in the vicinity of CD8+ CTLs when Ag is limiting at the end of an immune response, we have examined the effect of culturing viral-specific CTL clones in IL-2 in the absence of antigenic stimulation. Limiting dilution analysis revealed a high precursor frequency for CTL clones derived from IL-2 propagation (termed CTL-factor dependent (FD)) that are dependent upon exogenous IL-2 for growth and survival and no longer require TCR stimulation to proliferate. Culturing CTL-FDs with infected splenocytes presenting Ag and IL-2 did not revert the clones but did lead to a TCR-induced inhibition of proliferation. The derived CTL-FDs have lost the ability to kill via the perforin/granule exocytosis mechanism of killing, although they express similar levels of TCR, CD3epsilon, CD8alphabeta, CD45, and LFA-1 compared with the parental clones. The CTL-FDs retain Fas ligand/Fas-mediated cytotoxicity, and IFN-gamma production and regulate the expression of CD69 and IL-2Ralpha when triggered through the TCR. A parental CTL protected BALB/c mice from a lethal challenge of influenza virus, whereas a CTL-FD did not. These findings represent a novel regulatory function of IL-2 in vitro that, if functional in vivo, may serve to down-regulate cellular immune responses.
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