Enhancement of human natural killer cells by interferon requires RNA and protein synthesis

An enriched population of human natural killer (NK) cells was obtained by density gradient centrifugation. The cytotoxic activity of these cells was enhanced by pretreatment with human leukocyte interferon (IF), and the metabolic requirements of this enhancement were examined. Augmentation of NK activity was initiated in a rapid, temperature-independent manner, requiring only a 10- to 15-min exposure to IF, and occurred at either 4 or 37[deg]C. Increased activity of the IF-treated NK effector cells was consistently observed after only 30 min of contact with target cells. Augmentation was inhibited by prior treatment of NK effector cells with actinomycin D (AD), but treatment with AD after 1 hr of IF treatment did not inhibit the IF-mediated increase in cytotoxicity, suggesting that the RNA species required for enhancement are synthesized within 1 hr of cell-IF interaction. Protein synthesis was required for at least 1 hr following cell-IF interaction, as shown by the ability of emetine and puromycin treatments to abrogate increased NK cell activity. Binding of IF to cells was independent of protein synthesis. IF-induced enhancement was unaffected by incubation of effector cells with mitomycin C either before or after IF treatment, indicating that IF acts primarily upon a population of preexisting cells of lower NK activity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23787/1/0000025.pd

Characterization of Human Natural Killer Activity Against Target Cells Infected with Herpes Simplex Virus Type 1.

Little is known about target cell membrane structures recognized by natural killer (NK) cells. The purpose of these studies was to define the NK recognition structures on herpes simplex virus type 1 (HSV-1) infected cells. The approach involved altering the viral antigenic components presented on the infected cell membrane using a glycosylation inhibitor in combination with antigenically deficient or antigenically altered virus mutants. NK activity against infected target cells lacking cell surface HSV-1 glycoprotein B (gB) or C (gC) were (TURN) 30% less sensitive to NK activity than targets infected with wild-type HSV-1. An (TURN) 60% decrease in activity was seen against targets lacking both cell membrane gB and gC. Differences in susceptibility of infected targets were paralleled by differences in ability to bind NK effector cells. The NK activity seen against a given infected target did not correlate with the amount of interferon generated, and reduction in the amount of interferon present by anti-IFN antibody or pretreatment of effectors with an RNA synthesis inhibitor had no effect on cytotoxicity against HSV-1 infected targets. NK activity against these targets was shown to be independent of interferon induction. The fine specificity of NK recognition of HSV-1 glycoproteins was further explored by demonstrating that monoclonal antibody Fab fragments specific for either gB or gC blocked NK activity against HSV-1 infected targets. In addition, cells infected with antigenic variants of HSV-1, selected with virus-neutralizing monoclonal antibodies, were shown to have altered susceptibility to NK recognition and killing. These data indicated that alterations in viral glycoprotein epitopes affect NK-target cell interaction, providing the first evidence that antigenic variation can reduce susceptibility of target cells to NK activity. Together these studies demonstrated a molecular basis for NK cell recognition of HSV-1 infected target cells and further suggest the existence of clones of NK cells with a high degree of target specificity.Ph.D.MicrobiologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159704/1/8402243.pd