Sensitization of resting T cells to autologous natural-killer-cell- mediated lysis by phytohemagglutinin

Lea Baraz, Moshe Kotler, Reba Condiotti, Arnon Nagler

Research output: Contribution to journalArticlepeer-review


Natural killer (NK) cells are non-T, non-B cell lymphocytes that lyse a variety of tumor and virus-infected cells. In this study, we demonstrated that phytohemagglutinin (PHA) rendered resistant autologous T cells extremely sensitive to natural-killer(NK)-cell-mediated lysis. The sensitization was very rapid and concentration-dependent (0.01-1 μg/ml); 62% and 95% of autologous T cells were lysed by interleukin-2-activated N K cells 5 min and 18 h respectively after treatment with PHA (1 μg/ml). The maximal decrease in the level of MHC class I molecules observed on T cells was 22%. Induction of susceptibility to NK-mediated lysis was correlated with the expression of activation markers on T cells treated for relatively long intervals (more than 18 h) with high concentrations of PHA (more than 0.1 μg/ml). Sensitization of T cells required RNA and protein synthesis, although DNA synthesis was not essential. We propose that this unique system is suitable for studying the mechanisms involved in recognition and killing of target cells by NK cells.

Original languageEnglish
Pages (from-to)507-516
Number of pages10
JournalCancer Immunology, Immunotherapy
Issue number9
StatePublished - 1999
Externally publishedYes


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