Which of the following statements best characterizes natural killer cells?

Natural killer (NK) cells account for 5% to 10% of lymphocytes. They paicipate in antibody dependent cellular cytotoxicity reactions (type II hypersensitivity reactions). NK cells are not T cells and are sometimes referred to as null cells. They can lyse virally infected cells and tumor cells without prior sensitization. NK cells are frequently referred to as large granular lymphocytes, and would not be confused with small B cells. When activated by interleukin-l, NK cells become lymphocyte-activated killer cells (LAK cells), which can be used to treat ceain cancers. NK cells are a source of gamma interferon, which induces class II expression and activates macroptIages.