Relationship between natural killer (NK) activity and eosinophil, neutrophil and lymphocyte level in human blood.

Natural Killer (NK) activity by blood lymphocytes from healthy males was determined in 4-h-51Cr release assay with K562 target cells. Individuals with a high ratio of neutrophils to lymphocytes had a significantly lower NK activity compared with that of those with a low ratio of neutrophils to lymphocytes. On the other hand, no correlation of NK activity with absolute lymphocyte count was observed. Eosinophilia in blood was found to be accompanied by increased NK activity. Some biological aspects of these interdependences are discussed.