A highly sensitive whole blood natural killer cell assay

The assessment of natural killer cell activity at baseline and the monitoring of this activity during treatment is important in many diseases especially in patients with cancer and AIDS. An optimised and standardised whole blood chromium release assay is described using K562 cells, the standard target erythroleukaemic cell line. The tumour cell lysis observed using whole blood is comparable to that obtained with the standard 4 h lysis assay using peripheral blood mononuclear cells as effector cells. Results with the whole blood assay are reproducible when the incubation with K562 cells is performed over a period of 18 h. The assay necessitates only 0.6 ml of blood collected in 10 IU/ml of sodium heparin as the anticoagulant. In this report, depletion experiments, also standardised using whole blood, show that the effector cells in the whole blood assay are contained within the CD56 + cell population. This assay will be of interest where the immunological status of patients with different diseases need to be frequently monitored.