Clinical significance of natural killing activity in patients with advanced lymphoma.

Using a newly described analysis of natural killing activity employing an "individual effector/target cell ratio" according to the number of effector cells in blood, we recently determined that patients with spontaneous lymphoma regression had elevated natural killing activity prior to regression. To clarify the clinical significance of natural killing activity in patients with advanced lymphoma, a prospective study was performed at a single institution in 43 untreated patients. Survival was analyzed to detect prognostic variables. Among factors chosen initially by univariate analyses, multivariate analysis selected three prognostic factors: chemotherapy response (P < 0.0001), low-grade lymphoma (P = 0.0005), and natural killing activity (P = 0.0052). Within the chemotherapy response, natural killing activity was a unique correlative factor (P < 0.0001) selected by a multivariate regression analysis using forward selection method. In patients with advanced lymphoma, natural killing activity is a valuable prognostic factor and may also predict the response to chemotherapy.