A new analysis of natural killing activity and the role of monocytes in normal subjects.

A new analysis of natural killing activity in peripheral blood is proposed. In this new analysis, we did not use a fixed E/T ratio, which is practised in the conventional analysis. We employed the individual effector/target cell ratio (E/T ratio) according to the number of effector cells in the peripheral blood: the individual E/T ratio of the person was set precisely at the point when the effectors in 1 ml of the person's peripheral blood encountered 2 x 10(4) of target cells. Asymptomatic healthy persons were divided into high activity and low activity groups. Comparison between mononuclear and non-adherent cells in terms of natural killing activity indicated that monocytes possessed a suppressive effect on the activity. In the asymptomatic low activity group, monocytes were more strongly suppressive as the natural killing activity of non-adherent cells became higher. The degree of this suppression was controlled by the change in the ratio of monocytes over large granular lymphocytes (Mo/LGL ratio). The asymptomatic high activity group showed the same suppressive pattern as patients with common cold syndrome, who were found to be in an activated state of natural killing activity. In an activated state, the monocyte suppression was to a lesser degree although the natural killing activity was higher than that in a non-activated state. Also in an activated state, the degree of the suppression was controlled by the Mo/LGL ratio. In addition, the degree of monocyte suppressive function as determined by one Mo/LGL ratio was almost identical both in an activated state and in a non-activated state of natural killing activity.(ABSTRACT TRUNCATED AT 250 WORDS)