A suppressor B lymphocyte inhibiting IL-2 consumption in spleen cell cultures from Mycobacterium bovis BCG-infected mice

Abstract

In concanavalin A (Con A)-activated spleen cell (SC) cultures from normal C57BL/6 mice, the production of IL-2 peaked at 18-20 hr after initiation of cultures and declined rapidly during the next 24 hr, the decline of IL-2 activity being due, at least in part, to its utilization by the Con A-induced IL-2 receptor cells. In Con A-activated SC from BCG-infected mice, significant levels of IL-2 activity persisted in the 48-hr and 72-hr culture supernatants, a situation which seemed to be related to the depressed capacity of infected splenocytes to acquire IL-2 receptors. In cell mixing experiments, SC from infected mice actively depressed the utilization of IL-2 by Con A-activated normal SC, thus indicating that suppressor cells can down-regulate IL-2 responsiveness. These suppressor cells may belong to the B-cell lineage since they possessed the Thy-1-, sIg+ and FcR+ phenotype.