Suppressor Cell Regulation of Cell-mediated Immune Responses in Renal Infection in Vitro Modulation of Suppressor Cell Activity

Infection-induced anergy is a frequent complication of bacterial, viral, and parsitic infection. A marked suppression of the thymus-derived (T) lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection and the mechanisms by which suppression occurs have been investigated. In particular we have considered the possibility that suppression might result from the inhibitory effect of prostaglandins, secreted by activated macrophages with immunoregulatory potential. The experiments have shown that the T-lymphocyte effector status in experimentally-induced renal infection is determined by two suppressor cells, one infection-induced and the other naturally occurring. The inability to respond to mitogenic stimulation was reversible and restoration of immune responsiveness to splenic lymphocytes from infected animals could be achieved in two stepwise manipulations; differential centrifugation removed the infection-induced suppressor cells, and the suppressor activity of the naturally occurring suppressor cells could then be inhibited by indomethacin. Thus the two suppressor cells were distinguishable on the basis of their physical characteristics and their response to indomethacin. The dominant factor determining the immune responsiveness of splenic lymphocytes from the pyelonephritic animals was, however, the infection-induced suppressor cell. This cell has been characterized as a sedimentable cell (30 g) with suppressor activity demonstrable in co-culture experiments. Plastic-adherent cells from the sedimentable fraction of pyelonephritic animals' splenic cells were shown to have suppressor activity that was not inhibited by indomethacin. The infection-induced and naturally occurring suppressor cells can be viewed as prototypes for the equivalent cells in man and may be useful models for studying the role of these cells as determinants in the pathogenesis of infectious disease.