Malarial immunodepression in vitro: adherent spleen cells are functionally defective as accessory cells in the response to horse erythrocytes.

The basis for the depressed response of malarial infected mice to horse red blood cells (HRBC) has been studied in vitro. Results presented show that the adherent spleen cells from infected mice (a) are defective in their ability to allow nonadherent spleen cells of both normal and infected mice to respond to HRBC whereas a response does occur with adherent spleen cells from normal mice (b) do not suppress the response of unfractionated spleen cells from normal mice to HRBC (c) contain phagocytic cells as measured by the uptake of neutral red in numbers which are of the same order of magnitude as in adherent spleen cells from normal mice, but which are unable to take up HRBC. We conclude that a splenic adherent cell, probably the macrophage is functionally defective as an accessory cell in the response to HRBC of mice infected with Plasmodium berghei yoelii.