A macrophage immunosuppression induced by Leishmania major in BALB/c mice.

The purpose of the present study is to investigate the status of the reticuloendothelial system (RES) phagocytic function in relation to Leishmania major infection in highly susceptible BALB/c mice. The RES phagocytosis was monitored by: intravascular clearance of carbon colloid; tissue distribution 99mTechnetium labelled sulphur colloid in RES organs; and serum lysozyme enzyme level. The kinetics of RES phagocytosis during L. major infection was also studied at 0, 3, 5, 7 and 8 weeks post-infection. The results revealed that L. major parasite significantly (p less than 0.001) inhibited macrophage phagocytic function. The maximum phagocyte depression was noticed at 7 weeks following infection. The macrophage phagocytic suppression was also associated with a reduction in liver and spleen uptake of 99mTc and decrease in serum lysozyme level.