Brain lesion-induced alteration of selected phenotypic properties of spleen macrophages and their partial restoration in the course of foreign body reaction against intraperitoneally implanted polymers

A lesion in the dorsoposterior part of the rat brain septum is known to exe rt an inhibitory effect on the delayed skin hypersensitivity and incorporat ion of radiolabeled thymidine into the lymphoid organs. To determine whethe r distinct properties of macrophages will also be modulated by this type of injury, we have focused upon the monitoring of expression of sugar recepto rs (lectins). In this study we show a reduction in the number of macrophage s expressing carbohydrate-binding sites for asialoglycoproteins (beta-D-gal actoside), alpha-D-mannoside and alpha-D-mannoside-6-phosphate in spleen ma crophages after the lesion of the dorsoposterior septum of the brain in the rat. The number of ED-1(+) macrophages was not influenced. The intraperito neal injection of beads prepared from the copolymer of 2-hydroxyethyl metha crylate with dimethyl aminoethyl methacrylate (30 wt %) elevated significan tly the number of ED-1(+) spleen macrophages and number of macrophages with binding site(s) recognizing asialoglycoproteins and alpha-D-mannoside-6-ph osphate, respectively. These results indicate that a foreign-body reaction appears to be able to mediate a phenotypic restoration of lectin expression by spleen macrophages altered by the brain lesion. It can be suggested tha t, for example, a probable production of cytokines by the inflammatory cell s colonizing the implanted beads plays a role in this process. (C) 1999 Klu wer Academic Publishers.