Crystalloid inclusions in brain macrophages and hemopoietic tissue in GFAP-IL3 mice resemble inclusions identified in multiple sclerosis

Crystalloid inclusions or "pole bodies" observed in brain macrophages in hu man demyelinating disease represent a morphological enigma. Similar inclusi ons were detected in brain macrophages from the GFAP-IL3 mouse, a transgeni c murine model for macrophage mediated demyelination. Mice also showed incl usions in hematopoietic tissue. They appear to be related to phagocytosis a nd secretion, respectively, as evidenced by the fact that in phagocytosing cells they often merged with lysozomes and that affected cells showed empty channels open to the interstitium. Based on ultrastructural and immunoloca lization studies using chaperonin-10, lysozyme, and cathepsin the authors s uggest that these inclusions are consistent with phagocytosis-related secre tory products. This study may provide insight into the nature and significa nce of similar macrophage inclusions recently identified in multiple sclero sis.