Sulphated glycosaminoglycans in guinea pig eosinophils studied by means ofcationic colloidal gold

Using bone marrow embedded in hydrophilic resin Lowicryl K4M and cationic c olloidal gold pH 1.0 labelling, we studied sites of sulphation and sulphate d glycosaminoglycans ultrastructurally in various maturational stages of bo th eosinophil granulocytes and eosinophil granules of guinea pig. Eosinophi l granules reacted positively to cationic gold, the pattern of labelling va rying according to the degree of cell maturation. The formation of eosinoph il granules takes place throughout the myelocyte stage. Early eosinophil my elocytes contain a large Golgi apparatus with active granulogenesis, while late ones contain a small and less active Golgi apparatus. All the immature granules were labelled positively. However, mature granules with a central crystal bar lost their affinity towards colloidal gold. Interestingly, str ong colloidal gold labelling was also observed in the trans to transmost Go lgi apparatus, especially in immature eosinophil granulocytes. This indicat es that sulphation of glycosaminoglycans occurs in the trans to transmost G olgi apparatus of eosinophil granulocytes. Prior absorption with poly-L-lys ine prevented colloidal gold labelling of tissue sections. Methylation of s ections at 37 degrees C did not alter the gold labelling, whereas the label ling disappeared after methylation at 60 degrees C. Prior treatment with ch ondroitinase ABC or heparinase I abolished the majority of colloidal gold l abelling in immature eosinophil granules. Taking these results together, we conclude that immature eosinophil granules contain sulphated glycosaminogl ycans including chondroitin sulphate or heparan sulphate or both. (C) 1998 Chapman & Hall.