Giant lysosomes, a cytoplasmic marker in osteoclasts of beige mice

The beige mouse (bg/bg) is an analogue of the Chediak-Higashi syndrome (CHS) in man. The disorder is characterised by the presence of enlarged cytoplasmic granules, said to be lysosomes, in many cell types. The present report describes giant lysosomes defined as lysosomes greater than 1.0 micrometers in diameter, in osteoclasts of beige mice. The giant lysosomes contained both acid phosphatase and aryl sulphatase and were present in osteoclasts of beige mice aged from at least 4 days to 3 months. There is some evidence that the giant lysosomes form by fusion of smaller structures. Since giant lysosomes were also seen in osteoclasts from mouse strains not suffering from CHS, e.g., CBA mice, a quantitative survey was carried out. It was shown that osteoclasts from beige mice aged from 4 days to 3 months contain significantly increased numbers of giant lysosomes when compared with osteoclasts from CBA mice and CBAXbg/bg F1 hybrids. The giant lysosomes of the beige mouse osteoclast are currently being used as cytoplasmic markers in experiments on the cell of origin of the osteoclast.