Large granules and lysosomal fusion in human Chediak-Higashi white blood cells.

The phenomenon of giant anomalous lysosome formation in human Chediak-Higashi syndrome leukocytes was analyzed. Ultrastructure findings combined with cytochemical procedures for visualizing acid phosphatase and peroxidase activity showed giant anomalous granules in addition to normal, small and enlarged granules. Massive granules in lymphocytes had an appearance and structure different from those found in other leukocytes. The giant granules seem to be a product of an active fusion between primary and secondary normal sized or enlarged lysosomes. This fusion occurs in polymorphonuclear neutrophils, eosinophils and in monocytes. No fusion was found in lymphocyte granules.