Giant organelles containing tubules in Chediak-Higashi lymphocytes.

A giant inclusion filled with structures resembling microtubules was observed in the cytoplasm of a small percentage of circulating lymphocytes from 4 children with the Chediak-Higashi syndrome (CHS). The organelles were similar in many respects to tubule-containing inclusions described previously in normal and abnormal lymphocytes. Tubule-filled organelles appear to develop by cytoplasmic sequestration, and their massive size in CHS cells may result from fusion of small organelles to form a single giant inclusion. Acid phosphatase was found only in giant tubular inclusions which had fused with lysosomal granules. The basis for the existence of these organelles in normal and abnormal lymphocytes remains obscure.