Platelet microtubules and giant granules in the Chediak-Higashi syndrome.

Platelets from a child with the characteristic clinical and laboratory features of the Chediak-Higashi Syndrome (CHS) were evaluated in the electron microscope. Rare peripheral blood platelets were found to contain the giant abnormal granules observed previously in nearly all leukocytes. The discoid CHS platelets contained circumferential bundles of microtubules identical to those present in normal cells. CHS platelet microtubules responded in the same manner as those in normal cells when patient platelets were exposed to collagen, cold, or to chilling and rewarming. The findings are inconsistent with the concept that a defect in microtubule assembly is the fundamental abnormality responsible for aberrent function of CHS cells.