Observations on leukocytes from patients with severe familial hypercholesterolemia.

Differences in light scatter and fluorescence emission of blood leukocytes from patients with familial hypercholesterolemia (FH) and normal patients incubated with oil red O and r(NBD-Cl)-acetyl-LDL were observed by flow-through cytofluorometry and used to distinguish a subclass of leukocytes. The appearance of this subpopulation of leukocytes in FH apparently correlated with the excessive hypercholesterolemia. In addition, microscopic evaluation of blood smears suggested the formation of small cytoplasmic vacuoles in a population of FH monocytic cells. While these are preliminary observations on a small number of patients, they warrant further study. However, the use of lipophilic dyes and fluorescent acetyl-LDL in combination with flow cytometry may be another useful means for evaluation of FH.