Type B Niemann-Pick disease (
NPD) is a nonneuronopathic lysosomal storage disorder which is characterized by accumulation of
sphingomyelin-laden macrophages. The availability of plasma markers for storage cells may be of great value in facilitating therapeutic decisions. Given the similarity of the storage cells in
NPD and
Gaucher disease, we studied Gaucher plasma markers (
chitotriosidase and CCL18) in two siblings homozygous for the R228C mutation in
acid sphingomyelinase (ASM) and a type B course of
NPD. The older sibling, first examined at the age of 9 months, showed marked hepatosplenomegaly and pulmonary involvement. The younger sibling has mild asymptomatic hepatosplenomgaly at the age of 5 months. Analysis of plasma specimens revealed markedly increased levels of
chitotriosidase and CCL18 in the older sibling. In the younger child also, plasma
chitotriosidase and CCL18 were clearly elevated above normal values almost immediately after birth and rapidly increased further. Histochemistry confirmed production of CCL18 by foam cells. In conclusion, plasma
chitotriosidase and CCL18 may also serve as markers for the formation of pathological
lipid-laden macrophages in type B
NPD, in analogy to
Gaucher disease. The availability of sensitive plasma
surrogate markers may be of great value for monitoring the efficacy of
enzyme supplementation
therapy that is currently being developed.