SPHINGOLIPID ACTIVATOR PROTEINS IN THE NEURONAL CEROID-LIPOFUSCINOSES- AN IMMUNOLOGICAL STUDY

The molecular defects underlying neuronal ceroid-lipofuscinoses (NCL) are still unknown. However, more data exist on the composition of the hydrophobic storage material characteristic of NCL. Accumulation of su bunit c of the mitochondrial ATP synthase has been shown in most forms of human NCL with the exception of the infantile NCL (INCL) for which we have recently demonstrated storage of sphingolipid activator prote ins (SAP). In the present study we raised an antiserum against storage cytosomes purified from INCL brain. Using the anti-INCL antiserum and monospecific SAP antisera, we studied storage material isolated from the brains of patients affected with NCL by Western analysis, and foun d a 12-kDa protein showing a SAP-like immunoreactivity not only in INC L, but also in all the childhood forms of NCL. Furthermore, using the anti-sap-D antiserum for immunohistochemistry, we observed strong immu noreactivity of the storage cytosomes in all major forms of NCL, and a lso in tissues of non-neuroectodermal origin. From these data we concl ude that the presence of SAP within the storage bodies is a phenomenon common to all major forms of human NCL.