Comparison of two molecular species of ethanolamine plasmalogen in multiple sclerosis and normal myelin

A TLC procedure which resolves two molecular species of ethanolamine plasmalogen, Pl-PE-1 and Pl-PE-2, was used to compare the ratio of these was species in myelin isolated from normal appearing white matter from brains of 17 multiple sclerosis (MS) patients, 17 normal (N) individuals, 1 patient with subacute sclerosing panencephalitis (SSPE) and 1 patient with a non-demyelinating neurological disease (OND). One of these species (Pl-PE-2) has been reported to be unique to myelin and has primarily 18:1 in both the 1 and 2 positions of glycerol. The other species (Pl-PE-1) is also present in other membranes and has primarily a saturated chain in the 1 position and a polyunsaturated chain in the 2 position. The Pl-PE-1 to Pl-PE-2 ratio was quantitated by scanning the plates with a densitometer. The ratio was similar to normal in most of the MS samples, 0.88 +/- 0.09, but was much less th an normal in 4 of the MS samples and the SSPE sample. This is attributed to increased decomposition or hydrolysis of Pl-PE-1 relative to Pl-PE-2 at some stage, either during the disease process or due to post-mortem decomposition. Although the reason for the enhanced decomposition of Pl-PE-1 is not known it suggests that Pl-PE-2 is more stable chemically. This may be related to the unique occurrence of Pl-PE-2 in myelin.