Leukocyte-derived microparticles and scanning electron microscopic structures in two fractions of fresh cerebrospinal fluid in amyotrophic lateral sclerosis: a case report

Amyotrophic lateral sclerosis is a progressive neurodegenerative disorder characterized by degeneration of motoneuron cells in anterior spinal horns. There is a need for early and accurate diagnosis with this condition. In this case report we used two complementary methods: scanning electron microscopy and fluorescence-activated cell sorting. This is the first report to our knowledge of microparticles in the cerebrospinal fluid of a patient with amyotrophic lateral sclerosis.

An 80-year-old Swedish man of Caucasian ethnicity presented to our facility with symptoms of amyotrophic lateral sclerosis starting a year before his first hospital examination, such as muscle weakness and twitching in his right hand progressing to arms, body and leg muscles. Electromyography showed classical neurophysiological findings of amyotrophic lateral sclerosis. Routine blood sample results were normal. A lumbar puncture was performed as a routine investigation and his cerebrospinal fluid was normal with regard to cell count and protein levels, and there were no signs of inflammation. However, scanning electron microscopy and fluorescence-activated cell sorting showed pronounced abnormalities compared to healthy controls. Flow cytometry analysis of two fractions of cerebrospinal fluid from our patient with amyotrophic lateral sclerosis was used to measure the specific binding of antibodies to CD42a, CD144 and CD45, and of phosphatidylserine to lactadherin. Our patient displayed over 100 times more phosphatidylserine-positive microparticles and over 400 times more cell-derived microparticles of leukocyte origin in his cerebrospinal fluid compared to healthy control subjects. The first cerebrospinal fluid fraction contained about 50% more microparticles than the second fraction. The scanning electron microscopy filters used with cerebrospinal fluid from our patient were filled with compact aggregates of spherical particles of lipid appearance, sticking together in a viscous batter. The quantitative increase in scanning electron microscopy findings corresponded to the flow cytometry result of an increase in leukocyte-derived microparticles.

Microparticles represent subcellular arrangements that can influence the pathogenesis of amyotrophic lateral sclerosis and may serve as biomarkers for underlying cellular disturbances. The increased number of leukocyte-derived microparticles with normal cell counts in cerebrospinal fluid may contribute to the amyotrophic lateral sclerosis inflammatory process by formation of immune complexes of prion-like propagation, possibly due to misfolded proteins. The two complementary methods used in this report may be additional tools for revealing the etiology of amyotrophic lateral sclerosis, for early diagnostic purposes and for evaluation of clinical trials, long-term follow-up studies and elucidating the pathophysiology in amyotrophic lateral sclerosis.