Expression of ciliary neurotrophic factor is maintained in spinal motor neurons of amyotrophic lateral sclerosis

Ciliary neurotrophic factor (CNTF) was originally identified as a potent survival factor for a variety of neuronal cell types in vitro and in vivo and in particular in spinal motor neurons of embryonic chick and rat. Using a monoclonal antibody against CNTF (clone 4-68) we analysed the expression of CNTF in paraffin sections of seven human brains and spinal cords immunocytochemically using the ABC method and compared these results with sections of the spinal cords of patients suffering from amyotrophic lateral sclerosis (ALS). In normal human tissue of the central nervous system CNTF immunoreactivity was found in most of the motor neurons of the motor cortex and ventral horn, neurons of the nucleus oculomotorius, intermediolateralis, thoracicus, ependymal cells as well as in smooth muscle cells and endothelial cells of small arteries. A reduced number of astrocytes showed a positive immunocytochemical reaction. In peripheral nerves and nerve roots of the spinal cord we also found a positive staining of Schwann cells and some axons. These immunoreactions could be confirmed by Western blot analyses. Next we analysed postmortem paraffin sections of the spinal cord of seven patients suffering from ALS (age range 30-76 years, female/male = 4:3). We found CNTF immunoreactivity in most of the motor neurons of the ventral horn in 5 cases. In two cases the number of positively stained motor neurons was less. From these results we conclude that CNTF is expressed in a high number of upper and lower motor neurons in the human CNS and that its expression is maintained in ALS patients.