Search

The Kell blood group is constituted by two covalently linked antigens at the surface of red blood cells, Kell and Kx. Whereas Kell is a metalloprotease with demonstrated in vitro enzymatic activity, the role of Kx thereon, and/or alone, remains unknown, although its absence is linked to the McLeod syndrome, a neuroacanthocytosis. In the central nervous system, the expression of Kell and XK has been suggested, but their expression patterns remain uncharacterized, as are the post-translational pathogenic mechanisms involved in the development of the McLeod syndrome. The distributions of Kell and XK were thus studied by in situ hybridization as well as immunohistochemistry in rodent and human brain. The results reveal an independent localization of the two constituents of the Kell blood group, XK (Kx) being expressed throughout this tissue, whereas Kell expression is restricted to red blood cells in cerebral vessels. The XK protein is shown to be neuronal, located mainly in intracellular compartments, suggesting a cell specific trafficking pattern, possibly associated with specific physiological functions.

In this study we analyzed the electrophysiological and clinical effects of selective removal of the forebrain noradrenergic projection from the locus coeruleus, induced by bilateral injections of 6-hydroxydopamine into the dorsal tegmental bundle on focal cobalt-induced epilepsy. Noradrenaline depletion caused a marked potentiation of the epilepsy by increasing the duration and intensity of both the clinical and electrophysiological epileptic parameters: epileptic discharges and myoclonic jerks started earlier; spiking and clinical activity were facilitated; duration of the epileptic syndrome was prolonged. On the basis of the present and previous results it is proposed that the ascending noradrenergic system plays a modulatory role on the spread of paroxysmal activities and on the severity of cobalt-induced epilepsy.