Distribution of Thy-1 in the avian nervous system: immunohistochemical and absorption analyses with a monoclonal antibody.

A monoclonal antibody against chicken Thy-1 has been used to study the histochemical localisation of Thy-1 in chicken nervous and lymphoid tissues and to quantitate the relative amounts of Thy-1 in different brain subregions, subcellular fractions and non-neural tissues. An indirect ELISA using chicken brain membranes as a target established that the highest levels of Thy-1 were present in chicken forebrain, followed by midbrain, brainstem, spinal cord, cerebellum, retina and sciatic nerve. Analyses of subcellular fractions of chicken forebrain revealed a generalised localisation of Thy-1 on membranes comprising both the junctional and extrajunctional components of the synaptosome. Consistent with this finding are the immunohistochemical studies on cryostat sections where Thy-1 was localised to certain axonal and synaptic regions of chicken nervous tissue. Strong monoclonal antibody binding was found in the molecular layer and white matter of chicken cerebellar sections with fibrous staining on the axons running through the granule cell layer. No continuous staining could be seen on the perikaryal membranes of Purkinje cells or granule cells and no staining was present within the cell bodies. The Bergmann glia of the cerebellum were Thy-1-negative. The monoclonal antibody showed preferential binding to the inner plexiform and optic fibre layers of the chicken retina, suggesting a retinal ganglion cell localisation for chicken Thy-1, as has been suggested for the rat and mouse homologues. Surprisingly the lymphocytes of both the bursa and thymus gland were Thy-1-negative, however some extracellular staining was observed of interlobular connective tissue of the bursa.