Intraneuronal IgG in the central nervous system.

The rat central nervous system was examined immunocytochemically for the presence of endogenous IgG. Examination of representative sections of the neuraxis revealed specific staining for IgG in the pia mater and pial vasculature, the ependyma, and diffusely in the hypothalamus and area postrema where the blood-brain barrier is permeable to large molecules. In addition, intraneuronal staining for IgG was noted in specific nuclei including the ventral horn nuclei and intermediolateral nuclei of the spinal cord, the dorsal motor nucleus of the vagus, the nucleus ambiguous, the motor nucleus of the trigeminal, the hypoglossal, facial, and oculomotor nuclei, nuclei projecting to the pituitary and area postrema, and Purkinje cells. The uptake of immunoglobins by these cell groups may have important implications for the pathogenesis of motor and autonomic neuropathies and neuropathies.