Gamma interferon-like immunoreactivity in the rat nervous system

The presence of gamma interferon-like immunoreactivity in the peripheral nervous system and in some central nervous system neurons is described. The immunohistochemical evidence is based upon labeling of neurons with five different monoclonal antibodies against rat gamma interferon and one polyclonal antiserum. Immunoreactive material was abundantly present in the peripheral nervous system including small primary sensory neurons in dorsal root ganglia and postsynaptic neurons of the sympathetic and parasympathetic nervous system. Large neurons in dorsal root ganglia were not stained. Neurites stained with DB1 antibody against rat gamma interferon were found in most organs examined such as the gastrointestinal tract, heart, lungs, kidney, sexual organs and skin. In contrast, staining was weak in the central nervous system and restricted to a few neurons in the hypothalamus and in the midbrain. It is speculated that this newly discovered system containing a gamma interferon-like neuropeptide could be involved in the neuronal control of immunological processes in its target organs.