The inflammatory reaction of paraneoplastic ganglionitis and encephalitis: an immunohistochemical study.

To elucidate the cellular mechanisms of tissue injury in paraneoplastic states, tissues from two patients with small cell carcinoma of the lung and paraneoplastic neurological syndromes were studied. One patient had encephalitis with ganglionitis, and the other ganglionitis. Immunocytochemistry on brain and ganglia was performed using monoclonal and polyclonal antibodies. The majority of the inflammatory cells in brain and ganglia were T-cells, of both helper and cytotoxic subtypes. There were more macrophages in the inflammatory infiltrate of ganglia than in the brain of encephalitis. Major histocompatibility complex class I and II antigen expression was greater in the mononuclear cells in brain than in ganglia. There was no evidence of complement deposition and little evidence for antibody synthesizing cells. Our findings suggest a T-cell-mediated immune attack in paraneoplastic ganglionitis and encephalitis, with a greater role for macrophages in ganglionitis.