[A case of measles meningoencephalitis with marked increase of plasma cells in cerebrospinal fluid].

Marked increase of plasma cells in cerebrospinal fluid (CSF) was observed in a 22-year-old female patient with measles meningoencephalitis. Typical measles exanthema was followed, 3 days later, by neurological abnormalities such as confusion, severe meningeal signs and bilateral pyramidal signs. Immunological examination showed slight elevation of IgG, normal T cell subsets and NK cell activity in peripheral blood. The antibody titer of measles was 32x in serum (4x after 2 months). CSF contained 167 cells/mm3, 66% of which was plasma cells. Total protein was 75 mg/dl, and IgG (24.5 mg/dl) showed high values. The antibody titer of measles was 4x (1x after 2 months). The antibody index was 7.15 (N = 2). The anti-myelin antibody was 8x. Oligoclonal band in CSF was negative. The appearance of large number of plasma cells in CSF in viral meningoencephalitis is extremely rare in the literature. However, B cell activation in peripheral blood in measles encephalitis has been reported. Therefore, immunologically abnormal findings in CSF of this case suggest marked B cell activation occurring in the central nervous system in measles meningoencephalitis.