We studied the immunologic molecules in cerebrospinal fluid (CSF) and discussed their evolutional changes in pediatric patients with Rasmussen syndrome (RS). CSF samples collected from 27 patients with RS (average onset age, 7.5 +/- 5.6 years) were studied. Cell count, protein, glucose, albumin, chloride, and immunoglobulin G (IgG) levels were measured by conventional methods. Surface markers of lymphocytes in CSF were examined by a cell sorter. Granzyme B, interferon gamma (IFNgamma), interleukin 4 (IL-4), tumor necrosis factor alpha (TNFalpha), and IL-12 in CSF were quantitated by enzyme-linked immunosorbent assay (ELISA). Autoantibodies against GluR epsilon2 (NR2B) were examined by immunoblot. The data of the first CSF examination showed that IgG levels (Mann-Whitney U test, p < 0.01), CD4(+) T cells (p = 0.02), TNFalpha levels (p < 0.01), and Granzyme B levels (p < 0.01) were elevated compared with disease controls. White blood cell count, IFNgamma level, IL-12 level, and Granzyme B level were elevated, especially in the early stage of disease. CD4(+) T cells, CD8(+) cells, CD3(+) T cells, IgG levels, and TNFalpha levels were elevated at all stages of disease evolution. Protein levels and albumin levels were elevated in the progressed stage. Autoantibodies against GluR epsilon2 (NR2B) (IgG) were found in 50% of patients in the early stage, and the positive rate was low at the progressed stage. The present findings suggest that complex pathophysiologic mechanisms involving CD4(+) T cells and CD8(+) T cells change evolutionally during the progression of RS. A crucial cytotoxic process occurs in the early stage, and declines in the progressed stage.