Characterization of NK phenotype in the clinical course of MS. (a) Reduction of IL-5 mRNA during relapse. Total RNA was isolated from NK cells and then subjected to quantitative RT-PCR analysis. The data obtained from the same patients at different stages are connected with lines. (b) Decreased frequency of CD95⁺ NK cells during relapse. Freshly isolated PBMCs were stained with anti–CD3-FITC, anti–CD56-PE, and anti–CD95-biotin/Streptavidin-Cychrome and analyzed by flow fluorocytometry. The data are expressed as percentages of CD95⁺ cells among CD56⁺CD3^–-gated NK cells. ^A,BSample pair from the same patient analyzed for these two parameters. Mann-Whitney U test was used for both a and b. (c) Increase of CD95⁺ NK cells after clinical recovery. The frequency of CD95⁺ NK cells was determined as performed in b. The first samples were obtained on the day of hospitalization (relapse) before starting injection of 1,000 mg/d of methylprednisolone (steroid pulse) for 3 consecutive days. The second samples were obtained 5–7 days after the start of the pulse therapy (shortly after steroid pulse therapy). The third samples were collected 1 month after the first sampling (1 month after relapse). Bars = SE. Friedman test was used for statistical analysis.