Differential expression of some proteins between pristane-treated DA and E3 rats was investigated by fluorescence activated cell sorting (FACS) or ELISA. Differential MHC class II RT1.B and Cd28 expression was investigated using FACS. Inguinal lymph node cells from three DA and E3 rats were stained with OX-6 or JJ319 and analyzed on FACSort using the BD CellQuest™ Pro Version 4.0.1 software (Becton Dickinson, Franklin Lakes, NJ, USA). In the histogram the black peak represents the negative control, the filled grey peak the DA rats, and the unfilled peak the E3 rats. The horizontal line represent the area used for calculation of the geometric mean values. In the histogram the RT1.B and Cd28 expression of the DA and E3 rats with individual values closest to the group mean value are shown. The total plasma concentration of IgG and IgE was analyzed by ELISA. Plasma samples from four DA and E3 rats were analyzed. The data are presented as DA and E3 mean values and the error bars represent the standard error of the mean.