Effects of Paragonims westermani infection were observed in mice on the change of serum IgE level, the number of peripheral eosinophils and the distribution of Thy 1.2+ (CD3), L3T4+ (CD4), and Lyt-2+ (CD8) splenic T lymphocytes without mitogen stimulation. BALB/c mice were infected with 20 metacercariae of P. westermani each. Total serum IgE increased at 3 weeks after the infection and reached a peak on week 4 and maintained high levels of IgE until the 23rd week. Peripheral eosinophil numbers increased at the second week and attained peak level on week 9. The frequency of L3T4+ (CD4) and Lyt-2+ (CD8) T lymphocytes decreased slightly until 4 weeks after the infection, but not significantly. Absolute number of L3T4+ and Lyt-2+ T lymphocytes, and the ratio of L3T4/Lyt-2 were not markedly changed over the period of observation. The frequency of Thy 1.2+ (CD3) T lymphocytes in the infected group slightly decreased until 4 weeks after the infection and showed significant reductions at the 2nd and 4th week of the infection (p < 0.05).
