Abstract: Dynamic changes of percentage of T cell，interleukin-2(IL-2) activity and proliferative response of T and B lymphocytes to concanavalin A(ConA) or phorble myristate acetate(PMA) in immune organs of 14dayold chickens primary infected with E. necatrix were studied by using acid nonspecific α naphthyl acetate esterase(ANAE), cellular culture technique and ［3-(4,5-dimethylthiazol-2-yl)］-2,5-diphenyltetrazolium bromide (MTT) method. The results showed that the IL-2 activity in thymus and spleen of chickens primary infected with E.necatrix was significantly increased compared with that of control, respectively, at day 16-18 and 18-21 post primary infection (PPI); The proliferative responses of T lymphocytes to ConA in thymus and spleen of chickens infected with E. necatrix were significantly elevated compared with that of control chickens at day 14-16 and 10-18 PPI, respectively. The proliferative responses of B lymphocytes to PMA in spleen and bursa of Fabricius of chickens infected with E. necatrix were significantly higher than that of control at 14-21 and 14-24 PPI, respectively. These results showed that IL-2 immune regulation and function of cellular immune and fluid immune in immune organs of chickens primary infected with E. necatrix had significantly increased.