Immune system -function assessed in term of antibody responsiveness, macrophages and natural killer (NK) cell function. Towcytometric analysis of T cell lymphocytes in spleen and cecal tonsils of three weeks old birds were determined after infection with 1x104 oocyst of E. maxima per bird ai i challenged 3 weeks later with 5x1 03 oocysts of E. / axitna. TK birds showed high percentage of CD4 T c ?lls in spleerf culture at 1,2, and 21 days post infection wh e SC birds showed low percentage of these cells. SC bird showed high percentage of CDS T cells and 35% of B ;ells while TK birds showed about 25% of these cells in s ileen culture, while it become 60% in SC, it was 35% ir TK birds in cecal culture at the 4th day post infection