CD40LG and immune system disorder: In this study, the titer of anti-Toxoplasma IgM antibody in patients with thalassemia major (3.4%), was almost compatible with the results of study in immunodeficiency and hemodialysis patients 2.3%, (21) and contradicted in neoplasia patients 6.5% (16), in cancer patients 10.3% (19), in blood donors 0.28% (22), and with those of (23) in kidney disease patients, 6.7%.