EN
The immunity in Toxoplasma gondii infections The article presents selected data concerning pathogenesis, clinical manifestations, natural and specific resistance and vaccines against T. gondii infections. Toxoplasma gondii protozoan has been recognized as one of the most successful parasites infecting any nucleated cell of human individuals and most warm-blooded animals. The infection causes life-threatening disease in individuals with defective immunity such as fetuses, AIDS patients and transplant recipients. In immunocompetent humans toxoplasmosis is usually asymptomatic. Following an acute phase of infection characterized by systemic spread of rapidly dividing tachyzoites, bradyzoites encyst in various host tissues (brain, muscles) and may persist there lifelong. Toxoplasmosis in controlled by vigorous cell-mediated immune response capable of killing infected cells and parasites. As shown in the mouse experimental model natural killer cells (NK) are critical for the resistance at the early stage of primary infections, whereas adaptive immunity depends on T lymphocytes. Both CD4+ Th1 and CD8+ Tc1 lymphocytes are believed to mediate protection by producing of IFN-?, a pitoval cytokine that induces anti-Toxoplasma effector mechanisms in macrophages.