Oxidative stress and immune-suppression in Toxoplasma gondii positive blood donors: implications for safe blood transfusion.

The sero-markers of Toxoplasma gondii and oxidative stress (OS) were determined in a group of 260 blood donors attending blood banks in Greater Cairo. Twenty-four blood donors with the highest anti-T. gondii IgG titre were tested for IgG avidity. Of whom 4 (16.6%) had low IgG avidity antibodies, documenting recent infection, 6 (25%) had borderline avidity and 14 (58.3%) showed high avidity, ruling out recent infection. The plasma level of malondialdehyde (MDA) was significantly higher and activity of glutathione peroxidase (GSH-Px) and level of tocopherol (alpha, gamma, & lambda) fractions (P < 0.001) were lower in T. gondii-seropositive than in seronegative blood donors. This significant alteration in redox status between seropositive and seronegative donors suggested a degradation of their antioxidant enzymes caused by OS induced by increased free radicals attributable to toxoplasmosis infection. T. gondii infection also had a prominent influence on the association between OS biomarkers and immune-suppression status in seropositive donors.