Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 20 2 2025 06 08 307 315 Salah Alnisani 1. Laboratory of Molecular and Cellular Screening Processes, Center of Biotechnology of Sfax, Sfax, Tunisia 2. Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia Ahmed Rebai Laboratory of Molecular and Cellular Screening Processes, Center of Biotechnology of Sfax, Sfax, Tunisia 2024 12 18 2025 03 01 Background: We aimed to investigate the presence of thyroid peroxidase antibodies (anti-TPO) in women with spontaneous abortion, both with and without toxoplasmosis. This was achieved by evaluating and comparing the serum levels of interleukins IL-4, IL-6, IL-10, IL-17, and TNF-α in women who experienced abortion due to toxoplasmosis, categorized by positive and negative anti-TPO status, with those who were toxoplasmosis-negative and also negative for anti-TPO. Methods: We evaluated the serological presence of IgG and IgM antibodies to Toxoplasma using an ELISA method, in Samarra City, Salah al-Din Governorate, Iraq in 2021-2022. A sample of 153 women with spontaneous abortion were enrolled. We also measured the serum levels of interleukins IL-4, IL-6, IL-10, IL-17, TNF-α, and anti-TPO using the same technique. Results: Overall, 103 were Toxoplasma-positive. Of these, 14 had positive anti-TPO results (13.5%), compared to only 3 positive cases among the 50 matched controls who were Toxoplasma-negative (6.0%). The difference between Toxoplasma-positive and Toxoplasma-negative women regarding anti-TPO status was statistically significant for interleukins IL-4 (P=0.010), IL-6 (P=0.017), and IL-10 (P=0.003), but not for IL-17 or TNF-α. Additionally, the statistical analysis revealed a highly significant difference in the average concentrations of interleukins IL-4 (P=0.013) and IL-10 (P<0.001) between the Toxoplasma-positive/anti-TPO-positive group and the Toxoplasma-negative/anti-TPO-negative group of aborted women. Conclusion: Elevated concentrations of IL-4, IL-10, and IL-6 have been associated with women undergoing recurrent miscarriages and negative anti-TPO results. The complex interaction between pro-inflammatory and anti-inflammatory cytokines is essential for immunological balance and pregnancy outcomes in a condition of toxoplasmosis. An increase in IL-4 and IL-10 levels in anti-TPO-positive individuals may lead to an imbalance in immune response, facilitating the development of autoimmune thyroid disease. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/4488 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/4488/1435