The effect of Toxoplasma gondii on some critical immunological markers in rheumatoid arthritis Iraqi patients

Toxoplasmosis caused by Toxoplasma gondii (T. gondii) affects one-third of the world human population. One of immune evasion strategy in the host-parasite interplay is HLA-G level alteration. HLA-G known as a special proteins (non-classical HLA class I) molecules which can suppress the immune system and its capability of modulating natural killer cell (NK) function such as cytotoxicity and cytokine production through NK cell receptors, specially KIR2DL4 receptor. KIR2DL4 a member of KIR family, featured with both inhibitory and activating functional structure, has been described as the specific receptor for HLA-G. So, this study aimed to investigate the alteration in sHLA-G and its receptor levels could be impressed by present of Toxoplasma and rheumatoid as well as the seroprevalence of Toxoplasma gondii antibodies in Iraqi patients with rheumatoid arthritis (RA) was investigated. The prevalence of anti-T. gondii IgG was significantly higher in arthritic patients (50%) compared with (41.6%) in healthy controls. No positive anti-T. gondii IgM was detected. The results showed that treated RA patients without Toxoplasma had the highest significant (P≤0.01) increase level of sHLA-G in comparison to RA untreated patients, also treated RA patients without Toxoplasma showed high significant increase (P≤0.01) of sHLA-G in comparison to untreated RA patients, while the level of sHLA-G in patients with toxoplasmosis only significantly (P≤0.01) increased in comparison to control, whilst that treated RA patients without Toxoplasma had the highest significant (P≤0.01) increase level of KIR2DL4 in comparison to RA untreated patients, while, treated RA patients with Toxoplasma showed high significant increase (P≤0.01) of KIR2DL4 in comparison to RA untreated patient. Also, the results of the level of KIR2SL4 in patients with toxoplasmosis only showed significantly (P≤0.01) decreased in comparison to control. The present study describes the change in HLA-G and KIR2DL4 levels in present of Toxoplasma and RA.