Background Toxoplasma gondii infection is an important cause of ocular disease. Although parasite-mediated host cell lysis is probably the principal cause of tissue destruction in immunodeficiency states, hypersensitivity and inflammatory responses may underlie severe disease in otherwise immunocompetent individuals. The purpose of the current investigation was to study the cytokine profiles in serum from patients with ocular toxoplasmosis and to compare them with those obtained from healthy control subjects.

Methods Using a multiplex assay, we determined the serum concentration of granulocyte colony-stimulating factor (GCSF), interferon γ (IFNγ), interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, chemokine (C-C motif) ligand 2 (CCL2) and tumour necrosis factor α (TNFα) in patients with inactive ocular toxoplasmosis (n=48), active ocular toxoplasmosis (n=21), and an age-matched and sex-matched healthy control group (n=25). In a subgroup of 17 patients with active disease, a second serum sample was obtained when the disease was inactive. Cytokine profiles were correlated with disease activity, severity and visual outcome.

Results Levels of CCL2 were significantly reduced in patients with active ocular toxoplasmosis compared to the control group (564±42 pg/mL vs 455±35 pg/mL, p<0.05). Moreover, CCL2 levels were significantly lower during active ocular toxoplasmosis compared to inactive disease (569±32 pg/mL vs 433±32 pg/mL, p<0.01). GCSF and TNFα were elevated in patients with toxoplasmosis with poor visual outcome. No significant correlations were found with specific cytokine profiles and disease severity.

Conclusions Decreased serum levels of CCL2 may be associated with active ocular toxoplasmosis and could therefore serve as a marker of disease activity.