This work analyzed exhaustion markers in CD8 T-cell subpopulations in 21 samples of peripheral blood mononuclear cells (PBMCs) from individuals with ocular toxoplasmosis (n = 9), chronic asymptomatic toxoplasmosis (n = 7), and non-infected people (n = 5) by using RT-qPCR and flow cytometry techniques. The study found that gene expression of PD-1 and CD244, but not LAG-3, was higher in individuals with ocular toxoplasmosis versus individuals with asymptomatic infection or uninfected. Expression of PD1 in CD8 central memory (CM) cells was higher in nine individuals with toxoplasmosis versus five uninfected individuals (p =.003). After ex vivo stimulation, an inverse correlation was found between the exhaustion markers and quantitative clinical characteristics (lesion size, recurrence index, and number of lesions). A total exhaustion phenotype was found in 55.5percent-flag-change (5/9) of individuals with ocular toxoplasmosis. Our results suggest that the CD8 exhaustion phenotype is involved in the pathogenesis of ocular toxoplasmosis.
