Peripheral immune response in human toxoplasmosis depends on clinical condition but not on the antigen

Abstract

Purpose: The peripheral immune response is incompletely known in human toxoplasmosis. We aimed to study this response and the cytokine production regarding P30 and ROP 18 protein-derived Toxoplasma peptides.

Methods: The specific lymphocyte proliferative response and cytokine profile production regarding Toxoplasma P30 (2017 from virulent and non-virulent strain) and ROP18 protein-derived peptides (from clonal lineages I, II and III) were determined in 19 patients having ocular toxoplasmosis, five suffering chronic asymptomatic infection, 9 with congenital toxoplasmosis and 8 Toxoplasma negative people. A Beckman-Coulter FC500n flow cytometer was used for determining antigen-specific T-cells (CD3+CD4+ or CD3+CD8+ cells) in peripheral blood culture. IFNg and IL10 levels were determined in culture supernatants.

Results: Specific CD4+ and CD8+ T-cell response to total antigen and P30- and ROP18-derived peptides was observed in infected people. Ocular toxoplasmosis patients had a preferential Th2 response after antigenic stimulation. Non-virulent peptide 2017 was able to shift response towards Th1 in congenitally-infected children and virulent peptide 2017 induced a Th2 response in chronically-infected, asymptomatic people.

Conclusions: An immune response in human toxoplasmosis after ex vivo antigenic stimulation was Th1- or Th2-skewed, depending on a patient’s clinical condition. Colombian ocular toxoplasmosis patients’ immune response was Th2-skewed, regardless of the nature of antigen stimulus.

Keywords: 734 toxoplasmosis • 553 immune tolerance/privilege • 451 chorioretinitis