Human peripheral blood mononuclear cells as an ex vivo model to study the host parasite interaction in Toxoplasma gondii.

Toxoplasma gondii is a parasite that can invade any cell in the human body. Here, we implemented and described an ex vivo model with human peripheral blood mononuclear cells (PBMCs) without using culture supplements/antibiotics and without cryopreserved cells (EXMOWS) to study the interactions between T. gondii and human cells. To establish the EXMOWS, three independent tests were carried out. Firstly, blood samples from 5 individuals were included to assess the viability and adherence of PBMCs in plate culture. In a second trial, blood samples from three seropositive and two seronegative individuals for T. gondii were used to evaluate human PBMCs cells: parasites, multiplicity of infection (MOI) 1:1, 1:3 and 1:5 at different times post infection (1 h, 6 h and 24 h). The possible immunomodulatory effect of the infection for this EXMOWS were evaluated in a third trial where HFF cells were infected with T. gondii and co-cultured with PBMCs obtained from anti-Toxoplasma IgG positive and IgG negative individuals. One hour was enough time for T. gondii infection of human PBMCs and 2 h was the minimum incubation time to guarantee adherence before carrying out any infection assay. A minimum of 1:3 MOI was necessary to guarantee efficient infection in human PBMCs with T. gondii RH-GFP. All protocols, including PBMCs isolation and stimulation, should be conducted the same day. This EXMOWS can be adapted to study the early stages of interaction with other microorganisms of human interest, without need of using cryopreservation and supplements/antibiotics.